Co-reporter:Hong Ping Xiang, Min Zhi Rong, Ming Qiu Zhang
Polymer 2017 Volume 108() pp:339-347
Publication Date(Web):13 January 2017
DOI:10.1016/j.polymer.2016.12.006
•Crosslinked polydimethylsiloxane exhibits sunlight induced dynamicity.•Catalyst-free disulfide metathesis in silicone elastomer is activated by sunlight.•Silicone elastomer can be repeatedly self-healed and recycled under sunshine.A crosslinked silicone elastomer is prepared by utilizing polydimethylsiloxane as the host material and disulfide bond-containing silane as the crosslinking agent. By taking advantage of the sunlight activated metathesis of the included disulfide bonds, the crosslinked silicone elastomer can be self-healed and recycled for multiple times without any catalyst under sunshine. A series of verification experiments are carried out to reveal the underlying mechanism and the dynamicity of the silicone. Because the key raw materials are commercially available and the manufacturing follows common industrial procedures, the outcomes of this proof-of-concept study may be easily applied in practice. The simple and eco-friendly method would help to increase reliability and durability of silicone products and minimize wasting of resources.
Co-reporter:Yeru Liang;Yingbo Ruan;Junlong Huang;Bo Peng;Chen-Yang Liu
Science China Chemistry 2017 Volume 60( Issue 8) pp:1084-1089
Publication Date(Web):05 July 2017
DOI:10.1007/s11426-017-9074-8
Design and fabrication of the micro/nanostructures of the network units is a critical issue for porous nanonetwork structured materials. Significant progress has been attained in construction of the network units with zero-dimensional spherical shapes. However, owing to the limitations of synthetic methods, construction of porous building blocks in one dimension featuring high aspect ratios for porous nanonetwork structured polymer (PNSP) remains largely unexplored. Here we present the successful design and preparation of PNSP with a novel type of one-dimensional network unit, i.e., microporous heterogeneous nanowire. Well-defined core-shell polymer nanoobjects prepared from a gelable block copolymer, poly(3-(triethoxysilyl)propyl methacrylate)-block-polystyrene are employed as building blocks, and facilely transformed into PNSP via hypercrosslinking of polystyrene shell. The as-prepared PNSP exhibits unique three-dimensional hierarchical nanonetwork morphologies with large surface area. These findings could provide a new avenue for fabrication of unique well-defined PNSP, and thus generate valuable breakthroughs in many applications.
Co-reporter:Nan Nan Xia, Xiao Min Xiong, Junhu Wang, Min Zhi Rong and Ming Qiu Zhang
Chemical Science 2016 vol. 7(Issue 4) pp:2736-2742
Publication Date(Web):12 Jan 2016
DOI:10.1039/C5SC03483C
In this work, water triggered dynamic catechol–Fe3+ coordinate bonds are revealed and studied at atomic, molecular and macroscopic levels using Mössbauer spectroscopy, rheological analysis, etc. DOPA–iron complexation is found to be dynamic in the presence of water, and this dynamic manner is immobilized after removing water. Accordingly, a water saturated lipophilic polymer containing catechol–Fe3+ crosslinks, rather than the dry version, exhibits dynamic coordination–dissociation behavior. In addition, a migration of iron proves to be enabled in the catechol–Fe3+ crosslinked polymer immersed in seawater. Rearrangement of the dynamic catechol–Fe3+ coordinate bonds among different molecules is thus favored. Based on these results, we develop a bulk lipophilic polymer solid capable of repeated autonomic recovery of strength in seawater without manual intervention. When the polymer is damaged in seawater, reshuffling of the mobile hyperbranched polymer networks across the crack interface, owing to the dynamic catechol–Fe3+ crosslinkages activated by the alkaline circumstances, rebinds the damaged site. By taking advantage of the same mechanism, the polymer can be remolded with the help of seawater and this recycled polymer is still self-healable in seawater. Unlike in the case of conventional polymers where water would shield macromolecules from interacting, here, seawater is a necessary environmental assistant for the material interaction to take effect. The outcomes are beneficial for deepening the understanding of coordinate bonds, and the development of robust underwater self-healing lipophilic polymers.
Co-reporter:Wei Min Xu, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2016 vol. 4(Issue 27) pp:10683-10690
Publication Date(Web):13 Jun 2016
DOI:10.1039/C6TA02662A
For realizing sunlight stimulated self-healing, a crosslinked polyurethane carrying disulfide in the main chain is synthesized. Its macromolecular composition and architecture are optimized so that the included disulfide bonds can take part in the exchange reaction simply under illumination of the low concentration UV component of sunlight. Accordingly, the damaged polymer is allowed to be repeatedly healed in the sun in terms of strength restoration as a result of photo-triggered reversible exchange of disulfide bonds. Meanwhile, the elaborately introduced hydrogen bonding helps to quickly close cracks, favoring intimate contacts of the cracked surface and subsequent interaction of dangling chains across the interface, and eventually raising the effectiveness of the photo-reaction of the disulfide bonds in the solid phase. In addition, network rearrangement due to disulfide exchange enables multiple recycling and reshaping of the polymer under sunshine. The present proof-of-concept work would be hopefully developed into a cost-effective and environmentally friendly technology of design, fabrication and application of smart photo-sensitive polymers with high mechanical strength.
Co-reporter:Yangfan Zhang, Yunhong Tan, Kang Yang, Zexiong Wu, Zishou Zhang, Mingqiu Zhang and Kancheng Mai
Journal of Materials Chemistry A 2016 vol. 4(Issue 26) pp:10091-10097
Publication Date(Web):29 Apr 2016
DOI:10.1039/C6TA02161A
Molecular chain bonding is, for the first time, developed to synthesize a nanoporous, flexible and conductive polymer composite by converting a single polymer phase matrix to two phases of interpenetrating polymer networks. Significantly, the porous polymer composite not only presents ultra-high mechanical properties, durability and conductive stability, but also enhances the capacitance by 7-fold.
Co-reporter:Hong Ping Xiang, Min Zhi Rong, and Ming Qiu Zhang
ACS Sustainable Chemistry & Engineering 2016 Volume 4(Issue 5) pp:2715
Publication Date(Web):March 31, 2016
DOI:10.1021/acssuschemeng.6b00224
To develop a new technology for sustainable application of sulfur cross-linked rubbers, a novel latent catalyst, organic complex copper(II) methacrylate (MA-Cu), is explored to trigger disulfide metathesis at elevated temperature. When it is incorporated into vulcanized chloroprene rubber fabricated following industrial recipe, reshuffling of inherent sulfur cross-links is enabled typically at 120 °C, while microstructure of the material remains unchanged at lower temperature (typically lower than 100 °C). Such a latent character of MA-Cu is believed to ensure operation stability of the rubber under ambient conditions, and its organic nature helps to improve dispersion homogeneity. By taking advantage of the activated cross-linked networks, the sulfur bonds can be reversibly exchanged inside the vulcanized chloroprene rubber as well as across the surfaces at 120 °C. As a result, the rubber is coupled with the capabilities of repeated reshaping, self-healing, and recycling without need of changing its macromolecular structure and manufacturing parameters. These outcomes might lead to the development of energy saving and environmentally friendly all solid-state processing of cross-linked polymers toward multitask cyclic utilization.Keywords: Disulfide metathesis; Reclaiming; Reshaping; Self-healing; Sulfur cross-linked network; Vulcanized rubber
Co-reporter:Jia Jia Huang, Min Zhi Rong and Ming Qiu Zhang
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 6) pp:4800-4806
Publication Date(Web):14 Jan 2016
DOI:10.1039/C5CP06582H
A simple, effective and green bottom-up method for the synthesis of highly fluorescent N doped graphene oxide quantum dots (GOQDs) and polymer-like quantum dots (PQDs) was developed on the basis of rapid one-step microwave assisted pyrolysis of citric acid (CA) and diethylenetriamine (DETA) in different reaction solvents. Both one-photon-induced and two-photon-induced photoluminescence (PL) properties of the resultant GOQDs and PQDs were characterized and analyzed. The one-photon-induced PL quantum yields (QY) of GOQDs and PQDs reached 39.8 and 74.0%, respectively, which are high enough to exhibit strong photoluminescence (PL) emission even under daylight excitation. The origin of the PL behavior and PL quenching mechanism was explored in terms of the interaction between the functional groups on the surfaces of GOQDs or PQDs and Hg2+. Furthermore, due to the excellent selectivity and sensitivity of the GOQDs and PQDs to Hg2+, the quantum dots might be used for quantitative detection of Hg2+ in aqueous solution.
Co-reporter:Yong Zhu, Xiao Ji Ye, Min Zhi Rong, Ming Qiu Zhang
Composites Science and Technology 2016 Volume 135() pp:146-152
Publication Date(Web):27 October 2016
DOI:10.1016/j.compscitech.2016.09.020
To improve flowability of the healing agent released from micropipelines without manual intervention, this work prepared a proof-of-concept self-healing glass fiber/epoxy composite, in which plastic (polypropylene (PP)) tubes were embedded and used as containers of epoxy/mercaptan healing agent and foaming agent. Decomposition of the foaming agent at 70 °C created inflated gas in the sealed PP tubes in advance, which increased the internal pressure. Upon damage of the composite, the pressurized healing fluid burst out covering larger cracked plane and enhanced mixing of the liberated epoxy monomer and hardener. As a result, higher healing efficiency was observed as compared to the case without pressurization. The factors that influence healing performance of the system (e.g., tube spacing, content of the foaming agent, foaming time, etc.) were discussed in detail. The proposed approach is believed to have adequate expansibility and can be applied in other self-healing composites with micropipelines.
Co-reporter:Ze Ping Zhang, Yan Lu, Min Zhi Rong and Ming Qiu Zhang
RSC Advances 2016 vol. 6(Issue 8) pp:6350-6357
Publication Date(Web):11 Jan 2016
DOI:10.1039/C5RA22275C
To improve the room temperature application stability of a dynamically reversible self-healing system based on alkoxyamine moieties, and to provide the polymer with oxygen insensitive self-healability, a crosslinked methyl methacrylate polymer with embedded alkoxyamine moieties that contain amido groups is prepared. Owing to synchronous fission/radical recombination of C–ON bonds, cracks in the polymer can be repeatedly healed without an additional catalyst, and the polymer itself can be remolded in the solid state or even decomposed by nitroxides in a controlled manner. The homolysis temperature of the dynamic reversible alkoxyamine derivative, which is closely related to crack healing and the reprocessing temperature of the polymer, is adjusted to be higher than room temperature by means of the appropriate electron-absorbing feature of amido groups. Meanwhile, the healing chemistry is coupled with air resistance. Besides, thiol–ene click chemistry is used to synthesize the target polymer. The possible side reaction that reduces the concentration of reversible bonds during polymerization is minimized accordingly.
Co-reporter:Gábor Szebényi, Tibor Czigány, Brúnó Vermes, Xiao Ji Ye, Min Zhi Rong, Ming Qiu Zhang
Polymer Testing 2016 Volume 54() pp:134-138
Publication Date(Web):September 2016
DOI:10.1016/j.polymertesting.2016.07.005
The failure process of self-healing microcapsule filled epoxy composites was investigated with Acoustic Emission (AE) measurement during tapered double cantilever beam (TDCB) tests. Unfilled, epoxy microcapsule filled and self-healing microcapsule (dual-microcapsules consisting of epoxy capsules and trifluoromethanesulfonic acid (TfOH) capsules) filled epoxy matrix specimens were compared. It was found that, with acoustic emission measurements, reliable data can be retrieved about the nature and progress of crack propagation and failure. Comparing the unfilled and the microcapsule filled specimens, considerably more AE hits were detected in the latter case due to the cracking of capsules and capsule-matrix debonding, which was confirmed by scanning electron microscopy investigations. Also, key differences were observed in the shape of the sum of AE hits curves and amplitude ranges of detected AE hits. Uniform distribution of the healing agent was demonstrated by energy-dispersive X-ray spectroscopy.
Co-reporter:Habibah Ghazali, Lin Ye, Ming Q. Zhang
Composites Part A: Applied Science and Manufacturing 2016 Volume 82() pp:226-234
Publication Date(Web):March 2016
DOI:10.1016/j.compositesa.2015.12.012
We present an experimental study of the self-healing ability of carbon fibre/epoxy (CF/EP) composite laminates with microencapsulated epoxy and its hardener (mercaptan) as a healing agent. Epoxy- and hardener-loaded microcapsules (average size large: 123 μm; small: 65 μm) were prepared by in situ polymerisation in an oil-in-water emulsion and were dry-dispersed at the ratio 1:1 on the surface of unidirectional carbon fabric layer. The CF/EP laminates were fabricated using a vacuum-assisted resin infusion (VARI) process. Width-tapered double cantilever beam (WTDCB) specimens were used to measure mode-I interlaminar fracture toughness of the CF/EP composites with a pre-crack in the centre plane where the microcapsules were placed. Incorporation of the dual-component healant stored in the fragile microcapsules provided the laminates with healing capability on delamination damage by recovering as much as 80% of its fracture toughness. It was also observed that the recovery of fracture toughness was directly correlated with the amount of healant covering the fracture plane, with the highest healing efficiency obtained for the laminate with large capsules.
Co-reporter:Dr. Pu Xie; Min Zhi Rong; Ming Qiu Zhang
Angewandte Chemie International Edition 2016 Volume 55( Issue 5) pp:1805-1809
Publication Date(Web):
DOI:10.1002/anie.201510686
Abstract
The present communication reports a concept battery made by direct contact of magnesium foil with ultralight polyaniline (PANI) foam in the absence of additional electrolyte. Electrical current is allowed to be steadily released from the junction with a specific energy of 646 mWh g−1 and specific capacity of 1247 mAh g−1. Additionally, the battery offers an environmentally friendly route of hydrogen production along with discharging. Mechanistic studies indicated that the ubiquitous galvanic corrosion combined with decomposition of adsorbed trace water in the semi-conducting polymer foam enabled the generation of electricity, which overturns the traditional view. The higher moisture level is conducive to the discharge. This work is believed to open up new possibilities for the design of electrochemical batteries.
Co-reporter:Dr. Pu Xie; Min Zhi Rong; Ming Qiu Zhang
Angewandte Chemie 2016 Volume 128( Issue 5) pp:1837-1841
Publication Date(Web):
DOI:10.1002/ange.201510686
Abstract
The present communication reports a concept battery made by direct contact of magnesium foil with ultralight polyaniline (PANI) foam in the absence of additional electrolyte. Electrical current is allowed to be steadily released from the junction with a specific energy of 646 mWh g−1 and specific capacity of 1247 mAh g−1. Additionally, the battery offers an environmentally friendly route of hydrogen production along with discharging. Mechanistic studies indicated that the ubiquitous galvanic corrosion combined with decomposition of adsorbed trace water in the semi-conducting polymer foam enabled the generation of electricity, which overturns the traditional view. The higher moisture level is conducive to the discharge. This work is believed to open up new possibilities for the design of electrochemical batteries.
Co-reporter:H. P. Xiang, H. J. Qian, Z. Y. Lu, M. Z. Rong and M. Q. Zhang
Green Chemistry 2015 vol. 17(Issue 8) pp:4315-4325
Publication Date(Web):02 Jun 2015
DOI:10.1039/C5GC00754B
CuCl2 has been shown to effectively catalyze reshuffling of the inherent sulfur crosslinked networks of vulcanized rubber. Once activated, CuCl2-based complex catalysis enables disulfide metathesis through circulated crossover reactions among disulfide and polysulfide bonds without forming radicals and ionic intermediates. By taking advantage of this mechanism, the model material of this study, vulcanized polybutadiene rubber, acquires thermal remendability as characterized by repeated restoration of mechanical properties. Moreover, it can be reprocessed like thermoplastics. The compositions and fabrication of the model material simulate those of industrial vulcanized rubber, so as to facilitate formulation optimization under the circumstances close to the actual situation for possible future practical applications. It is hoped that the results of the present preliminary exploration would provide the basis for extending the service life and developing new recycling techniques of vulcanized rubber, which is produced, used and scrapped in large quantities every day.
Co-reporter:Dong Yu Zhu, Jian Wei Guo, Guang Sheng Cao, Wen Lian Qiu, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2015 vol. 3(Issue 5) pp:1858-1862
Publication Date(Web):11 Dec 2014
DOI:10.1039/C4TA06381C
Commercially available polystyrene is coupled with self-healability by exploiting a novel healing chemistry of redox cationic polymerization. In this system, iodonium bis(4-methylphenyl) hexafluorophosphate (IBH)/glycidyl methacrylate (GMA) loaded microcapsules and NaBH4 particles are embedded in the matrix through compression molding. The healant is oxygen insensitive and heat resistant so that it meets the requirement of remendable thermoplastics.
Co-reporter:Wei Hong, Yu Zhang, Lin Gan, Xudong Chen and Mingqiu Zhang
Journal of Materials Chemistry A 2015 vol. 3(Issue 24) pp:6185-6191
Publication Date(Web):14 May 2015
DOI:10.1039/C5TC00464K
Ordered arrays of Ag-capped colloidal crystals were fabricated and modified with conjugated polymers to evaluate the excitation and emission fluorescence enhancement due to localized surface plasmon resonance (LSPR). The maximum enhancement accrued on the maximum overlap between the excitation wavelength and LSPRs of the substrates. The observed fluorescence enhancement and lifetime measurement showed that the large enhancement came from a combination of greatly enhanced excitation and an increased radiative decay rate, leading to an associated enhancement of the quantum efficiency. Thus, such Ag nanostructured arrays fabricated by colloidal lithograph show great potential for biosensing and photovoltaic applications, and the excitation wavelength–LSPR-based fluorescence enhancement proves useful for understanding and optimizing metal-enhanced fluorescence.
Co-reporter:Zhou Qiao Lei, Pu Xie, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2015 vol. 3(Issue 39) pp:19662-19668
Publication Date(Web):03 Sep 2015
DOI:10.1039/C5TA05788D
The present work reveals that catalyst-free dynamic reversible exchange of aromatic Schiff base bonds is enabled at room temperature. Attachment of aryl groups to both nitrogen and carbon atoms of carbon–nitrogen double bonds is a critical structural factor that contributes to the dynamic characteristics and complete reaction between aromatic aldehyde and aromatic amine. The exchange mechanism is studied by model compounds, and free radical intermediates are found to be involved in the non-equilibrium stage of the exchange reaction. By taking advantage of the dynamic equilibrium of aromatic Schiff base bonds, infusible and insoluble crosslinked polyacrylate is self-healed and reprocessed through rearrangement of macromolecular networks. The reprocessed polymer is still self-healable. Either the self-healing or reprocessing is completed in air without heating. Considering that Schiff base polymers have shown diverse properties and stimulus–response behaviors, activation of the dynamic exchange of the inherent Schiff base bonds would result in a series of novel functionalities. More interestingly, traditional crosslinked polymers might thus be provided with a facile way of being smarter.
Co-reporter:Yu Zhang, Wei Hong, Minfeng Li, Zhe Zhao, Lin Gan, Jiemei Ou, Xudong Chen, Mingqiu Zhang
Journal of Physics and Chemistry of Solids 2015 Volume 85() pp:75-80
Publication Date(Web):October 2015
DOI:10.1016/j.jpcs.2015.05.003
•We study the metal surface plasmon-enhanced emission of conjugated polymer (poly[2,5-bis(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene], BDMO-PPV) in the process that silver metal substrates changed from isolated nano-particles to continuous metal film•The photoluminescence (PL) enhancement was mainly raised from coupling of BDMO-PPV excitons with localized surface plasmon (LSP) of Ag nano-particles when the thickness of deposited Ag film was smaller than 15 nm.•However, surface plasmon polaritons (SPPs) dominated the PL enhancement when the thickness of deposied Ag film reached 20 nm or thicker.Herein we report a symmetric study of metal surface plasmon-enhanced emission of conjugated polymer (poly[2,5-bis(3′,7′-dimethyloctyloxy)-1,4-phenylenevinylene], BDMO-PPV) in the process that silver metal substrates changed from isolated nano-particles to continuous metal film. It was found that photoluminescence (PL) enhancement was mainly raised from coupling of BDMO-PPV excitons with localized surface plasmon (LSP) of Ag nano-particles when the thickness of deposited Ag film was smaller than 15 nm. However, surface plasmon polaritons (SPPs) dominated the PL enhancement when the thickness of deposited Ag film reached 20 nm or thicker. Temperature dependent PL of BDMO-PPV on the silver substrates were also investigated in the range of 10–300 K. Bose–Einstein statistical factors were calculated to reveal the mechanistic aspects of the observed temperature dependent fluorescence enhancement on Ag nano-films with variable thickness.
Co-reporter:Dong Yu Zhu, Guang Sheng Cao, Wen Lian Qiu, Min Zhi Rong, Ming Qiu Zhang
Polymer 2015 Volume 69() pp:1-9
Publication Date(Web):9 July 2015
DOI:10.1016/j.polymer.2015.05.052
•PVC acquires room temperature self-healability based on nucleophilic thiol-click chemistry.•The microencapsulated healant is heat resistant and oxygen insensitive.•Both functional groups of GMA effectively participate in the healing reaction.Polyvinyl chloride (PVC), a typical commodity thermoplastic polymer, is enabled for self-healing using nucleophilic thiol-click chemistry. A healing agent consisting of bifunctional monomer glycidyl methacrylate (GMA), polythiol pentaerythritol tetrakis (3-mercaptopropionate) (PETMP) and basic catalyst 2,4,6-tris(dimethylaminomethyl) phenol (DMP-30) shows good wetting of the PVC matrix, fast reaction kinetics, a high resistance to thermal processing, and tolerance to oxygen. The PVC composite containing microencapsulated healant was fabricated by hot compression molding and exhibited autonomic self-healability characterized by the recovery of mechanical strength within 2–3 h at room temperature in air. Both the CC and epoxide group of GMA participate in the reaction with polythiol, but the thiol-ene “click” reaction proceeds faster than the thiol-epoxy reaction. The outcomes of the present study contribute to developing new healing agents and expand the family of self-healing thermoplastics.
Co-reporter:J. Lee, D. Bhattacharyya, M.Q. Zhang, Y.C. Yuan
Composites Part B: Engineering 2015 Volume 78() pp:515-519
Publication Date(Web):1 September 2015
DOI:10.1016/j.compositesb.2015.04.014
Inspired by biological systems in which damage triggers an autonomic healing response, a polymer composite material that can heal itself when cracked has been developed. In this work, compression and tensile properties of a self-healed fibre reinforced epoxy composites were investigated. Microencapsulated epoxy and mercaptan healing agents were incorporated into a glass fibre reinforced epoxy matrix to produce a polymer composite capable of self-healing. The self-repair microcapsules in the epoxy resin would break as a result of microcrack expansion in the matrix, and letting out the strong repair agent to recover the mechanical strength with a relative healing efficiency of up to 140% which is a ratio of healed property value to initial property value or healing efficiency up to 119% if using the healed strength with the damaged strength.
Co-reporter:Zhou Qiao Lei, Hong Ping Xiang, Yong Jian Yuan, Min Zhi Rong, and Ming Qiu Zhang
Chemistry of Materials 2014 Volume 26(Issue 6) pp:2038
Publication Date(Web):February 20, 2014
DOI:10.1021/cm4040616
Tri-n-butylphosphine (TBP) has been shown to effectively catalyze an air-insensitive disulfide metathesis reaction under alkaline conditions at room temperature. A cross-linked polysulfide containing the phosphine exhibited repeated autonomous self-healing resulting in restoration of tensile strength as a result of the dynamic exchange of disulfide bonds. Interestingly, the cross-linked polysulfide can also be reshaped and reprocessed at room temperature via the TBP-mediated reshuffling of the macromolecular networks. The mechanical properties and self-healing ability of polymeric specimens made from chopped samples remain surprisingly constant. In sharp contrast, control specimens without the phosphine catalyst or S–S bonds are neither self-healable nor reprocessable.
Co-reporter:Pu Xie, Hong Liu, Shou Ji Qiu, Min Zhi Rong, Ming Qiu Zhang, Zhong Yuan Lu and Su Ping Wu
Green Chemistry 2014 vol. 16(Issue 3) pp:1225-1235
Publication Date(Web):15 Oct 2013
DOI:10.1039/C3GC41506F
To produce soybean oil based foam plastics in terms of the supercritical carbon dioxide foaming technique, the B-stage gel formed by the radical copolymerization of acrylated epoxidized soybean oil (AESO) and styrene (St) was prepared and studied. Accordingly, a dual initiator system consisting of cyclohexanone peroxide (CP) and di-tert-butyl peroxide (DTBP) catalyzed by cobalt octoate (CoOct) was introduced, which provided the gel with (i) good permeability and sufficient thermal stability for saturation in the supercritical carbon dioxide and (ii) polymerizability for freezing the depressurization induced cells during post cure at higher temperatures. The relationships among the reaction processes, structural evolvement and properties variation were characterized and analyzed. Additionally, the experimental results were verified by a numerical simulation. It is hoped that the outcome of this work would not only deepen the understanding of the intermediate status of thermosets, but also help to determine the optimal conditions for fabricating thermosetting foams by supercritical carbon dioxide foaming.
Co-reporter:Chan'e Yuan, Ming Qiu Zhang and Min Zhi Rong
Journal of Materials Chemistry A 2014 vol. 2(Issue 18) pp:6558-6566
Publication Date(Web):06 Feb 2014
DOI:10.1039/C4TA00130C
To provide epoxy with intrinsic self-healing ability, a new alkoxyamine based diol was synthesized and incorporated into an epoxy monomer, which was then compounded with traditional bisphenol A diglycidyl ether and cured by diethylenetriamine. Taking advantage of dynamic equilibrium of thermally reversible reaction of C–ON bond in alkoxyamine, cracked portions of the functionalized epoxy material can be repeatedly reconnected at certain temperature, as characterized by restoration of impact strength and visual inspection as well. Unlike the two-step self-healing approach based on reversible Diels–Alder reaction, the present one only needed one step. Owing to the steric hindrance of tertiary butyl group in the diol, onset of scission of C–ON bonds and radical recombination (i.e., healing reaction) occurred at lower temperature. Additionally, reversibility of the alkoxyamine derivatives was improved with incorporation of Si–O bonds into the epoxy chains. The present work carefully studied thermal reversibility, thermal stability, dynamic mechanical behavior and healing performance of the epoxy in relation to molecular structure. The outcomes might help to optimize the material and guide future design of novel epoxy monomers.
Co-reporter:Xiao Ji Ye, Ji-Long Zhang, Yong Zhu, Min Zhi Rong, Ming Qiu Zhang, Yi Xi Song, and Hong-Xing Zhang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 5) pp:3661
Publication Date(Web):February 12, 2014
DOI:10.1021/am405989b
Self-healing materials should take effect immediately following crack generation in principle, but the speed of autonomic recovery of mechanical properties through either extrinsic or intrinsic healing strategy reported so far is not that fast. Mostly, a couple of hours are taken for reaching steady state or maximum healing. To accelerate the healing process, the authors of this work make use of antimony pentafluoride as instant hardener of epoxy and successfully encapsulate the highly active antimony pentafluoride–ethanol complex in terms of hollow silica spheres. Accordingly, self-healing agent based on microencapsulated antimony pentafluoride–ethanol complex and epoxy monomer is developed. Epoxy material with the embedded healant capsules can thus be healed within a few seconds, as demonstrated by impact and fatigue tests. It is believed that the outcome presented here might help to move the self-healing technique closer to practical application, especially when the engineering significance of epoxy material is concerned.Keywords: epoxy; fast cure; healing speed; Lewis acid; self-healing;
Co-reporter:Yunyun Huang, Wensheng Lin, Kan Chen, Wenkai Zhang, Xudong Chen and Ming Qiu Zhang
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 23) pp:11584-11589
Publication Date(Web):14 Mar 2014
DOI:10.1039/C4CP00773E
A water-processable blue fluorescent silver nanoparticle@graphene–polymer composite (Ag@G–pNIPAM) consisting of graphene coated with a thermally responsive poly-(N-isopropylacrylamide) (pNIPAM) shell is prepared. The pNIPAM shell swells or collapses as a function of temperature, serving as a means to trap silver nanoparticles in solution and get them sufficiently close to the graphene core to provide fluorescence enhancement based on the local surface plasmon resonance (LSPR) effect. The unique thermoresponsive properties and high enhancement ratio of the material should find application in solution fluorescence enhancers and a variety of biomedical applications, such as cellular uptake, sensing and imaging.
Co-reporter:Min Zhu;Min Zhi Rong;Ming Qiu Zhang
Polymer International 2014 Volume 63( Issue 10) pp:1741-1749
Publication Date(Web):
DOI:10.1002/pi.4723
Self-healing of polymers and polymer composites initially represented a process capable of autonomic restoration of mechanical strength upon cracking of the materials, but it is moving into the area of restoration of functionality. This mini-review is focused on recent efforts to develop functional polymers with built-in stimuli-responsive ability to heal for recovery of their specific physical or chemical properties. Molecular design and synthesis, compounding and assembly of organic and inorganic species, inherent reversibility, etc., are summarized. It is hoped that much more interest will be aroused in this emerging and promising frontier topic. © 2014 Society of Chemical Industry
Co-reporter:Xiao-Ji Ye, Zhuo-Xi Ma, Yi-Xi Song, Jia-Jia Huang, Min-Zhi Rong, Ming-Qiu Zhang
Chinese Chemical Letters 2014 Volume 25(Issue 12) pp:1565-1568
Publication Date(Web):December 2014
DOI:10.1016/j.cclet.2014.07.002
To accelerate self-healing speed of epoxy materials, epoxy-SbF5 cure was introduced into the healing chemistry. Due to the high activity of SbF5, a milder SbF5-ethanol complex with improved processability was prepared, but it was still quite active and cannot be encapsulated by conventional encapsulation techniques like in situ polymerization. Accordingly, a novel route was proposed. Hollow silica microcapsules were firstly synthesized via sol–gel technique, which were then steeped in ethanol solution of SbF5-ethanol complex under vacuum, allowing infiltration of the latter into the capsules. The optimal formulation for creating the hollow silica capsules was studied in detail. Moreover, the results of optical pyrometry demonstrated that the encapsulated chemical retained its high reactivity toward the epoxy.Highly active SbF5-ethanol complex was successfully microencapsulated by using hollow capsules coupled with infiltration.
Co-reporter:Wenkai Zhang, Yujie Chen, Lin Gan, Jian Qing, Xiang Zhou, Yunyun Huang, Yuzhao Yang, Yu Zhang, Jiemei Ou, Xudong Chen, Ming Qiu Zhang
Journal of Physics and Chemistry of Solids 2014 Volume 75(Issue 12) pp:1340-1346
Publication Date(Web):December 2014
DOI:10.1016/j.jpcs.2014.07.013
•Emission of polyfluorene derivatives (PCFOz) is enhanced through LSPR coupling effect.•Ag/PCFOz show blueshifted narrow emission pattern due to LSPR-excitons coupling.•Both light absorption and radiative recombination rate have been enhanced.•The PL enhancement ratio increases with increasing temperature.Polyfluorene-based blue light-emitting devices suffer from the shortcomings of low stability, drastic loss of quantum yield and poor color purity. To find out the solution, we use silver nanoparticles for enhancement of photoluminescence of polyfluorene copolymer (PCFOz) through localized surface plasmon resonance (LSPR) coupling effect. The photoluminescence from PCFOz can be concentrated down to nanoscale, realizing a high spatial selectivity of the fluorescence enhancement process. PL emission of conjugated polymer is blueshifted about 8 nm from the peak emission of 433 nm for the neat PCFOz film to around 425 nm for the Ag/PCFOz composite film. The full width at half maximum of PCFOz is reduced from 88 to 60 nm. Absorbance spectra and time resolved photoluminescence measurements further demonstrate that both absorption intensity and recombination rate of PCFOz increase due to strong LSPR-excitons coupling. Optical properties of such plasmon-enhanced organic light emitters were also studied by temperature-dependent PL spectroscopy from 10 to 200 K. In comparison with bare PCFOz, the LSPR induced emission enhancement ratio significantly increases with increasing temperature. These results are believed to be important for the development of highly efficient blue organic light-emitting devices based on all-solution processing.
Co-reporter:Yunyun Huang;Xudong Chen;Ming Qiu Zhang
Journal of Materials Science 2014 Volume 49( Issue 8) pp:3025-3033
Publication Date(Web):2014 April
DOI:10.1007/s10853-013-8001-6
Graphene films which are fabricated by simple dispensing method without surface modification exhibit reversible switching between superhydrophobicity and superhydrophilicity under alternative UV illumination and dark storage. Careful study of the mechanisms is conducted in view of surface geometry, microstructure, and chemical compositions, and focused on chemical compositions. Photo-induced chemisorption of hydrophilic radicals and water molecules on graphene is found to be responsible for the transition from original hydrophobicity to hydrophilicity, even superhydrophilicity, while replacement of water molecules by oxygen during storage in the dark environment induces the hydrophobicity recovery of graphene films from hydrophilic state. Appearance and disappearance of hydroxyl radicals are closely related to the lattice structure of graphene and energy supply. This wettability conversion is fully reversible. The outcomes not only reveal micro-processes involved in wettability conversion of graphene but also help to purposely design and produce devices from carbon materials with tailor-made tunable surface wettability according to our actual need.
Co-reporter:Chan'e Yuan, Min Zhi Rong, Ming Qiu Zhang
Polymer 2014 Volume 55(Issue 7) pp:1782-1791
Publication Date(Web):1 April 2014
DOI:10.1016/j.polymer.2014.02.033
To provide self-healing ability to polyurethane elastomer, alkoxyamine-based diol was synthesized and reacted with tri-functional homopolymer of hexamethylene diisocyanate (tri-HDI) and polyethylene glycol (PEG). Because alkoxyamines acted as crosslinkers of the resultant polyurethane, the thermally reversible fission/recombination of C–ON bonds in alkoxyamine moieties enabled repeated crosslinking and de-crosslinking of polyurethane chains at certain temperature and hence crack healing. Both qualitative and quantitative characterizations demonstrated that the reversibly crosslinked polyurethane was capable of re-bonding ruptured parts and restoring mechanical strength. The remendability was a function of molecular structure and compositions of the components, which can be purposely tuned according to different application demands.
Co-reporter:Jia Jia Huang, Zhen Feng Zhong, Min Zhi Rong, Xiang Zhou, Xu Dong Chen, Ming Qiu Zhang
Carbon 2014 70() pp: 190-198
Publication Date(Web):
DOI:10.1016/j.carbon.2013.12.092
Co-reporter:Ze Ping Zhang, Min Zhi Rong, Ming Qiu Zhang
Polymer 2014 Volume 55(Issue 16) pp:3936-3943
Publication Date(Web):5 August 2014
DOI:10.1016/j.polymer.2014.06.064
•Crosslinked epoxy acquires room temperature self-healability based on C–ON bonds.•The healability is independent of waiting time prior to cracks reconnection.•A glycidyl-terminated alkoxyamine was synthesized via a novel synthesis route.To provide room temperature self-healing ability to crosslinked epoxy elastomer, alkoxyamine-based diglycidyl ether (DiEPO) is synthesized and cured with polythiol. The C–ON bonds in both the alkoxyamine monomer and the cured epoxy are able to be synchronously cleft and recombined, achieving a dynamic reversible equilibrium state. This habit can thus be used as a healing chemistry for repeatedly re-bonding cracked polymer. Moreover, because the nitrile group that possesses strong capability of adsorbing electrons is attached to the carbon atom of C–ON bonds, homolysis temperature of the alkoxyamine is greatly reduced. The reversible reaction becomes oxygen insensitive in the meantime. As a result, multiple self-healing of the epoxy elastomer in air without manual intervention (heating) is observed by visual inspection and tensile test. Compared to the self-healing crosslinked polymers containing alkoxyamine moieties, which were previously developed in our lab and had to operate at elevated temperature in argon, the current work represents an interesting progress towards practical application in this aspect.
Co-reporter:Jun Ling;Min-zhi Rong;Ming-qiu Zhang 章明秋
Chinese Journal of Polymer Science 2014 Volume 32( Issue 10) pp:1286-1297
Publication Date(Web):2014 October
DOI:10.1007/s10118-014-1522-x
Polyurethanes consisting of tri-functional homopolymer of hexamethylene diisocyanate (tri-HDI) and polyethylene glycol (PEG) are synthesized, in which photo-reversible coumarin moieties act as pendant groups. Accordingly, the polyurethanes can be repeatedly self-healed under UV lights at room temperature by taking advantages of the photodimerization and photocleavage habits of coumarin. Molecular weight of the soft segment, PEG, is found to be closely related to the healing performance of the polyurethanes. Lower molecular weight PEG that corresponds to higher initial coumarin concentration in the polymer is critical for obtaining higher healing efficiency in the case of the first healing action. Nevertheless, it does not guarantee high reversibility of the photo-remendability during the repeated healing events. In contrast, the polyurethane with moderate molecular weight PEG has achieved balanced performance. Reaction kinetics is less important for the healing effect.
Co-reporter:Dong Yu Zhu, Bernd Wetzel, Andreas Noll, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2013 vol. 1(Issue 24) pp:7191-7198
Publication Date(Web):10 Apr 2013
DOI:10.1039/C3TA11008G
Here in this work we propose a thermally molded self-healing thermoplastic polymer containing a multilayer microcapsule-type microreactor. The latter consists of an isolated monomer and catalyst system. As the first proof-of-concept composites, commercial plastics polystyrene (PS) filled with glycidyl methacrylate (GMA)-loaded microreactors are reported. The specially designed structure of the microreactors enables them to be robust enough to survive the thermal processing already widely used in the plastics industry, like melt mixing under shear and compression molding. Upon damage of the composites and microreactors, the GMA monomer is released to the cracks and its atom transfer radical polymerization is triggered when it passes by the catalyst layer. The polymerized GMA serves as a macromolecular adhesive, which not only fills up the interstitial gap of the cracks but also is anchored to the sub-surface of the matrix forming mechanical interlocking, offering satisfactory healing efficiency at room temperature. By changing the species of healing monomer, catalyst and wall substances, the microreactors can meet the versatile requirements of different polymers, so that the approach is provided with broad applicability.
Co-reporter:Wenkai Zhang, Yujie Chen, Chenglong Hu, Yanfeng Zhang, Xudong Chen and Ming Qiu Zhang
Journal of Materials Chemistry A 2013 vol. 1(Issue 6) pp:1265-1271
Publication Date(Web):07 Dec 2012
DOI:10.1039/C2TC00568A
This study demonstrates a novel light-emitting conjugated polymer (PCFOz) used to initiate excitation and propagation of surface plasmon polaritons (SPPs) in silver nanowires. Excitons in the polymer optically excited in close proximity to silver nanowires directly couple to the guided SPPs, and then propagate towards the wires' ends and light up. A tunable exciton–plasmon coupling is realized by varying the distance between PCFOz and Ag nanowires. Strongly efficient excitation of SPPs appears in the case of a spacer thickness of ∼10 nm. Moreover, photobleaching of the organic system is dramatically suppressed by separating the emitter and metal with a spacer, allowing at least 20 times improvement of photostability with a spacer thickness of 25 nm. Spectral dependence of exciton–plasmon coupling indicates that the nanowires' tips contain larger amount of red components. Study of emission decay dynamics demonstrates that the emission properties of PCFOz have been significantly modified by the proximity of Ag nanowires, generating more than 9-fold enhancement of PCFOz spontaneous emission. These results are believed to be important for the development of thin-film photonic–plasmonic waveguides, single photon source and various nanoscale fluorescence sensors.
Co-reporter:Ze Ping Zhang, Min Zhi Rong, Ming Qiu Zhang and Chan'e Yuan
Polymer Chemistry 2013 vol. 4(Issue 17) pp:4648-4654
Publication Date(Web):10 Jun 2013
DOI:10.1039/C3PY00679D
Covalently bonded stiff polyurethane capable of autonomous intrinsic self-healing was synthesized by introducing a specially designed alkoxyamine unit and a soft segment with sub-ambient Tg and high crystallinity into the main chain. The impact and the subsequent healing tests indicated that the polymer can be repeatedly re-bonded at room temperature as characterized by the recovery of impact strengths. The healing process does not need external stimulus and is insensitive to air due to rapid fission and recombination equilibrium of C–ON bonds. Careful investigation about the healing mechanism suggests that inter-diffusion of broken chain fragments across the cracked faces and dynamic reaction of reversible C–ON bonds in the alkoxyamine unit are responsible for crack remending. Owing to the easy tunability of structures of both alkoxyamine and polyurethane, various stiff polymers with similar remendability would be produced according to the principle proposed here in this work.
Co-reporter:Fei Wang, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2012 vol. 22(Issue 26) pp:13076-13084
Publication Date(Web):01 May 2012
DOI:10.1039/C2JM30578J
The C–ON covalent bond with thermally responsive function opens a new avenue to prepare remendable polymers. Carbon-centered radicals and oxygen-centered nitroxide free radicals produced by homolytic cleavage of C–ON bonds at healing temperature synchronously reorganize to form cross-linked networks, offering effective damage repairing characteristics without losing integrity and load bearing ability of the material even above Tg. To gain a deeper understanding of the mechanisms, thermally remendable two-component polymer blends carrying two types of C–ON bonds in the side chains were synthesized. With the aid of small molecule mimetics, intermolecular reactions involved in thermal reversibility of the polymer blends and self-healing capability are analyzed. It was found that crossover reaction between carbon-centered radicals and oxygen-centered nitroxide radicals is necessary, but the possibility of the irreversible combination of carbon-centered radicals should be eliminated. Polymer solid hinders diffusion of carbon-centered radicals so that the unwanted secondary reaction is depressed even though complete recombination of the cleft C–ON bond is also somewhat blocked. Basically, reversibility and multiple self-healing behaviors of the synthesized polymer blends are satisfactory in addition to the expanded healing temperature range. These results are believed to favor materials design and improve crack healing performance based on efficient bond fission and radical recombination.
Co-reporter:Yunyun Huang, Yujie Chen, Chenglong Hu, Bin Zhang, Ting Shen, Xudong Chen and Ming Qiu Zhang
Journal of Materials Chemistry A 2012 vol. 22(Issue 22) pp:10999-11002
Publication Date(Web):25 Apr 2012
DOI:10.1039/C2JM31410J
A facile method for preparing graphene–polyaniline composite is proposed without the necessity of using graphene oxide. By adding CdS nanoparticles into the in situ polymerization system consisting of graphene and aniline monomers, a graphene–polyaniline composite with a well-bonded interface is yielded. It is found that the nano-CdS particles act as a ‘bridge’, connecting (i) PANI via the electrostatic force of attraction between the electron clouds of the sulfur and nitrogen atoms and (ii) graphene by π–π stacking. Taking advantage of the effective interfacial interactions, a large enhancement (∼400%) of the photoelectronic performance in the composite is observed. The work opens up a path for maintaining the original structure and properties of graphene during graphene–polymer composite manufacturing.
Co-reporter:Ming Hui Wang, Wen Hong Ruan, Yi Fu Huang, Lin Ye, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2012 vol. 22(Issue 11) pp:4592-4598
Publication Date(Web):30 Jan 2012
DOI:10.1039/C2JM16097H
With the addition of 1 wt% nanosilica, oriented polypropylene (PP) shows ultra-high tensile strength at break (≈ 320 MPa, stronger than unidirectional glass fiber (∼60 wt%)/PP composites and a low-carbon steel) through solid-state drawing strategy. When nano-SiO2 is present in the drawn PP, the aligned macromolecular chains in amorphous regions can be tied by the well distributed nanofillers to share the stress together. Above the critical content of nanoparticles or drawing ratio, the nanoparticles form a percolated network throughout the matrix, facilitating stress transfer in the amorphous phases during tensile test. Additionally, the nanoparticles favor microfibrillation of the polymer matrix mainly constituted by the crystalline phases. As a result, the high strength covalent bonds of macromolecules in both the amorphous and crystalline phases are brought into full play. Although successful application of adding nanofillers to strengthen polymers is widely spread in rubbers and gels, the increase in strength of semi-crystalline polymers by low aspect ratio nano-inclusion is insignificant up to now. The work is believed to open an avenue for reinforcing semi-crystalline polymers by nanoparticles.
Co-reporter:Zi-Long Wang, Rui Guo, Gao-Ren Li, Han-Lun Lu, Zhao-Qing Liu, Fang-Ming Xiao, Mingqiu Zhang and Ye-Xiang Tong
Journal of Materials Chemistry A 2012 vol. 22(Issue 6) pp:2401-2404
Publication Date(Web):05 Jan 2012
DOI:10.1039/C2JM15070K
Polyaniline (PANI) nanotube arrays were facilely synthesized via electrochemical polymerization in the presence of ZnO nanorod arrays as sacrificial templates, and they were tested as promising flexible electrode materials for supercapacitor applications.
Co-reporter:Bin Zhang, Yujie Chen, Yanfeng Zhang, Xudong Chen, Zhenguo Chi, Jin Yang, Jiemei Ou, Ming Qiu Zhang, Dehao Li, Dong Wang, Mingkai Liu and Juying Zhou
Physical Chemistry Chemical Physics 2012 vol. 14(Issue 13) pp:4640-4650
Publication Date(Web):13 Feb 2012
DOI:10.1039/C2CP23953A
In order to investigate the steric effect of aromatic pendant groups and the electrical bistability in nonconjugated polymers potentially for memory device applications, two π-stacked polymers with different steric structures are synthesized and characterized. They exhibit two conductivity states and can be switched from an initial low-conductivity (OFF) state to a high-conductivity (ON) state. Additionally, they demonstrate nonvolatile write-once-read-many-times (WORM) memory behavior with an ON/OFF current ratio up to 104, and flash memory behavior with an ON/OFF current ratio of approximately 105. Both steady-state and time-resolved fluorescence spectroscopies are used to examine the conformational change of the polymers responding to an applied external electrical voltage. The results provide useful information on different steric effects of pendant groups in polymer chains, resulting in various electrical behaviors. The possibility in realizing an “erasable” behavior through breaking π-stacked structures of pendant groups by a reversal of the electric field was also discussed on the basis of temperature-dependent fluorescence spectroscopy investigation. These results may thus offer a guideline for the design of practical polymer memory devices via tuning steric structure of π-stacked polymers.
Co-reporter:Chenglong Hu, Xudong Chen, Jian Chen, Weihong Zhang and Ming Qiu Zhang
Soft Matter 2012 vol. 8(Issue 17) pp:4780-4787
Publication Date(Web):13 Mar 2012
DOI:10.1039/C2SM07299H
The present work proposed a facile approach to quantify macromolecular migration in micrometer thick polymer films. Using a polystyrene (PS)/poly(methyl methacrylate) (PMMA) binary film as the model material, depth profile analysis was conducted by confocal Raman microscopy (CRM). The results showed mutual diffusion of PS and PMMA molecules across the interface of the immiscible polymer pairs when the binary film had been annealed. In addition, both tracer and mutual diffusion coefficients were determined on the basis of the Fickian model, and the factors that influenced the diffusion behavior were discussed. It is believed that the characterization framework established by the authors has theoretical value and practical meaning.
Co-reporter:Kun Yang;Yu Zhao Yang;Cheng Long Hu;Yun Yun Huang;Wen Kai Zhang;Xu Dong Chen;Ming Qiu Zhang
Macromolecular Chemistry and Physics 2012 Volume 213( Issue 16) pp:1735-1741
Publication Date(Web):
DOI:10.1002/macp.201200090
Abstract
Resonance light scattering (RLS) technique was applied to study macromolecular entanglements in highly dilute poly(vinyl methyl ether) (PVME)/poly(ethylene oxide) (PEO) solution during phase transition process. Temperature dependences of RLS intensities of PVME, PEO and PVME/PEO solutions were recorded. In addition, simulated temperature dependence of RLS intensity of PVME/PEO solution was drawn supposing there was no interaction between PEO and PVME. Comparison between the measured with the simulated results indicated that there were obvious differences in RLS intensities and transition temperatures. The present work proved the existence of entanglements during phase separation in highly dilute solution. Moreover, a model was proposed to describe the entanglement behavior.
Co-reporter:MingQiu Zhang;MinZhi Rong
Science China Chemistry 2012 Volume 55( Issue 5) pp:648-676
Publication Date(Web):2012 May
DOI:10.1007/s11426-012-4511-3
Self-healing polymers represent a class of materials with built-in capability of rehabilitating damages. The topic has attracted increasingly more attention in the past few years. The on-going research activities clearly indicate that self-healing polymeric materials turn out to be a typical multi-disciplinary area concerning polymer chemistry, organic synthesis, polymer physics, theoretical and experimental mechanics, processing, composites manufacturing, interfacial engineering, etc. The present article briefly reviews the achievements of the groups worldwide, and particularly the work carried out in our own laboratory towards strength recovery for structural applications. To ensure sufficient coverage, thermoplastics and thermosetting polymers, extrinsic and intrinsic self-healing, autonomic and non-autonomic healing approaches are included. Innovative routes that correlate materials chemistry to full capacity restoration are discussed for further development from bioinspired toward biomimetic repair.
Co-reporter:Wenzhi Zhang;Xudong Chen;Jin Yang
Polymer Bulletin 2012 Volume 68( Issue 2) pp:425-440
Publication Date(Web):2012 January
DOI:10.1007/s00289-011-0554-4
By using elastic light scattering (ELS) spectroscopy, dependences of lower critical solution temperature (LCST) of poly(vinyl methyl ether) (PVME)/poly(ethylene glycol) (PEG) solutions on concentration (CPEG) and molecular weight of PEG were analyzed. It was found that the onset temperature of phase separation (Tp) decreased with increasing CPEG or molecular weight of PEG in the solutions. It indicated that PEG was competitive with PVME in complexing water molecules. The presence of PEG disturbed the hydration layer around PVME, facilitating the aggregation of PVME chains at lower temperature. Moreover, the ELS spectra revealed the aggregation and dissociation of molecular chains in PVME/PEG solutions during one heating and cooling cycle. PVME chains aggregated above the microphase transition temperature. With further increasing temperature, PVME aggregates started to contract, and then kept stable. During cooling, the chain aggregates were not immediately swelled but gradually swelled, and began to dissociate when the solution temperature was further decreased. Finally, the conformation of the molecular chains returned to its original state.
Co-reporter:Jun Ling, Min Zhi Rong, Ming Qiu Zhang
Polymer 2012 Volume 53(Issue 13) pp:2691-2698
Publication Date(Web):7 June 2012
DOI:10.1016/j.polymer.2012.04.016
A novel polyurethane was synthesized, which consisted of isophorone diisocyanate, polyethylene glycol and photo-reversible moiety 5,7-bis(2-hydroxyethoxy)-4-methylcoumarin. By taking advantage of reversible photodimerization and photocleavage habit of coumarin, the polyurethane can be repeatedly crosslinked and de-crosslinked under successive UV irradiations at 350 and 254 nm. More importantly, damages in crosslinked version of the polyurethane can be re-bonded through chain reconnection on fracture surfaces resulting from the photochemical reactions, as characterized by mechanical strength restoration tests. Compared to the previous proof-of-concept trial with monohydroxyl coumarin derivatives as the photosensitive groups, the application of dihydroxyl coumarin derivatives in the present work prevented the undesirable gelation during synthesis and enabled properties-oriented structure adjustment of polymerization products. Besides, structure–performance relationship study of the polyurethane revealed that rubbery domains resulting from microphase separation were necessary for the photo-remending with high efficiency.
Co-reporter:Ming Qiu Zhang;Min Zhi Rong
Journal of Polymer Science Part B: Polymer Physics 2012 Volume 50( Issue 4) pp:229-241
Publication Date(Web):
DOI:10.1002/polb.22387
Abstract
Bioinspired self-healing polymers have attracted more and more interests. Imparting self-healing ability to existing polymers or developing new polymeric materials capable of self-healing is considered to be a solution for improving their long term stability and durability. This article reviews achievements in the field of theoretical researches on re-establishment of bonding between broken surfaces of self-healing polymers from microscopic and macroscopic point of view. Chains interaction, mechanical models related to healing procedures and effect of healing, design of novel self-healing composite systems, and so forth are summarized and analyzed in detail. Both thermoplastics and thermosets are included to offer a comprehensive knowledge framework of the smart function. The scientific challenges are also highlighted, which are related to the production of more advanced self-healing polymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Co-reporter:Chenglong Hu;Yujie Chen; Xudong Chen;Bin Zhang;Jin Yang;Juying Zhou; Ming Qiu Zhang
Chemistry - A European Journal 2012 Volume 18( Issue 5) pp:1467-1475
Publication Date(Web):
DOI:10.1002/chem.201101769
Abstract
In this paper, the effect of the internal micro-magnetic field (IMMF) on the photocurrent property of conjugated polymer/inorganic semiconductor nanocomposites is reported and analyzed. By using the redox reaction, magnetic Fe3O4 nanoparticles were coated on the surface of highly active nanorods of conjugated polyaniline (PANI), forming an internal micro-magnetic electron donor (i.e., Fe3O4@PANI). After subsequent incorporation of CdS nanoparticles (serving as electron acceptors), the power conversion efficiency (PCE) of the system (Fe3O4@PANI-CdS) was found to be as high as 3.563 %, contrasting sharply with the value (1.135 %) of the hybrid without Fe3O4 (PANI-CdS). This obvious enhancement originated from the fact that the IMMF increased the number of singlet polaron pairs through field-dependent intersystem crossing (ISC), giving a positive contribution to the photocurrent generation. Additionally, the dependence of the photocurrent on the remnant magnetization of the Fe3O4@PANI-CdS nanocomposites was investigated. A percolation behavior was observed, which was due to the appearance of interpenetrating networks consisting of donor and acceptor phases, leading to the recombination of charge carriers through trapping. The outcomes of the present work might help to produce a new family of conjugated organic/inorganic semiconductor nanocomposites with designed optoelectronic performances.
Co-reporter:Chan′e Yuan, Min Zhi Rong, Ming Qiu Zhang, Ze Ping Zhang, and Yan Chao Yuan
Chemistry of Materials 2011 Volume 23(Issue 22) pp:5076
Publication Date(Web):October 21, 2011
DOI:10.1021/cm202635w
The present paper is devoted to preparation of intrinsic self-healing polymeric materials used for structural applications. The authors introduced a novel healing chemistry based on dynamically reversible C–ON bonds, which imitates natural healing in living bodies without affecting their operations. To verify its feasibility, alkoxyamine moieties served as intermolecular links in polystyrene. Upon heating, covalent bond fission and radical recombination synchronously took place among alkoxyamine moieties. Cracked parts were thus reconnected repeatedly, without losing integrity and load bearing ability of the material even above Tg.Keywords: alkoxyamines; cross-linked polymer; self-healing; synchronous reversibility;
Co-reporter:Jun Ling, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2011 vol. 21(Issue 45) pp:18373-18380
Publication Date(Web):18 Oct 2011
DOI:10.1039/C1JM13467A
Coumarin, a traditional perfume substance, serves as a photosensitive crosslinker to construct a polyurethane network. Upon mechanical damage or ultraviolet illumination at a wavelength of 254 nm, the coumarin dimers on the fractured surface that link the polyurethane backbones with one another are cleft, and can be reconnected via irradiation at 350 nm. By using this feature, cracks on the polymer are mended by ultraviolet exposure or even sunlight without the aid of any catalyst. Owing to the reversibility of the photocyclization of coumarin moieties, multiple cycles of crack mending are allowed, as demonstrated by both qualitative and quantitative characterization. This repeated photo-remendability enables the polyurethane to heal the same site in the material more than once, which is of value for practical applications.
Co-reporter:Li Yao, Min Zhi Rong, Ming Qiu Zhang and Yan Chao Yuan
Journal of Materials Chemistry A 2011 vol. 21(Issue 25) pp:9060-9065
Publication Date(Web):18 May 2011
DOI:10.1039/C1JM10655D
To prepare self-healing thermoplastic composites, techniques of living polymerization and microencapsulation were employed. The matrix was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization, in which encapsulated monomer was dispersed. Upon mechanical damage of the composites, the monomer released from broken microcapsules resumed polymerization with the living matrix, establishing chemical bonding between the cracked planes. As a result, full recovery of mechanical strength was achieved at room temperature without manual intervention. Compared to the self-healing material made by atom transfer radical polymerization (ATRP) in the authors' previous work, the present one possesses more meaningful applicability owing to the versatility and robustness of RAFT polymerization.
Co-reporter:Yan Chao Yuan, Xiao Ji Ye, Min Zhi Rong, Ming Qiu Zhang, Gui Cheng Yang, and Jian Qing Zhao
ACS Applied Materials & Interfaces 2011 Volume 3(Issue 11) pp:4487
Publication Date(Web):October 12, 2011
DOI:10.1021/am201182j
To provide self-healing epoxy composite with adequate heat resistance for high-performance application, we developed a novel microencapsulated epoxy/mercaptan healing agent. The key measure lies in usage of diglycidyl ether of bisphenol A (EPON 828) as the polymerizable component and 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30) as the catalyst. Because of the higher thermal stability of EPON 828 and lower volatility of DMP-30, the healing agent and the self-healing composite not only survive high-temperature curing and thermal exposure, but also offer satisfactory capability of autonomous properties restoration, as characterized by both fracture mechanics and fatigue tests. Especially when the operation temperature is not higher than 200 °C, the performance of the healing system is nearly independent of thermal history.Keywords: fatigue; fracture; high-temperature cured epoxy composites; self-healing; thermal stability;
Co-reporter:Kun Yang, Xue Huan Wang, Xu Dong Chen, Ming Qiu Zhang
Polymer 2011 Volume 52(Issue 15) pp:3512-3517
Publication Date(Web):7 July 2011
DOI:10.1016/j.polymer.2011.05.018
To investigate the influence of molecular structure such as side chain on phase separation process in solution, naphthalene-labeled poly (octadecyl vinyl ether) (PODVE) with long side chains was synthesized by living cationic polymerization. Rayleigh Light scattering (RLS) and photoluminescence (PL) studies indicated that side chain played a dominant role in phase separation process in PODVE/dichloromethane system. According to the results of RLS and PL spectra, it was found that PODVE chains changed from expanded coils to collapsed globules and then aggregated. At C = 0.2 g/L, the long side chain of PODVE (102) separated out from nonpolar solvent below 7.2 °C, which directly caused phase separation in solution. In addition, the phase separation temperature slightly increased when the concentration of PODVE (102) solution varies from 0.05 g/L to 0.2 g/L, and more obviously (i.e., from 3.5 °C to 7.2 °C) as the molecular weight increases from 4300 to 10 200. The Activation energy of phase separation of the PODVE solution was −270.09 kJ/mol estimated by means of Avrami equation and Arrhenius formula.The conformational ordering of polymer chain naphthalene-labeled poly(octadecyl vinyl ether) chains in dichloromethane solution was studied by Rayleigh Light scattering technique during cooling process.
Co-reporter:Li Yao, Yan Chao Yuan, Min Zhi Rong, Ming Qiu Zhang
Polymer 2011 Volume 52(Issue 14) pp:3137-3145
Publication Date(Web):22 June 2011
DOI:10.1016/j.polymer.2011.05.024
Self-healing polystyrene (PS) composites were fabricated, in which glycidyl methacrylate (GMA)-loaded microcapsules were embedded. Because the matrix PS was synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization, it kept living characteristics and was able to resume the polymerization so long as monomers were available. Upon damage of the composites, the GMA released from the broken capsules infiltrated into the cracks and was copolymerized with the matrix PS according to the above mechanism. As a result, the cracked planes were covalently re-bonded, offering recovery of impact strength. Compared to the self-healing system based on atom transfer radical polymerization (ATRP), which is also an approach of living polymerization, the current one possesses robust vitality in air and eliminates the possibility of acceleration of matrix degradation aroused by metal ions. Additionally, the resultant self-healing PS composites have an advantage in coloration, which is important for satisfying esthetic requirement in practice.
Co-reporter:Ling Ming Meng, Yan Chao Yuan, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2010 vol. 20(Issue 29) pp:6030-6038
Publication Date(Web):16 Jun 2010
DOI:10.1039/C0JM00268B
A bifunctional single-component healant, glycidyl methacrylate (GMA), is encapsulated and employed for fabricating self-healing epoxy materials. The released GMA is able to rebond cracked portions at room temperature through hydrogen and covalent bonds, and hence recover fracture toughness with high efficiency. The main advances of the healing system lie in the following. (i) It simplifies the conventional approach using two-part healing agent and broadens applicability of the therapy since two healing mechanisms, solvent effect and chemical reactions, are involved. (ii) As GMA contains both epoxide groups and CC bonds, ring-opening and nucleophilic addition reactions between GMA and the residual amine in the matrix occur during crack healing and help to reconnect the separated faces. The application of nucleophilic addition, which has not yet been reported as a healing measure, might lead to expansion of the spectrum of self-healing agent because the species of organic molecules enabling nucleophilic addition reaction are far more than those with specific functional groups like epoxide.
Co-reporter:Jin Yang, Xudong Chen, Ruowen Fu, Wei-ang Luo, Yunbo Li and Mingqiu Zhang
Physical Chemistry Chemical Physics 2010 vol. 12(Issue 9) pp:2238-2245
Publication Date(Web):19 Jan 2010
DOI:10.1039/B918069A
In this work, kinetics of phase separation in the blends of polystyrene (PS) and poly(vinyl methyl ether) (PVME) was investigated by a simple and sensitive method, i.e., resonance light scattering (RLS) spectroscopy. Owing to the aggregation of chromophores (phenyl rings) in the systems when phase separation occurred, RLS intensities were drastically enhanced and hence acted as a characteristic indicator. At the early stage of phase separation, two different RLS behaviors corresponding to spinodal decomposition (SD) and nucleation and growth (NG) were observed. The Cahn-Hilliard (C–H) linearization theory was found not applicable for kinetics analysis of the scattering data at λ < 346 nm due to RLS effect near the absorption band. Based on a decomposition reaction model, the apparent activation energy of SD phase separation was estimated by the Arrhenius equation. In view of its simplicity and sensitivity of measurement, affordability and availability of instrument, and wide application range of polymer blends, RLS proved to be an effective means for characterization of microstructural variation in polymer blends.
Co-reporter:Wei-ang Luo, Xudong Chen, Zhengfu Liao, Jin Yang, Kancheng Mai and Mingqiu Zhang
Physical Chemistry Chemical Physics 2010 vol. 12(Issue 18) pp:4686-4693
Publication Date(Web):19 Mar 2010
DOI:10.1039/B921435F
The dynamic process of cold crystallization of amorphous poly(trimethylene terephthalate) (PTT) was investigated with resonance light scattering (RLS). By using an enhanced scattering peak at 329 nm, which was in close proximity to the absorption band of PTT film, density fluctuation due to gradual transition from amorphous to crystalline with increasing temperature was monitored. Accordingly, molecular chains movement and structure evolution in PTT during cold crystallization, in particular, the information about each phase of crystallization, including induction, nucleation, nucleus growth and secondary crystallization, were thoroughly revealed. The experimental results indicated that the kinetics parameters measured by the RLS method were in good agreement with those obtained by differential scanning calorimetry (DSC) and fluorescence spectroscopy. In addition, the RLS method can tell more details of the movement and variation in fine structures than DSC and fluorescence techniques as a result of its significantly enhanced scattering signals, like the orientation fluctuations of rigid segments in the course of glass transition and crystallization induction.
Co-reporter:Qiao Tian;Min Zhi Rong;Ming Qiu Zhang;Yan Chao Yuan
Polymer International 2010 Volume 59( Issue 10) pp:1339-1345
Publication Date(Web):
DOI:10.1002/pi.2872
Abstract
To produce an epoxy resin with high intrinsic self-healing efficiency, furfurylglycidyl ether (FGE) was synthesized following a two-step route. It carried one furan and one epoxide on each of its molecules. Having been cured using N,N′-(4,4′-diphenylmethane)bismaleimide and methylhexahydrophthalic anhydride, FGE was then polymerized with two types of intermonomer linkages. That is, thermally reversible Diels–Alder (DA) bonds from the reaction between furan and maleimide groups, and thermally irreversible bonds from the reaction between epoxide and anhydride groups. These two types of bonds provide the polymer with thermal remendability and load-bearing capacity, respectively. Compared with N,N-diglycidylfurfurylamine, which was previously developed by the authors and has a similar structure to FGE but with fewer furan rings, FGE can react with maleimide with lower activation energy and the DA bonds formed exhibit higher reversibility. Consequently, improved crack healability of the cured FGE characterized by nearly full recovery of fracture toughness was revealed using double cleavage drilled compression tests. Copyright © 2010 Society of Chemical Industry
Co-reporter:Qiao Tian, Min Zhi Rong, Ming Qiu Zhang, Yan Chao Yuan
Polymer 2010 Volume 51(Issue 8) pp:1779-1785
Publication Date(Web):6 April 2010
DOI:10.1016/j.polymer.2010.02.004
Co-reporter:Hai Ping Wang, Yan Chao Yuan, Min Zhi Rong and Ming Qiu Zhang
Macromolecules 2010 Volume 43(Issue 2) pp:595-598
Publication Date(Web):December 29, 2009
DOI:10.1021/ma902021v
Co-reporter:Wen Zhi Zhang, Xu Dong Chen, Jin Yang, Wei-ang Luo and Ming Qiu Zhang
The Journal of Physical Chemistry B 2010 Volume 114(Issue 3) pp:1301-1306
Publication Date(Web):January 4, 2010
DOI:10.1021/jp909925v
The resonance light scattering (RLS) technique based on a conventional fluorescence spectrophotometer was used to quantitatively describe the aggregation and dissociation of polystyrene (PS) in cyclohexane solution during cyclic heating and cooling. Transitions in conformation of PS molecules and aggregation of PS chains in the course of phase separation were revealed. The results indicated that PS chains changed from random coils to collapsed globules and then aggregated when temperature decreased. In contrast, when the system is heated, the chain aggregates were initially swelled and followed by gradual dissociation. Subsequently, the conformation of PS chains returned to the original state. Kinetics of phase separation of the PS solution was analyzed, which allowed estimation of the apparent activation energy.
Co-reporter:Qing Bing Guo, Kin Tak Lau, Min Zhi Rong, Ming Qiu Zhang
Wear 2010 Volume 269(1–2) pp:13-20
Publication Date(Web):20 May 2010
DOI:10.1016/j.wear.2010.03.001
In the present work, epoxy based quaternary composites were produced by filling lubricant oil-loaded microcapsules, surface grafted nano-SiO2 and discontinuous carbon fibers. Through orthographic tests, the optimal contents of the fillers were determined for achieving significantly improved tribological properties. The lowest specific wear rate and friction coefficient of the composite can be 9.8 × 10−7 mm3/N m and 0.12, respectively, much lower than those of unfilled epoxy, i.e. 1.3 × 10−4 mm3/N m and 0.56. In addition, mechanical properties, especially the maximal loading ability, of the quaternary composite were evidently higher than those of the binary composite with oil-loaded microcapsules. The oil released from the broken microcapsules during sliding wear mainly accounted for the lubrication, while nano-SiO2 and carbon fibers serve as both solid lubricant and reinforcement. As a result, positive synergetic effect appeared and the proposed quaternary composites might be applicable in practice.
Co-reporter:Ding Shu Xiao;Yan Chao Yuan;Min Zhi Rong;Ming Qiu Zhang
Advanced Functional Materials 2009 Volume 19( Issue 14) pp:
Publication Date(Web):
DOI:10.1002/adfm.200990061
Co-reporter:Ding Shu Xiao;Yan Chao Yuan;Min Zhi Rong;Ming Qiu Zhang
Advanced Functional Materials 2009 Volume 19( Issue 14) pp:2289-2296
Publication Date(Web):
DOI:10.1002/adfm.200801827
Abstract
A two-component healing agent, consisting of epoxy-loaded microcapsules and an extremely active catalyst (boron trifluoride diethyl etherate, (C2H5)2O · BF3)), is incorporated into epoxy composites to provide the latter with rapid self-healing capability. To avoid deactivation of the catalyst during composite manufacturing, (C2H5)2O · BF3 is firstly absorbed by fibrous carriers (i.e., short sisal fibers), and then the fibers are coated with polystyrene and embedded in the epoxy matrix together with the encapsulated epoxy monomer. Because of gradual diffusion of the absorbed (C2H5)2O · BF3 from the sisal into the surrounding matrix, the catalyst is eventually distributed throughout the composites and acts as a latent hardener. Upon cracking of the composites, the epoxy monomer is released from the broken capsules, spreading over the cracked planes. As a result, polymerization, triggered by the dispersed (C2H5)2O · BF3, takes place and the damaged sites are rebonded. Since the epoxy–BF3 cure belongs to a cationic chain polymerization, the exact stoichiometric ratio of the reaction components required by other healing chemistries is no longer necessary. Only a small amount of (C2H5)2O · BF3 is sufficient to initiate very fast healing (e.g., a 76% recovery of impact strength is observed within 30 min at 20 °C).
Co-reporter:Jing Hua Chen, Min Zhi Rong, Wen Hong Ruan, Ming Qiu Zhang
Composites Science and Technology 2009 Volume 69(Issue 2) pp:252-259
Publication Date(Web):February 2009
DOI:10.1016/j.compscitech.2008.10.013
The authors proposed an approach for manufacturing nano-SiO2/polypropylene (PP) composites by in situ reactive processing. The key issue lies in that the nanoparticles were covalently bonded to the matrix polymer via polyurethane (PU) elastomer and PP-g-NH2. Unlike the previous techniques based on graft polymerization, the present one did not need to pretreat the nanoparticles. Taking the advantages of rubber-type grafting polymer (i.e. PU) and interfacial reactive compatibilization with PP-g-NH2, a synergetic toughening effect was observed for the PP nanocomposites. Only very low concentrations of nano-SiO2 (1.5–2.5 vol.%) and PU (<4 vol.%) were sufficient to greatly increase notched impact strength of PP. Meanwhile, tensile properties of the nanocomposites were also slightly enhanced.
Co-reporter:Qing Bing Guo;Kin Tak Lau;Bing Fa Zheng;Min Zhi Rong;Ming Qiu Zhang
Macromolecular Materials and Engineering 2009 Volume 294( Issue 1) pp:20-24
Publication Date(Web):
DOI:10.1002/mame.200800257
Co-reporter:Jin Yang, Xudong Chen, Ruowen Fu, Yunbo Li, Wei-ang Luo, Mingqiu Zhang
Polymer Testing 2009 Volume 28(Issue 4) pp:456-460
Publication Date(Web):June 2009
DOI:10.1016/j.polymertesting.2009.03.005
Two-dimensional (2D) correlation resonance light scattering (RLS) spectroscopy has been successfully applied to investigate phase separation of polystyrene (PS)/poly (vinyl methyl ether) (PVME) film by using a conventional spectrofluorimeter. 2D synchronous correlation RLS spectrum indicates that the RLS peak intensity drastically increases with a rise in temperature due to aggregation of chromophores (i.e. phenyl rings) in PS particles in the course of phase separation. In addition, as concluded by 2D asynchronous correlation RLS spectrum, RLS has higher sensitivity than conventional light scattering. For RLS, the closer to the absorption band, the more sensitive it is to the aggregation during phase separation. By means of moving-window two-dimensional (MW2D) correlation spectrum based on autocorrelation calculations, the cloud point (370 K) was determined, which is in good agreement with the literature. On the other hand, time evolution of RLS intensity at various temperatures distinctly shows that phase separation of PS/PVME film involves two mechanisms, i.e. spinodal decomposition (SD) and nucleation and growth (NG). Accordingly, 2D correlation RLS proves to be a very simple and sensitive method to monitor phase separation in polymer blends and might supplement the existing characterization tools.
Co-reporter:Jin Yang, Xudong Chen, Yunbo Li, Weiang Luo, Ruowen Fu, Mingqiu Zhang
Polymer Testing 2009 Volume 28(Issue 2) pp:165-168
Publication Date(Web):April 2009
DOI:10.1016/j.polymertesting.2008.11.009
The synchronous scan spectra (SSS) technique was successfully applied to monitor the macromolecular chain motions near the glass transition temperature in polystyrene (PS) and poly (vinyl methyl ether) (PVME) films on a copper substrate. In SSS of PS and PVME films, two peaks at 467 nm and 473 nm, which correlated to the light source spectrum of the spectrofluorimeter, were used to characterize the glass transition of polymers. By monitoring the intensity of peaks at 467 and 473 nm in the spectra, the intensity-temperature curves exhibited kinks near the glass transition. The kinks have also been shown in plots of IR473/IR467vs. temperature, which implies the distinct fluctuation of SSS intensity distribution at the glass transition temperature of the polymer. As a spectroscopy measurement method with simplicity, rapidity and sensitivity, the SSS method was proved to be able to monitor the glass transition in polymers, which has been commonly measured by differential scanning calorimetry (DSC).
Co-reporter:Xudong Chen, Mingqiu Zhang, Yujie Chen, Dingshan Yu, Baojun Li, Zhiqiu He, Guangji Li
Materials Chemistry and Physics 2009 Volume 118(Issue 1) pp:203-207
Publication Date(Web):15 November 2009
DOI:10.1016/j.matchemphys.2009.07.032
Organic nanowires based on p-hydroxybenzoic acid were synthesized in terms of hydrothermal method. Substrate that is necessary for other nanowires to grow up was no longer needed in the present case. The resultant rod-like nanowires 50–100 nm in diameter and 10–20 μm in length consist of coordinate structure established by complexation between zinc ions, acetoxyl groups and p-hydroxybenzoic acid's carboxyl and phenolic hydroxyl. Through careful observation with scanning electron microscope, it is known that formation of the nanowires experienced nucleation, growing and shaping stages, following vapor–liquid–solid mechanism. The synthetic route is simple, and easy to be monitored owing to the mild reaction conditions. The work might open up new opportunities for nanodevice fabrication with organic nanowires rather than conventional metal and semiconductor ones.
Co-reporter:Wen Zhi Zhang, Xu Dong Chen, Wei-ang Luo, Jin Yang, Ming Qiu Zhang and Fang Ming Zhu
Macromolecules 2009 Volume 42(Issue 5) pp:1720-1725
Publication Date(Web):February 17, 2009
DOI:10.1021/ma802671a
Phase separation and its kinetics of poly (vinyl methyl ether) (PVME) aqueous solutions was investigated by Rayleigh scattering (RS) technique in this work. Concentration dependence of the lower critical solution temperature and time dependence of phase separation were collected, respectively. The RS spectra revealed the transition of molecular conformation and aggregation of molecular chains in the course of phase separation. It was found that upon heating PVME chains changed from expanded coils to collapsed globules and then aggregated. In contrast, during cooling, the chain aggregates were initially swelled and followed by gradual dissociation, while the conformation of molecular chains finally returned to its original state. By means of Avrami equation and Arrhenius formula, apparent activation energy of phase separation of PVME aqueous solutions was estimated. Moreover, a model was proposed to describe the phase separation process.
Co-reporter:Yan Chao Yuan, Min Zhi Rong, Ming Qiu Zhang, Gui Cheng Yang
Polymer 2009 50(24) pp: 5771-5781
Publication Date(Web):
DOI:10.1016/j.polymer.2009.10.019
Co-reporter:Qing Bing Guo, Min Zhi Rong, Guo Liang Jia, Kin Tak Lau, Ming Qiu Zhang
Wear 2009 Volume 266(7–8) pp:658-665
Publication Date(Web):25 March 2009
DOI:10.1016/j.wear.2008.08.005
In the present work, epoxy based composites filled with hybrid nano-SiO2 particles and short pitch based carbon fiber were prepared. Copolymer of styrene and maleic anhydride was grafted onto the nanoparticles prior to the compounding so that the nanoparticles can be covalently connected to the composites’ matrix through the reaction between anhydride and epoxide groups during curing. Consequently, the nano-SiO2/matrix interfacial interaction was enhanced. By evaluating sliding wear properties of the composites as a function of the components concentrations, positive synergetic effect was found. That is, both wear rate and friction coefficient of the hybrid composites were significantly lower than those of the composites containing individual nano-SiO2 or short carbon fiber. The composite with 4 wt.% nano-SiO2 and 6 wt.% carbon fiber offered the greatest improvement of the tribological performance. Compared to the results of hybrid composites reported so far, the above composite is characterized by relatively lower filler content, which would facilitate processing in practice. Increased surface hardness, lubricating effect of the sheet-like wear debris reinforced by nano-SiO2 and rapidly formed transfer film were believed to be the key issues accounting for the remarkable wear resisting and friction reducing behaviors.
Co-reporter:Haiping Wang;Yanchao Yuan;Minzhi Rong
Colloid and Polymer Science 2009 Volume 287( Issue 9) pp:1089-1097
Publication Date(Web):2009 September
DOI:10.1007/s00396-009-2072-6
Melamine-formaldehyde (MF) resin-walled microcapsules containing styrene were prepared by in situ polymerization in an oil-in-water emulsion. In response to the characteristics of styrene (i.e., high volatility, non-polarity, low molecular weight, and low viscosity), the synthesis method was improved by optimizing the reaction conditions accordingly. It was found that utilization of macromolecular emulsifier of lower molecular weight, moderate dispersion rate, and higher feeding weight ratio of core/shell monomers is critical for the fast formation of capsules’ wall. The highest loading of styrene in the resultant microcapsules can be about 60%, and mean diameter of the capsules fell in the range of 20∼71 μm, which can be adjusted by changing processing parameters. It is believed that the present work provides a feasible approach to encapsulate monomers for manufacturing polyester based self-healing composites.
Co-reporter:Jing Hua Chen;Min Zhi Rong;Wen Hong Ruan;Yu Liang Mai;Ming Qiu Zhang
Macromolecular Chemistry and Physics 2008 Volume 209( Issue 17) pp:1826-1835
Publication Date(Web):
DOI:10.1002/macp.200800091
Co-reporter:Wei-ang Luo, Yujie Chen, Xudong Chen, Zhengfu Liao, Kancheng Mai and Mingqiu Zhang
Macromolecules 2008 Volume 41(Issue 11) pp:3912-3918
Publication Date(Web):May 10, 2008
DOI:10.1021/ma8000059
Photoinduced energy transfer in poly(trimethylene terephthalate) (PTT) was investigated by examining its excitation wavelength and concentration dependences of fluorescence in solutions. Accordingly, critical quench concentration and critical trap formation concentration were identified. Besides, studies of temperature effect on photoluminescence (PL) behavior of amorphous PTT film from −183 to +177 °C revealed that both fluorescence and phosphorescence emissions at low temperature can be attributed to monomers and traps. Phosphorescence quenching originated from the discontinuous increase of nonradiative processes. The corresponding quenching activation energies were estimated to be 13.5 kJ/mol for monomer phosphorescence quenching and 17.2 kJ/mol for exciplex phosphorescence quenching, respectively. Furthermore, the PL method proved to be able to monitor molecular relaxations (including γ-, β-, and α-transitions) and cold crystallization in PTT film, which used to be measured by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC), respectively.
Co-reporter:Yan Chao Yuan, Min Zhi Rong, Ming Qiu Zhang, Jian Chen, Gui Cheng Yang and Xue Mei Li
Macromolecules 2008 Volume 41(Issue 14) pp:5197-5202
Publication Date(Web):June 27, 2008
DOI:10.1021/ma800028d
A self-healing system based on conventional epoxy resin was successfully developed in this work. Epoxy and its hardener mercaptan were microencapsulated as two-component healing agent, and then the microcapsules were embedded in epoxy matrix. Attractive healing effect can be acquired at low capsule content (e.g., 43.5% healing efficiency with 1 wt % capsules and 104.5% healing efficiency with 5 wt % capsules at 20 °C for 24 h). Since only a few healant proves to be sufficient for crack repairing, a better balance between strength and toughness restoration can thus be achieved. As a result of high flowability, fast consolidation, and molecular miscibility of the released healing agent consisting of epoxy and mercaptan, self-healing was allowed to proceed rapidly offering satisfactory repair effectiveness.
Co-reporter:Wei-ang Luo, Zhengfu Liao, Jin Yan, Yunbo Li, Xudong Chen, Kancheng Mai and Mingqiu Zhang
Macromolecules 2008 Volume 41(Issue 20) pp:7513-7518
Publication Date(Web):September 26, 2008
DOI:10.1021/ma801119n
Dynamic processes of isothermally cold-crystallized poly(trimethylene terephthalate) (PTT) was investigated by fluorescence spectroscopy of its amorphous region. The key issue lay in the fact that the emission at 390 nm originating from the main chain phenylene ring in the amorphous phase was correlated to the cold-crystallization. A reduction in this emission peak intensity corresponded to a gradual transition of the phenylene ring in the amorphous to crystal region. Accordingly, molecular chain movement and structure evolution of PTT in the course of cold-crystallization were carefully revealed. The experimental results indicated that the kinetics parameters measured by the fluorescence spectroscopy method are in good agreement with those by differential scanning calorimetry (DSC). What is more, the former was capable of providing detailed information about structural variations during cold-crystallization, for example, molecule arrangement in induction phase.
Co-reporter:Tao Yin, Min Zhi Rong, Jingshen Wu, Haibin Chen, Ming Qiu Zhang
Composites Part A: Applied Science and Manufacturing 2008 Volume 39(Issue 9) pp:1479-1487
Publication Date(Web):September 2008
DOI:10.1016/j.compositesa.2008.05.010
Woven glass fabric reinforced epoxy composite laminates were provided with crack healing capability by pre-dispersing a novel repair system in the composites’ matrix. The healing agent consisted of epoxy-loaded microcapsules and latent hardener CuBr2(2-MeIm)4 (the complex of CuBr2 and 2-methylimidazole). Compression after impact (CAI) tests were conducted to evaluate mechanical performance of the laminates before and after crack healing. Moreover, healing efficiency was studied as a function of impact energy, repair pressure, content and size of the microencapsulated epoxy. The experimental results indicated that the healing agent worked in repairing matrix cracks generated by impact. The composites should be heated to 140 °C for 0.5 h to achieve healing and moderate pressure was needed to close larger crack damage for good healing.
Co-reporter:T. H. Zhou;M. Z. Rong;W. H. Ruan;M. Q. Zhang;Y. L. Mai
Advanced Materials 2007 Volume 19(Issue 18) pp:2667-2671
Publication Date(Web):22 AUG 2007
DOI:10.1002/adma.200602611
A strategy for improving mobility of non-layered nanoparticles in a polymer matrix is proposed by reducing the interparticulate attraction and enhancing filler/matrix interaction in the rubbery state of the matrix, which induces additional energy dissipation mechanisms and increases toughness of the composites.
Co-reporter:Xudong Chen, Yeping Dong, Li Fan, Dacheng Yang, Mingqiu Zhang
Analytica Chimica Acta 2007 Volume 597(Issue 2) pp:300-305
Publication Date(Web):10 August 2007
DOI:10.1016/j.aca.2007.07.008
Resonance light scattering (RLS) of the functionalized ZnS nanocrystals–peptides system and its analytical application have been studied. The RLS intensity can be efficiently enhanced when various peptides were added. The mechanism of the RLS enhancement of ZnS nanocrystals was discussed. The change of RLS intensity was in proportion to the concentration of peptides. The limits of detection were in range of 2.8–5.7 ng mL−1. Application results to synthetic samples showed simplicity, rapidity, high sensitivity and satisfactory reproducibility of the presented method. Measurements of real samples also give satisfactory results which were in good agreement with those obtained using high performance liquid chromatography (HPLC) and liquid chromatography–mass spectrography (LC–MS) methods.
Co-reporter:Wen Hong Ruan, Yu Liang Mai, Xian Hou Wang, Min Zhi Rong, Ming Qiu Zhang
Composites Science and Technology 2007 Volume 67(Issue 13) pp:2747-2756
Publication Date(Web):October 2007
DOI:10.1016/j.compscitech.2007.02.004
To improve the performance of nanoparticles/thermoplastics composites, a pre-drawing technique was developed in the authors’ lab. Nanoparticles were firstly modified by graft polymerization, and then the grafted nanoparticles were melt-compounded with a matrix polymer and stretched to produce composite filaments. Finally, the filaments were injection molded into bulk materials. Because the filamentation-induced separation of the nanoparticle agglomerates can be kept in the course of re-molding due to the interaction between the grafted polymer and the matrix, the nanoparticles were uniformly dispersed in the ultimate composites. As a result, an overall enhancement of tensile and notched impact properties of the composites was acquired. The present work systematically investigated influences of the key factors (percent grafting of the grafted nanoparticles and draw ratio) on structure and properties of nano-SiO2/polypropylene composites. It was found that draw ratio set for filamentation should match the amount of the grafted polymer (i.e. percent grafting) for purposes of giving full play to the pre-drawing technique. The composites’ microstructure and performance as well could be tuned by changing the processing conditions.
Co-reporter:Habibah Ghazali, Lin Ye, Ming Q. Zhang
Composites Science and Technology (12 April 2017) Volume 142() pp:
Publication Date(Web):12 April 2017
DOI:10.1016/j.compscitech.2017.02.018
The effects of microcapsules containing healing resins on the Mode II interlaminar fracture toughness (GIIC) of carbon fibre/epoxy composite laminates were investigated using end-notched flexure (ENF) specimens. The results indicate that the Mode II interlaminar fracture toughness of the original CF/EP laminates was improved with the incorporation of a dual-component microencapsulated self-healant. It was observed that the microcapsules induced toughening via two mechanism: i) larger plastic deformation due to a thicker resin-rich interlaminar region and ii) microcapsules in tempering hackle formation. When subjected to healing after release of the microencapsulated resins, the dual-component healant provided the laminates with 63% healing efficiency in Mode II interlaminar fracture toughness. Observation of fracture surfaces using scanning electron microscopy also revealed that the healing efficiency varied directly with the concentration of healant and subsequently the formation of a dense interlaminar region after the original fracture.
Co-reporter:Ling Ming Meng, Yan Chao Yuan, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 29) pp:NaN6038-6038
Publication Date(Web):2010/06/16
DOI:10.1039/C0JM00268B
A bifunctional single-component healant, glycidyl methacrylate (GMA), is encapsulated and employed for fabricating self-healing epoxy materials. The released GMA is able to rebond cracked portions at room temperature through hydrogen and covalent bonds, and hence recover fracture toughness with high efficiency. The main advances of the healing system lie in the following. (i) It simplifies the conventional approach using two-part healing agent and broadens applicability of the therapy since two healing mechanisms, solvent effect and chemical reactions, are involved. (ii) As GMA contains both epoxide groups and CC bonds, ring-opening and nucleophilic addition reactions between GMA and the residual amine in the matrix occur during crack healing and help to reconnect the separated faces. The application of nucleophilic addition, which has not yet been reported as a healing measure, might lead to expansion of the spectrum of self-healing agent because the species of organic molecules enabling nucleophilic addition reaction are far more than those with specific functional groups like epoxide.
Co-reporter:Nan Nan Xia, Xiao Min Xiong, Junhu Wang, Min Zhi Rong and Ming Qiu Zhang
Chemical Science (2010-Present) 2016 - vol. 7(Issue 4) pp:
Publication Date(Web):
DOI:10.1039/C5SC03483C
Co-reporter:Bin Zhang, Yujie Chen, Yanfeng Zhang, Xudong Chen, Zhenguo Chi, Jin Yang, Jiemei Ou, Ming Qiu Zhang, Dehao Li, Dong Wang, Mingkai Liu and Juying Zhou
Physical Chemistry Chemical Physics 2012 - vol. 14(Issue 13) pp:NaN4650-4650
Publication Date(Web):2012/02/13
DOI:10.1039/C2CP23953A
In order to investigate the steric effect of aromatic pendant groups and the electrical bistability in nonconjugated polymers potentially for memory device applications, two π-stacked polymers with different steric structures are synthesized and characterized. They exhibit two conductivity states and can be switched from an initial low-conductivity (OFF) state to a high-conductivity (ON) state. Additionally, they demonstrate nonvolatile write-once-read-many-times (WORM) memory behavior with an ON/OFF current ratio up to 104, and flash memory behavior with an ON/OFF current ratio of approximately 105. Both steady-state and time-resolved fluorescence spectroscopies are used to examine the conformational change of the polymers responding to an applied external electrical voltage. The results provide useful information on different steric effects of pendant groups in polymer chains, resulting in various electrical behaviors. The possibility in realizing an “erasable” behavior through breaking π-stacked structures of pendant groups by a reversal of the electric field was also discussed on the basis of temperature-dependent fluorescence spectroscopy investigation. These results may thus offer a guideline for the design of practical polymer memory devices via tuning steric structure of π-stacked polymers.
Co-reporter:Wenkai Zhang, Yujie Chen, Chenglong Hu, Yanfeng Zhang, Xudong Chen and Ming Qiu Zhang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 6) pp:NaN1271-1271
Publication Date(Web):2012/12/07
DOI:10.1039/C2TC00568A
This study demonstrates a novel light-emitting conjugated polymer (PCFOz) used to initiate excitation and propagation of surface plasmon polaritons (SPPs) in silver nanowires. Excitons in the polymer optically excited in close proximity to silver nanowires directly couple to the guided SPPs, and then propagate towards the wires' ends and light up. A tunable exciton–plasmon coupling is realized by varying the distance between PCFOz and Ag nanowires. Strongly efficient excitation of SPPs appears in the case of a spacer thickness of ∼10 nm. Moreover, photobleaching of the organic system is dramatically suppressed by separating the emitter and metal with a spacer, allowing at least 20 times improvement of photostability with a spacer thickness of 25 nm. Spectral dependence of exciton–plasmon coupling indicates that the nanowires' tips contain larger amount of red components. Study of emission decay dynamics demonstrates that the emission properties of PCFOz have been significantly modified by the proximity of Ag nanowires, generating more than 9-fold enhancement of PCFOz spontaneous emission. These results are believed to be important for the development of thin-film photonic–plasmonic waveguides, single photon source and various nanoscale fluorescence sensors.
Co-reporter:Zi-Long Wang, Rui Guo, Gao-Ren Li, Han-Lun Lu, Zhao-Qing Liu, Fang-Ming Xiao, Mingqiu Zhang and Ye-Xiang Tong
Journal of Materials Chemistry A 2012 - vol. 22(Issue 6) pp:NaN2404-2404
Publication Date(Web):2012/01/05
DOI:10.1039/C2JM15070K
Polyaniline (PANI) nanotube arrays were facilely synthesized via electrochemical polymerization in the presence of ZnO nanorod arrays as sacrificial templates, and they were tested as promising flexible electrode materials for supercapacitor applications.
Co-reporter:Fei Wang, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 26) pp:NaN13084-13084
Publication Date(Web):2012/05/01
DOI:10.1039/C2JM30578J
The C–ON covalent bond with thermally responsive function opens a new avenue to prepare remendable polymers. Carbon-centered radicals and oxygen-centered nitroxide free radicals produced by homolytic cleavage of C–ON bonds at healing temperature synchronously reorganize to form cross-linked networks, offering effective damage repairing characteristics without losing integrity and load bearing ability of the material even above Tg. To gain a deeper understanding of the mechanisms, thermally remendable two-component polymer blends carrying two types of C–ON bonds in the side chains were synthesized. With the aid of small molecule mimetics, intermolecular reactions involved in thermal reversibility of the polymer blends and self-healing capability are analyzed. It was found that crossover reaction between carbon-centered radicals and oxygen-centered nitroxide radicals is necessary, but the possibility of the irreversible combination of carbon-centered radicals should be eliminated. Polymer solid hinders diffusion of carbon-centered radicals so that the unwanted secondary reaction is depressed even though complete recombination of the cleft C–ON bond is also somewhat blocked. Basically, reversibility and multiple self-healing behaviors of the synthesized polymer blends are satisfactory in addition to the expanded healing temperature range. These results are believed to favor materials design and improve crack healing performance based on efficient bond fission and radical recombination.
Co-reporter:Zhou Qiao Lei, Pu Xie, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 39) pp:NaN19668-19668
Publication Date(Web):2015/09/03
DOI:10.1039/C5TA05788D
The present work reveals that catalyst-free dynamic reversible exchange of aromatic Schiff base bonds is enabled at room temperature. Attachment of aryl groups to both nitrogen and carbon atoms of carbon–nitrogen double bonds is a critical structural factor that contributes to the dynamic characteristics and complete reaction between aromatic aldehyde and aromatic amine. The exchange mechanism is studied by model compounds, and free radical intermediates are found to be involved in the non-equilibrium stage of the exchange reaction. By taking advantage of the dynamic equilibrium of aromatic Schiff base bonds, infusible and insoluble crosslinked polyacrylate is self-healed and reprocessed through rearrangement of macromolecular networks. The reprocessed polymer is still self-healable. Either the self-healing or reprocessing is completed in air without heating. Considering that Schiff base polymers have shown diverse properties and stimulus–response behaviors, activation of the dynamic exchange of the inherent Schiff base bonds would result in a series of novel functionalities. More interestingly, traditional crosslinked polymers might thus be provided with a facile way of being smarter.
Co-reporter:Ming Hui Wang, Wen Hong Ruan, Yi Fu Huang, Lin Ye, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 11) pp:NaN4598-4598
Publication Date(Web):2012/01/30
DOI:10.1039/C2JM16097H
With the addition of 1 wt% nanosilica, oriented polypropylene (PP) shows ultra-high tensile strength at break (≈ 320 MPa, stronger than unidirectional glass fiber (∼60 wt%)/PP composites and a low-carbon steel) through solid-state drawing strategy. When nano-SiO2 is present in the drawn PP, the aligned macromolecular chains in amorphous regions can be tied by the well distributed nanofillers to share the stress together. Above the critical content of nanoparticles or drawing ratio, the nanoparticles form a percolated network throughout the matrix, facilitating stress transfer in the amorphous phases during tensile test. Additionally, the nanoparticles favor microfibrillation of the polymer matrix mainly constituted by the crystalline phases. As a result, the high strength covalent bonds of macromolecules in both the amorphous and crystalline phases are brought into full play. Although successful application of adding nanofillers to strengthen polymers is widely spread in rubbers and gels, the increase in strength of semi-crystalline polymers by low aspect ratio nano-inclusion is insignificant up to now. The work is believed to open an avenue for reinforcing semi-crystalline polymers by nanoparticles.
Co-reporter:Yunyun Huang, Yujie Chen, Chenglong Hu, Bin Zhang, Ting Shen, Xudong Chen and Ming Qiu Zhang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 22) pp:
Publication Date(Web):
DOI:10.1039/C2JM31410J
Co-reporter:Dong Yu Zhu, Bernd Wetzel, Andreas Noll, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 24) pp:NaN7198-7198
Publication Date(Web):2013/04/10
DOI:10.1039/C3TA11008G
Here in this work we propose a thermally molded self-healing thermoplastic polymer containing a multilayer microcapsule-type microreactor. The latter consists of an isolated monomer and catalyst system. As the first proof-of-concept composites, commercial plastics polystyrene (PS) filled with glycidyl methacrylate (GMA)-loaded microreactors are reported. The specially designed structure of the microreactors enables them to be robust enough to survive the thermal processing already widely used in the plastics industry, like melt mixing under shear and compression molding. Upon damage of the composites and microreactors, the GMA monomer is released to the cracks and its atom transfer radical polymerization is triggered when it passes by the catalyst layer. The polymerized GMA serves as a macromolecular adhesive, which not only fills up the interstitial gap of the cracks but also is anchored to the sub-surface of the matrix forming mechanical interlocking, offering satisfactory healing efficiency at room temperature. By changing the species of healing monomer, catalyst and wall substances, the microreactors can meet the versatile requirements of different polymers, so that the approach is provided with broad applicability.
Co-reporter:Jin Yang, Xudong Chen, Ruowen Fu, Wei-ang Luo, Yunbo Li and Mingqiu Zhang
Physical Chemistry Chemical Physics 2010 - vol. 12(Issue 9) pp:NaN2245-2245
Publication Date(Web):2010/01/19
DOI:10.1039/B918069A
In this work, kinetics of phase separation in the blends of polystyrene (PS) and poly(vinyl methyl ether) (PVME) was investigated by a simple and sensitive method, i.e., resonance light scattering (RLS) spectroscopy. Owing to the aggregation of chromophores (phenyl rings) in the systems when phase separation occurred, RLS intensities were drastically enhanced and hence acted as a characteristic indicator. At the early stage of phase separation, two different RLS behaviors corresponding to spinodal decomposition (SD) and nucleation and growth (NG) were observed. The Cahn-Hilliard (C–H) linearization theory was found not applicable for kinetics analysis of the scattering data at λ < 346 nm due to RLS effect near the absorption band. Based on a decomposition reaction model, the apparent activation energy of SD phase separation was estimated by the Arrhenius equation. In view of its simplicity and sensitivity of measurement, affordability and availability of instrument, and wide application range of polymer blends, RLS proved to be an effective means for characterization of microstructural variation in polymer blends.
Co-reporter:Jia Jia Huang, Min Zhi Rong and Ming Qiu Zhang
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 6) pp:NaN4806-4806
Publication Date(Web):2016/01/14
DOI:10.1039/C5CP06582H
A simple, effective and green bottom-up method for the synthesis of highly fluorescent N doped graphene oxide quantum dots (GOQDs) and polymer-like quantum dots (PQDs) was developed on the basis of rapid one-step microwave assisted pyrolysis of citric acid (CA) and diethylenetriamine (DETA) in different reaction solvents. Both one-photon-induced and two-photon-induced photoluminescence (PL) properties of the resultant GOQDs and PQDs were characterized and analyzed. The one-photon-induced PL quantum yields (QY) of GOQDs and PQDs reached 39.8 and 74.0%, respectively, which are high enough to exhibit strong photoluminescence (PL) emission even under daylight excitation. The origin of the PL behavior and PL quenching mechanism was explored in terms of the interaction between the functional groups on the surfaces of GOQDs or PQDs and Hg2+. Furthermore, due to the excellent selectivity and sensitivity of the GOQDs and PQDs to Hg2+, the quantum dots might be used for quantitative detection of Hg2+ in aqueous solution.
Co-reporter:Jun Ling, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2011 - vol. 21(Issue 45) pp:NaN18380-18380
Publication Date(Web):2011/10/18
DOI:10.1039/C1JM13467A
Coumarin, a traditional perfume substance, serves as a photosensitive crosslinker to construct a polyurethane network. Upon mechanical damage or ultraviolet illumination at a wavelength of 254 nm, the coumarin dimers on the fractured surface that link the polyurethane backbones with one another are cleft, and can be reconnected via irradiation at 350 nm. By using this feature, cracks on the polymer are mended by ultraviolet exposure or even sunlight without the aid of any catalyst. Owing to the reversibility of the photocyclization of coumarin moieties, multiple cycles of crack mending are allowed, as demonstrated by both qualitative and quantitative characterization. This repeated photo-remendability enables the polyurethane to heal the same site in the material more than once, which is of value for practical applications.
Co-reporter:Yunyun Huang, Wensheng Lin, Kan Chen, Wenkai Zhang, Xudong Chen and Ming Qiu Zhang
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 23) pp:
Publication Date(Web):
DOI:10.1039/C4CP00773E
Co-reporter:Wei-ang Luo, Xudong Chen, Zhengfu Liao, Jin Yang, Kancheng Mai and Mingqiu Zhang
Physical Chemistry Chemical Physics 2010 - vol. 12(Issue 18) pp:NaN4693-4693
Publication Date(Web):2010/03/19
DOI:10.1039/B921435F
The dynamic process of cold crystallization of amorphous poly(trimethylene terephthalate) (PTT) was investigated with resonance light scattering (RLS). By using an enhanced scattering peak at 329 nm, which was in close proximity to the absorption band of PTT film, density fluctuation due to gradual transition from amorphous to crystalline with increasing temperature was monitored. Accordingly, molecular chains movement and structure evolution in PTT during cold crystallization, in particular, the information about each phase of crystallization, including induction, nucleation, nucleus growth and secondary crystallization, were thoroughly revealed. The experimental results indicated that the kinetics parameters measured by the RLS method were in good agreement with those obtained by differential scanning calorimetry (DSC) and fluorescence spectroscopy. In addition, the RLS method can tell more details of the movement and variation in fine structures than DSC and fluorescence techniques as a result of its significantly enhanced scattering signals, like the orientation fluctuations of rigid segments in the course of glass transition and crystallization induction.
Co-reporter:Wei Min Xu, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 27) pp:NaN10690-10690
Publication Date(Web):2016/06/13
DOI:10.1039/C6TA02662A
For realizing sunlight stimulated self-healing, a crosslinked polyurethane carrying disulfide in the main chain is synthesized. Its macromolecular composition and architecture are optimized so that the included disulfide bonds can take part in the exchange reaction simply under illumination of the low concentration UV component of sunlight. Accordingly, the damaged polymer is allowed to be repeatedly healed in the sun in terms of strength restoration as a result of photo-triggered reversible exchange of disulfide bonds. Meanwhile, the elaborately introduced hydrogen bonding helps to quickly close cracks, favoring intimate contacts of the cracked surface and subsequent interaction of dangling chains across the interface, and eventually raising the effectiveness of the photo-reaction of the disulfide bonds in the solid phase. In addition, network rearrangement due to disulfide exchange enables multiple recycling and reshaping of the polymer under sunshine. The present proof-of-concept work would be hopefully developed into a cost-effective and environmentally friendly technology of design, fabrication and application of smart photo-sensitive polymers with high mechanical strength.
Co-reporter:Dong Yu Zhu, Jian Wei Guo, Guang Sheng Cao, Wen Lian Qiu, Min Zhi Rong and Ming Qiu Zhang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 5) pp:NaN1862-1862
Publication Date(Web):2014/12/11
DOI:10.1039/C4TA06381C
Commercially available polystyrene is coupled with self-healability by exploiting a novel healing chemistry of redox cationic polymerization. In this system, iodonium bis(4-methylphenyl) hexafluorophosphate (IBH)/glycidyl methacrylate (GMA) loaded microcapsules and NaBH4 particles are embedded in the matrix through compression molding. The healant is oxygen insensitive and heat resistant so that it meets the requirement of remendable thermoplastics.
Co-reporter:Wei Hong, Yu Zhang, Lin Gan, Xudong Chen and Mingqiu Zhang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 24) pp:NaN6191-6191
Publication Date(Web):2015/05/14
DOI:10.1039/C5TC00464K
Ordered arrays of Ag-capped colloidal crystals were fabricated and modified with conjugated polymers to evaluate the excitation and emission fluorescence enhancement due to localized surface plasmon resonance (LSPR). The maximum enhancement accrued on the maximum overlap between the excitation wavelength and LSPRs of the substrates. The observed fluorescence enhancement and lifetime measurement showed that the large enhancement came from a combination of greatly enhanced excitation and an increased radiative decay rate, leading to an associated enhancement of the quantum efficiency. Thus, such Ag nanostructured arrays fabricated by colloidal lithograph show great potential for biosensing and photovoltaic applications, and the excitation wavelength–LSPR-based fluorescence enhancement proves useful for understanding and optimizing metal-enhanced fluorescence.
Co-reporter:Li Yao, Min Zhi Rong, Ming Qiu Zhang and Yan Chao Yuan
Journal of Materials Chemistry A 2011 - vol. 21(Issue 25) pp:NaN9065-9065
Publication Date(Web):2011/05/18
DOI:10.1039/C1JM10655D
To prepare self-healing thermoplastic composites, techniques of living polymerization and microencapsulation were employed. The matrix was synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization, in which encapsulated monomer was dispersed. Upon mechanical damage of the composites, the monomer released from broken microcapsules resumed polymerization with the living matrix, establishing chemical bonding between the cracked planes. As a result, full recovery of mechanical strength was achieved at room temperature without manual intervention. Compared to the self-healing material made by atom transfer radical polymerization (ATRP) in the authors' previous work, the present one possesses more meaningful applicability owing to the versatility and robustness of RAFT polymerization.
Co-reporter:Chan'e Yuan, Ming Qiu Zhang and Min Zhi Rong
Journal of Materials Chemistry A 2014 - vol. 2(Issue 18) pp:NaN6566-6566
Publication Date(Web):2014/02/06
DOI:10.1039/C4TA00130C
To provide epoxy with intrinsic self-healing ability, a new alkoxyamine based diol was synthesized and incorporated into an epoxy monomer, which was then compounded with traditional bisphenol A diglycidyl ether and cured by diethylenetriamine. Taking advantage of dynamic equilibrium of thermally reversible reaction of C–ON bond in alkoxyamine, cracked portions of the functionalized epoxy material can be repeatedly reconnected at certain temperature, as characterized by restoration of impact strength and visual inspection as well. Unlike the two-step self-healing approach based on reversible Diels–Alder reaction, the present one only needed one step. Owing to the steric hindrance of tertiary butyl group in the diol, onset of scission of C–ON bonds and radical recombination (i.e., healing reaction) occurred at lower temperature. Additionally, reversibility of the alkoxyamine derivatives was improved with incorporation of Si–O bonds into the epoxy chains. The present work carefully studied thermal reversibility, thermal stability, dynamic mechanical behavior and healing performance of the epoxy in relation to molecular structure. The outcomes might help to optimize the material and guide future design of novel epoxy monomers.
Co-reporter:Yangfan Zhang, Yunhong Tan, Kang Yang, Zexiong Wu, Zishou Zhang, Mingqiu Zhang and Kancheng Mai
Journal of Materials Chemistry A 2016 - vol. 4(Issue 26) pp:NaN10097-10097
Publication Date(Web):2016/04/29
DOI:10.1039/C6TA02161A
Molecular chain bonding is, for the first time, developed to synthesize a nanoporous, flexible and conductive polymer composite by converting a single polymer phase matrix to two phases of interpenetrating polymer networks. Significantly, the porous polymer composite not only presents ultra-high mechanical properties, durability and conductive stability, but also enhances the capacitance by 7-fold.
