Co-reporter:Ye Fu, Congcong Gong, Wencai Wang, Liqun Zhang, Evgenii Ivanov, and Yuri Lvov
ACS Applied Materials & Interfaces September 6, 2017 Volume 9(Issue 35) pp:30083-30083
Publication Date(Web):August 16, 2017
DOI:10.1021/acsami.7b09677
An antifouling ethylene-vinyl acetate copolymer (EVA) coating with halloysite clay nanotubes loaded with maleimide (TCPM) is prepared. Such antifoulant encapsulation allowed for extended release of TCPM and a long-lasting, efficient protection of the coated surface against marine microorganisms proliferation. Halloysite also induces the composite’s anisotropy due to parallel alignment of the nanotubes. The maleimide loaded halloysite incorporated into the polymer matrix allowed for 12-month release of the bacterial inhibitor preventing fouling; it is much longer than the 2–3 month protection when TCPM is directly admixed into EVA. The antifouling properties of the EVA-halloysite nanocomposites were tested by monitoring surface adhesion and proliferation of marine V. natriegens bacteria with SEM. As compared to the composite directly doped with TCPM-antifoulant, there were much less bacteria accumulated on the EVA-halloysite-TCPM coating after a 2-month exposure to seawater. Field tests at South China Sea marine station further confirmed the formulation efficiency. The doping of 28 wt % TCPM loaded halloysite drastically enhanced material antifouling property, which promises wide applications for protective marine coating.Keywords: halloysite; marine antifouling; nanotubes; sustained release; thermoplastic;
Co-reporter:Ye Fu, Chun Yang, Yuri M. Lvov, Liqun Zhang, Wencai Wang
Chemical Engineering Journal 2017 Volume 328(Volume 328) pp:
Publication Date(Web):15 November 2017
DOI:10.1016/j.cej.2017.06.142
•A method to load antioxidant into carbon nanotubes for sustained release is proposed.•The sustained release of antioxidant from carbon nanotubes extends its action time.•The antioxidant amount in the rubber composite is enlarged without causing blooming.•The thermal-oxidative & ozone aging resistance of SBR/CNTs is improved.In this work, a novel strategy to avoid the blooming of antioxidants and improve the aging-resistance of styrene-butadiene rubber (SBR) was proposed by using carbon nanotubes (CNTs) loaded with antioxidant N-(1, 3-dimethyl) butyl-N′-phenyl-p-phenylenediamine (4020) as filler. The sustained release of antioxidant from carbon nanotubes extends its action time. The amount of antioxidant in the rubber composites allows for a concentration of 2.0 wt.% without causing blooming by encapsulating antioxidant into carbon nanotubes. The aging resistance of SBR/CNTs composites was studied by comparing the mechanical properties before and after thermal-oxidative and ozone aging. A fifteen-day thermal-oxidative aging test at 100 °C shows preservation of mechanical properties and a twenty-four-hour ozone aging test shows no cracks. Furthermore, due to the present of thermal and electrical conductive carbon nanotubes, the rubber composites emerge thermal conductivity of 0.303 W/m·K and electrical conductivity of 4.74 × 107 Ω·cm which can be extended for many potential applications, such as long service life tires and antistatic conveyer belts. This loading and sustained release approach can be extended to antimicrobial, antifouling, and other application.Download high-res image (140KB)Download full-size image
Co-reporter:Lei Wang, Yongxiang Shi, Sixian Chen, Wencai Wang, Ming Tian, Nanying Ning, Liqun Zhang
Chemical Engineering Journal 2017 Volume 314(Volume 314) pp:
Publication Date(Web):15 April 2017
DOI:10.1016/j.cej.2016.12.015
•Aramid fibers were modified by catechol/polyamine deposition and EGDE grafting.•The deposition process of catechol/polyamine was accelerated by UV irradiation.•The modified aramid fibers show an improved interfacial adhesion property with rubber matrix.A facile and efficient mussel-like inspired modification method was developed to improve the interfacial adhesion of aramid fibers/rubber composites. The surfaces of aramid fibers were pre-deposited by poly(catechol/polyamine) (PCPA) layer, which was formed via the oxidation polymerization of catechol/polyamine (CPA) under UV irradiation. Then, the PCPA-coated fibers were further grafted with ethylene glycol diglycidyl ether (EGDE) to introduce epoxy groups onto aramid fibers surface. The kinetics of catechol oxidation was investigated by UV–vis measurements, suggesting that UV irradiation accelerated the polymerization process of CPA. The effects of EGDE concentration and grafting time on the adhesion force between aramid fibers and rubber matrix were evaluated by pull-out test, and a maximum increase of 85.6% in adhesion force was achieved, even better than that by dopamine in our previous study (a 67.5% improvement). Compared with the method based on dopamine chemistry, this method has advantages of lower cost (less than 1% of the price of dopamine) and shorter reaction time (3 h less in pre-deposition time). This study provides a new efficient strategy for fibers surface functionalization, which has promising application in rubber industry.Download high-res image (72KB)Download full-size image
Co-reporter:Mingzheng Hao, Miaomiao Tang, Wencai Wang, Ming Tian, Liqun Zhang, Yonglai Lu
Composites Part B: Engineering 2016 Volume 95() pp:395-403
Publication Date(Web):15 June 2016
DOI:10.1016/j.compositesb.2016.03.084
A novel procedure was demonstrated for the preparation of carbon nanotubes (CNTs) decorated with silver nanoparticles through poly(dopamine) (PDA) surface functionalization and ultraviolet (UV) irradiation. The CNT surfaces were first functionalized by a bio-inspired PDA layer. X-ray photoelectron spectroscopy (XPS) results showed that PDA layer with thicknesses in nanometers were formed on the outer surfaces of the CNTs. With the immersion of the PDA-coated CNTs (CNTs-PDA) into a silver plating bath, the silver ions attached to the CNTs-PDA surfaces were reduced in situ to silver nanoparticles by using the N-containing groups and reducing ability of PDA. The dense silver nanoparticles were further decorated on the CNTs-PDA surfaces under UV irradiation. High-resolution transmission electron microscopy (HRTEM) images showed that the spherical silver nanoparticles were about 3–4 nm in diameter and uniformly distributed on the outer surfaces of the CNTs. The distance between the nanoparticles was less than 10 nm. The as-prepared silver-decorated CNTs-PDA nanocomposites had excellent electrical conductivity, with a surface conductivity of up to 340 S/cm.
Co-reporter:Lei Wang, Yongxiang Shi, Rina Sa, Nanying Ning, Wencai WangMing Tian, Liqun Zhang
Industrial & Engineering Chemistry Research 2016 Volume 55(Issue 49) pp:
Publication Date(Web):November 16, 2016
DOI:10.1021/acs.iecr.6b03177
In this work, we develop a modified mussel-inspired method to enhance interfacial adhesion of aramid fiber to a rubber matrix. Through a simple dip-coating procedure, catechol and polyamine could initially codeposit as a poly(catechol-polyamine) (PCPA) coating on the surface of the aramid fiber. Then, the PCPA layer could be further grafted with silane coupling agent γ-(glycidyloxypropyltrimethoxysilane) (GPTMS). Results indicated that GPTMS was successfully grafted onto the aramid fiber surface via the bridging of the PCPA layer. The interfacial adhesion between the aramid fibers and the rubber matrix was improved compared to that achieved by polydopamine in our previous study. In addition, this method is more applicable to the rubber industry than polydopamine coating because of its cost-effectiveness and short reaction time.
Co-reporter:Ye Fu, Detao Zhao, Pengjun Yao, Wencai Wang, Liqun Zhang, and Yuri Lvov
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 15) pp:8156
Publication Date(Web):April 8, 2015
DOI:10.1021/acsami.5b00993
A novel aging-resistant styrene–butadiene rubber (SBR) composite is prepared using the antioxidant N-isopropyl-N′-phenyl-p-phenylenediamine (4010NA) loaded inside of halloysite clay nanotubes and used as filler. Loading the antioxidant inside of halloysite allows for its sustained release for nine months in the rubber matrix. By utilizing modified halloysite, the antioxidant concentration in this rubber nanoformulation is tripled without causing “blooming” defects. Furthermore, the halloysite is silanized to enhance its miscibility with rubber. The aging resistance of SBR–halloysite composites is studied by comparing the mechanical properties before and after thermal-oxidative aging. A seven-day test at 90 °C shows preservation of mechanical properties, and no 4010NA blooming is observed, even after one month. Styrene–butadiene rubber with 27 wt % halloysite loaded with 4010NA shows marked increase in aging resistance and promising future of halloysite as a functional rubber filler.Keywords: Aging resistant; elastomer; halloysite; nanotubes; sustained release;
Co-reporter:Rina Sa, Zhenhai Wei, Yan Yan, Lei Wang, Wencai Wang, Liqun Zhang, Nanying Ning, Ming Tian
Composites Science and Technology 2015 Volume 113() pp:54-62
Publication Date(Web):5 June 2015
DOI:10.1016/j.compscitech.2015.03.017
In this work, a combination of bio-inspired poly(dopamine) deposition and epoxy grafting was proposed, aiming at improving the surface activity and adhesion property of ultrahigh molecular weight polyethylene (UHMWPE) fibers. Inspired by adhesive proteins in mussels, dopamine self-polymerization was used to deposit a thin adherent poly(dopamine) (PDA) film onto the surface of UHMWPE fibers. Ethylene glycol diglycidyl ether (EGDE) was then grafted through the reactions with amide and imino groups of poly(dopamine) surface via a “two-step” or “one-step” method. The chemical structure and composition of fiber surface were characterized by XPS and ATR-IR. The surface hydrophilicity and wettability was determined by water contact angle (CA) measurement. SEM images revealed the morphology changes of the fibers. TGA and gravimetric method were applied for quantitative analysis of the surface treatment of each step. Epoxy value of modified fibers was evaluated by the titration method. The results confirmed that PDA was deposited and EGDE was successfully grafted onto the surface of fibers. The interfacial adhesion properties of UHMWPE fibers/rubber composites were investigated by single-fiber pull-out test, and 67.5% improvement was achieved. Resorcinol–formaldehyde–latex (RFL) dipping further enhanced the improvement to 365.4%. Catechol and epoxy grafted UHMWPE fabrics after dipping with RFL exhibited excellent adhesion properties with satisfying aging and fatigue resistance.
Co-reporter:Rina Sa, Yan Yan, Lei Wang, Yuan Li, Liqun Zhang, Nanying Ning, Wencai Wang and Ming Tian
RSC Advances 2015 vol. 5(Issue 114) pp:94351-94360
Publication Date(Web):27 Oct 2015
DOI:10.1039/C5RA19161K
In this research, ultraviolet (UV) irradiation induced graft polymerization of glycidyl methacrylate (GMA) was performed to modify the surface properties of poly-p-phenyleneterephthamide (PPTA) fibers. The improvement of adhesion with a rubber matrix was achieved due to the introduction of epoxy groups. The successful grafting of GMA on the PPTA fiber surface was ascertained by characterization using X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM). The tensile properties of PPTA fibers after each stage of surface modification were determined by tensile testing of single-filaments. A single-fiber pull-out test was applied to evaluate the adhesion of PPTA fibers with the rubber matrix. The pull-out force of grafted PPTA fibers exceeded that of the pristine fibers by 53.7%. Resorcinol–formaldehyde–latex (RFL) dipping was applied to further improve the adhesion properties. As a result, the fibers with GMA grafting followed by RFL dipping exhibited a 80.8% improvement compared with the pristine fibers and achieved much higher adhesion strength with rubber matrix, compared to the PPTA fibers modified with conventional industrial method of isocyanate (NCO) and RFL two bath dipping.
Co-reporter:Lu Wang, Linjia Hu, Shangbing Gao, Detao Zhao, Liqun Zhang and Wencai Wang
RSC Advances 2015 vol. 5(Issue 12) pp:9314-9324
Publication Date(Web):18 Dec 2014
DOI:10.1039/C4RA11904E
Polydopamine (PDA) is labeled as one category of synthetic melanin because it mimics the intriguing radical-scavenging behaviors of its natural counterpart. In this study, PDA modified montmorillonite (PDA-MMT) is utilized as a thermo-oxidative stabilizer for styrene butadiene rubber (SBR). PDA-MMT is fabricated by an aqueous dip-coating, based on the spontaneous alkaline auto-oxidative polymerization of dopamine hydrochloride in an air atmosphere, and is then associated with the SBR matrix via latex compounding. The PDA coating plays an excellent role as a radical-scavenger, and the uniformly dispersed PDA-MMT significantly functions as a physical barrier, which collaboratively work to reduce thermo-induced radical production during the decomposition process of SBR. This mechanism was attested by an in situ thermo-oxidative ageing test along with electron spin resonance (ESR) analysis. Thermal kinetics calculations showing that the apparent activation energy (Ea) of the SBR compounds is augmented by a large margin in the presence of PDA-MMT also corroborate this trend. Above all, the bio-inspired PDA-coating combined with the homogeneous dispersion of MMT exerts a synergistic effect on the thermo-oxidative stabilization of SBR matrix.
Co-reporter:Rina Sa, Yan Yan, Zhenhai Wei, Liqun Zhang, Wencai Wang, and Ming Tian
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 23) pp:21730
Publication Date(Web):November 17, 2014
DOI:10.1021/am507087p
A novel biomimetic surface modification method for meta-aramid (MPIA) fibers and the improvement on adhesion with rubber matrix was demonstrated. Inspired by the composition of adhesive proteins in mussels, we used dopamine (DOPA) self-polymerization to form thin, surface-adherent poly(dopamine) (PDA) films onto the surface of MPIA fibers simply by immersing MPIA fibers in a dopamine solution at room temperature. An epoxy functionalized silane (KH560) grafting was then carried out on the surface of the poly(dopamine)-coated MPIA, either by a “one-step” or “two-step” method, to introduce an epoxy group onto the MPIA fiber surface. The surface composition and microstructure of the modified MPIA was characterized by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results indicated successful grafting of KH560 on the PDA-coated MPIA surface. A single-fiber pull-out test was applied to evaluate the adhesion of MPIA fibers with the rubber matrix. Compared with the untreated MPIA fibers, the adhesion strength between the modified MPIA fibers by “one step” method with rubber matrix has an increase of 62.5%.Keywords: aramid fiber; aramid/rubber composite; dopamine; interfacial adhesion; silane; surface modification
Co-reporter:Ye Fu, Li Liu, Liqun Zhang, and Wencai Wang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 7) pp:5105
Publication Date(Web):March 20, 2014
DOI:10.1021/am5002663
Using tetraethyl orthosilicate as a main raw material, silica nanofibers (SiNFs) were prepared through the combination of a sol–gel process and an electrospinning technique followed by pyrolysis. Surface modified electrospun SiNFs developed by self-polymerization of polydopamine on the surface (SiNFs-PDA) served as templates for the electroless plating of silver nanoparticles (Ag NPs), using glucose as a reducing agent. The electrical resistivity of silver coated SiNPs-PDA (SiNFs-PDA/Ag) was measured by the four-point probe method and was found to be as low as 0.02 mΩ·cm at room temperature. The morphology of SiNFs-PDA/Ag before and after the blending with silicon rubber indicated a strong interaction between the silver layer and the SiNFs-PDA. The electrical and mechanical properties of the silicon rubber filled with SiNFs-PDA/Ag were studied to demonstrate the conductive performance application of SiNFs-PDA/Ag.Keywords: dopamine; electrical conductivity; electrospinning; silica; silver;
Co-reporter:Ye Fu;Guofeng Li;Ming Tian;Xing Wang;Liqun Zhang
Journal of Applied Polymer Science 2014 Volume 131( Issue 3) pp:
Publication Date(Web):
DOI:10.1002/app.39859
Surface modified fibrillar silicate (FS) was prepared by dopamine oxide polymerization and self-assembly of poly(dopamine) (PDA) on the FS surface, presynthesized silver nanoparticles subsequently adhered to the PDA functionalized FS (FS-PDA) surface by simply dipping FS-PDA in silver nanoparticles solution, owing to the metal-binding ability of catechol and nitrogen-containing groups on the PDA coating on the surface of FS. The chemical composition of the modified FS surface was determined by X-ray photoelectron spectroscopy. Surface morphological changes of the FS nanofibers were observed by transmission electron microscopy. The results indicated that the in situ spontaneous oxidative polymerization of dopamine on the FS surface and the immobilization of Ag nanoparticles on the surface of FS were successful. The FS-PDA/Ag demonstrated a significant enhancement in antibacterial properties compared to the pristine FS by using Escherichia coli as model strain. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39859.
Co-reporter:Qian Li, Ming Tian, Li Liu, Hua Zou, Liqun Zhang, Wen Cai Wang
Electrochimica Acta 2013 Volume 91() pp:114-121
Publication Date(Web):28 February 2013
DOI:10.1016/j.electacta.2012.12.137
A novel and facile strategy for the synthesis of α-Fe2O3@Ag hybrid nanoparticles with the assistance of dopamine surface functionalization was brought forward. The surface of the α-Fe2O3 particles was first functionalized by polydopamine (PDA), and silver was then plated on the α-Fe2O3/PDA surface by electroless plating. The method had the advantage of being simple, nontoxic, controllable, and cost-effective. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FTIR) were used to study the crystal structure, surface chemical compositions, and functional groups, respectively, of the hybrid nanoparticles. The results indicated that PDA was successfully deposited on the surfaces of α-Fe2O3 nanoparticles without affecting their crystal structures. The size and uniformity of the silver nanoparticles could be well controlled by adjusting the concentrations of silver nitrate (AgNO3) and polyvinylpyrrolidone (PVP). The morphology of the nanoparticles was observed by high-resolution transmission electron microscopy (HRTEM) and laser particle size and potential analyzer, respectively. The results showed that the silver nanoparticles were about 8 nm in diameter and uniformly coated on the surface of α-Fe2O3 nanoparticles. The silver nanoparticles showed good stability on the α-Fe2O3 substrate even after they were subjected to an ultrasonic experiment for 30 min.
Co-reporter:Wen Zhao, Lijun Zhu, Yonglai Lu, Liqun Zhang, Robert H. Schuster, Wencai Wang
Synthetic Metals 2013 Volume 169() pp:59-63
Publication Date(Web):1 April 2013
DOI:10.1016/j.synthmet.2013.03.004
•Magnetic CNTs were prepared by assembly of Fe3O4 nanoparticles to PDA-encapsulated CNTs.•PDA was formed by oxidative polymerization under an aerobic and alkaline condition.•PDA was used as an ionic sorbent to adsorb the cations.•Fe2O3 was used as seeds to induce the coprecipitation of Fe3O4.Magnetic carbon nanotube composites were prepared by decorating magnetic Fe3O4 nanoparticles on the external surface of polydopamine (PDA)-encapsulated carbon nanotubes (CNTs/PDA) in an in situ coprecipitation method. The process involved the encapsulation of CNTs with PDA, the deposition of Fe2O3 on the CNTs/PDA surface, and the deposition of Fe3O4 on the Fe2O3-deposited CNTs/PDA surface. In this process, PDA was used as an ionic sorbent to adsorb cations, and Fe2O3 was used as seeds to induce the coprecipitation of Fe3O4. The results show that the Fe2O3 and magnetic Fe3O4 nanoparticles are uniformly distributed on the surface of CNTs, and the magnetic CNT composites display good ferromagnetic property.
Co-reporter:Lijun Zhu, Yonglai Lu, Yiqing Wang, Liqun Zhang, Wencai Wang
Applied Surface Science 2012 Volume 258(Issue 14) pp:5387-5393
Publication Date(Web):1 May 2012
DOI:10.1016/j.apsusc.2012.02.016
Abstract
Inspired by the bio-adhesive proteins secreted by mussels for attachment to almost all wet substrates, a facile method involving oxidative polymerization of dopamine was proposed to prepare highly hydrophilic carbon black (CB) particles. A self-assembled polydopamine (PDA) ad-layer was formed via the oxidative polymerization of dopamine on the surface of CB simply by dipping the CB into an alkaline dopamine solution and mildly stirring at room temperature. The process is simple, controllable, and environment-friendly. The surface composition and structure of the CB were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The surface morphology of the CB was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the PDA ad-layer was successfully deposited on the CB surfaces. The PDA-functionalized CB (CB-PDA) gave a stable colloidal dispersion in water. Contact angle measurement results indicated that the hydrophilicity of CB was significantly improved after dopamine modification. TGA results confirmed that the modified CB maintained good heat resistance. The method provided a facile route to prepare hydrophilic CB having terminal hydroxyl groups.
Co-reporter:Fengdan Jiang;Liqun Zhang;Yi Jiang;Yonglai Lu
Journal of Applied Polymer Science 2012 Volume 126( Issue 3) pp:845-852
Publication Date(Web):
DOI:10.1002/app.36955
Abstract
The thermoplastic polyurethane/multiwalled carbon nanotube (TPU/CNT) nanocomposites with high conductivity and low percolation threshold value were prepared by melting blending and annealing treatment. The effect of annealing process on the microphase structure and the properties of TPU/CNT nanocomposites was studied. It has been shown that CNT flocculation can occur in TPU/CNT nanocomposites during the annealing process. At a critical CNT content, which defined the percolation threshold, CNTs could form conductivity network. The conductive percolation threshold value of TPU/CNT nanocomposites was decreased from 10 to 4% after annealing process, and the conductivity of TPU/CNT nanocomposites with 10 vol % of CNT could reach 1.1 S/m after an annealing time of 1 h. The significant enhancement of electrical conductivity was influenced by the annealing time and the content of CNTs. The formation of CNT networks was also verified by dynamic viscoelastic characterization. The results of X-ray diffraction and differential scanning calorimetry indicated that annealing process reinforced the microphase separation of the nanocomposites. Mechanical properties test showed that the annealing treatment was in favor of improving the mechanical properties; however, further increase in the annealing time has negative effect on the mechanical properties. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Yi Jiang;Yonglai Lu;Liqun Zhang;Li Liu;Yajie Dai
Journal of Nanoparticle Research 2012 Volume 14( Issue 6) pp:
Publication Date(Web):2012 June
DOI:10.1007/s11051-012-0938-x
Multi-walled carbon nanotubes (MWNTs) functionalized with poly(dopamine) (PDA) were found to cause the immobilization of silver nanoparticles on the surface. The PDA functional layer not only improved the dispersion of MWNTs in aqueous solution, but also was used as a platform for subsequent silver nanoparticle immobilization. The surface morphology of the functionalized MWNTs was observed by high-resolution transmission electron microscopy. The results showed that PDA layers with controlled thickness on the nanometer scale were formed on MWNT surfaces by in situ spontaneous oxidative polymerization of dopamine, and that high-density of homogeneously dispersed spherical silver nanoparticles with sizes of 3–4 nm were immobilized on their outer surface. The space between spherical silver nanoparticles is less than 10 nm. Both X-ray photoelectron spectroscopy and X-ray diffraction results showed that the Ag nanoparticles on the surface of hybrids exist in the zero valent state.
Co-reporter:C.Y. Li, W.C. Wang, F.J. Xu, L.Q. Zhang, W.T. Yang
Journal of Membrane Science 2011 Volume 367(1–2) pp:7-13
Publication Date(Web):1 February 2011
DOI:10.1016/j.memsci.2010.09.057
A facile method to immobilize the initiators onto the substrate is desirable for surface initiated atom transfer radical polymerization (ATRP). In this work, a two-step process was first developed for covalent immobilization of ATRP initiators on the outside and inside surfaces of the porous nylon membrane. The nylon membrane was functionalized with poly(dopamine), and the bromoalkyl initiators were then immobilized on the poly(dopamine) functionalized nylon membrane surfaces in a two-step solid-phase reaction, followed by ATRP of acrylic acid (AAc), which was deprotonated by the addition of NaOH in an aqueous solution. The resulting nylon membranes with grafted poly(acrylic acid) (PAAc) side chains were characterized by X-ray photoelectron spectroscopy (XPS). The morphology of the nylon membranes was studied by scanning electron microscopy (SEM). The results indicated that the grafted PAAc polymers formed uniformly inside the pores throughout the entire membrane. With the increase of the polymerizing time, the average diameter of the pores became smaller. A kinetics study revealed that the chain growth from the membranes was consistent with a “controlled” process. The nylon-g-PAAc membranes exhibit rapid and reversible responses of the flux to the environmental pH varied from 3 to 8. Between pH 3.5 and 5.5, the membranes demonstrated a pH-valve function as the carboxyl group changed from neutral to charged states with a corresponding variation of chain configuration.Graphical abstractResearch highlights▶ The bromoalkyl initiator was immobilized on the poly(dopamine) functionalized nylon membrane surface in a two-step solid-phase reaction. ▶ Acrylic acid (AAc), which was deprotonated by the addition of NaOH in a aqueous solution, was polymerized on the poly(dopamine) functionalized nylon membrane surface. ▶ The flux of aqueous solutions through the nylon-g-PAAc membranes exhibited a rapid and reversible response on the solution pH in the pH range of 3 to 8.
Co-reporter:Yi Jiang ;Wen-Cai Wang
Polymers for Advanced Technologies 2011 Volume 22( Issue 12) pp:2509-2516
Publication Date(Web):
DOI:10.1002/pat.1793
Abstract
PVDF/(PEI-C/PAA)n functional membranes were prepared by layer-by-layer (LbL) assembly, and their heavy metal ions adsorption capability was investigated. The changes in the chemical compositions of membrane surfaces were determined by X-ray photoelectron spectroscopy (XPS). XPS results show that the surface of the PVDF membrane can be alternatively functionalized by PEI-C and PAA. The membrane surface hydrophilicity was evaluated through water contact angle measurement. Contact angle results show that the surface hydrophilicity of the membrane surface depends on the outermost deposited layer. Morphological changes of membrane surfaces were observed by scanning electron microscopy (SEM). The water fluxes for these membranes were elevated after modification. The performances of the PVDF/(PEI-C/PAA)n membranes on the adsorption of copper ions (Cu2+) from aqueous solutions were investigated by inductively coupled plasma (ICP). The results indicate that the PVDF/(PEI-C/PAA)n functional membranes show high copper ions adsorption ability. Copyright © 2010 John Wiley & Sons, Ltd.
Co-reporter:Wencai Wang, Xiaodong Tian, Yiping Feng, Bing Cao, Wantai Yang and Liqun Zhang
Industrial & Engineering Chemistry Research 2010 Volume 49(Issue 4) pp:1684-1690
Publication Date(Web):December 30, 2009
DOI:10.1021/ie9008666
Pore-filling N-isopropylacrylamide (NIPAAM) polymer hydrogels were successfully grafted onto track-etched polycarbonate (PC) membranes by plasma-induced graft copolymerization. The microstructure and morphology of the PC-g-PNIPAAM membranes were investigated by XPS, SEM, ATR-FTIR, TGA, and water flux experiments. The effective pore sizes were regulated by the volume change of the cross-linked PNIPAAM hydrogels in the temperature range around its lower critical solution temperature (LCST). The PC-g-PNIPAAM membranes demonstrated a fast and reversible valve switching mechanism in a small temperature range. The on−off water flux ratio became more significant with the increase of the monomer concentration. Contact angle results showed that the thermal-responsive gating characteristics of PC-g-PNIPAAM membranes were mainly dependent on the pore size change.
Co-reporter:Yuan Liao, Yaqin Wang, Xiaoxia Feng, Wencai Wang, Fujian Xu, Liqun Zhang
Materials Chemistry and Physics 2010 Volume 121(Issue 3) pp:534-540
Publication Date(Web):1 June 2010
DOI:10.1016/j.matchemphys.2010.02.019
Immobilization of silver nanoparticles on the dopamine functionalized polyimide (PI) films was carried out by photo-induced silver ion-reduction under atmosphere conditions. The dopamine has been successfully deposited on the PI surface in mild aqueous environments. The effects of pH, dopamine concentration and reaction time on the dopamine polymerization were investigated. The water contact angles of the poly(dopamine) functionalized PI films reduced remarkably in comparison with that of the pristine PI film. The chemical composition and structure of the UV-induced deposited-silver on the modified PI films were characterized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The topography of the modified PI films was investigated by scanning electron microscope (SEM). The deposited poly(dopamine) layer acted as binding sites for the silver ions. The silver-plated PI films showed good antibacterial activity due to that biofilm formation was inhibited on the polymeric surfaces in contact with bacteria.
Co-reporter:Chunyan Li;Bing Cao;Qifang Li;Jing Zhao ;Liqun Zhang
Polymers for Advanced Technologies 2010 Volume 21( Issue 10) pp:698-703
Publication Date(Web):
DOI:10.1002/pat.1485
Abstract
Surface functionalization of the plasma-pretreated polycarbonate (PC) track-etched membranes via plasma-induced thermally graft copolymerization of acrylic acid (AAc) was carried out. The resulting PC membranes with grafted AAc side chains were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric (TG) analysis. The morphology of the PC membranes was studied by scanning electron microscopy (SEM). The results showed that the grafted PAAc polymers were formed uniformly inside the pores throughout the entire membrane thickness. With increase in the pore-filling ratio, the pore diameters of PAAc-grafted membranes became smaller. The PC-g-PAAc membranes exhibit rapid and reversible response of the flux to the environmental pH as pH is switched between 3 and 9. Between pH 3.5 and 5.5, the membranes demonstrate a pH-valve function as the carboxyl group changes from neutral to charged with a corresponding variation in chain configuration. Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:Weisong Cui, Dezhen Wu, Wen-Cai Wang, Liqun Zhang, Bing Cao, Riguang Jin
Surface and Coatings Technology 2009 203(13) pp: 1885-1890
Publication Date(Web):
DOI:10.1016/j.surfcoat.2009.01.018
Co-reporter:Dezhen Wu;Tao Zhang;Wen-Cai Wang;Liqun Zhang;Riguang Jin
Polymers for Advanced Technologies 2008 Volume 19( Issue 5) pp:335-341
Publication Date(Web):
DOI:10.1002/pat.1007
Abstract
Argon plasma-pretreated polyimide (PI) films were subjected to UV-induced surface graft copolymerization with 4-vinylpyridine(4VP) under atmospheric conditions. Electroless plating of silver was carried out effectively on the 4VP graft copolymerized PI (PI-g-P4VP) surface after PdCl2 activation and in the absence of SnCl2 sensitization (the Sn-free process). The surface compositions of the modified PI films were studied by X-ray photoelectron spectroscopy (XPS). XPS results showed that the PI-g-P4VP surface is ready for electroless deposition of silver via the Sn-free process. The grafted 4VP layer with well-preserved pyridine groups was used not only as the chemisorption sites for the palladium complexes (without the need for prior sensitization by SnCl2) during the electroless plating of silver, but also as an adhesion promotion layer for the electrolessly deposited silver. The silver metallized PI films show high reflectivity and conductivity with a surface resistance of 1.5 Ω and a reflectivity of 91.3%, respectively. Copyright © 2007 John Wiley & Sons, Ltd.
Co-reporter:Wen-Cai Wang;Koon-Gee Neoh;En-Tang Kang
Macromolecular Rapid Communications 2006 Volume 27(Issue 19) pp:1665-1669
Publication Date(Web):27 SEP 2006
DOI:10.1002/marc.200600409
Summary: Surface functionalization of Fe3O4 magnetic nanoparticles (MNP) via living radical graft polymerization with styrene and acrylic acid (AAc) in the reversible addition-fragmentation chain transfer (RAFT)-mediated process was reported. Peroxides and hydroperoxides generated on the surface of Fe3O4 nanoparticles via ozone pretreatment facilitated the thermally initiated graft polymerization in the RAFT-mediated process. A comparison of the MNP before and after the RAFT-mediated process was carried out using transmission electron microscopy (TEM) analysis, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). Gel permeation chromatography (GPC) was used to determine the molecular weight of the free homopolymer in the reaction mixture. Well-defined polymer chains were grown from the MNP surfaces to yield particles with a Fe3O4 core and a polymer outer layer. The resulting core–shell Fe3O4-g-polystyrene and Fe3O4-g-poly(acrylic acid) (PAAc) nanoparticles formed stable dispersions in the organic solvents for polystyrene (PS) and PAAc, respectively.
![Poly[(5,7-dihydro-1,3,5,7-tetraoxobenzo[1,2-c:4,5-c']dipyrrole-2,6(1H,3H)-diyl)-1,4-phenyleneoxy-1,4-phenylene]](http://img.cochemist.com/ccimg/25100/25036-53-7.png)
![Poly[(5,7-dihydro-1,3,5,7-tetraoxobenzo[1,2-c:4,5-c']dipyrrole-2,6(1H,3H)-diyl)-1,4-phenyleneoxy-1,4-phenylene]](http://img.cochemist.com/ccimg/25100/25036-53-7_b.png)
