Co-reporter:Yu Shao;Guang-Zhong Yin;Xiangkui Ren;Xinlin Zhang;Jing Wang;Kai Guo;Xiaopeng Li;Chrys Wesdemiotis;Wen-Bin Zhang;Shuguang Yang;Bin Sun
RSC Advances (2011-Present) 2017 vol. 7(Issue 11) pp:6530-6537
Publication Date(Web):2017/01/18
DOI:10.1039/C6RA28147H
This article reports the enhanced photoluminescent properties observed in the crystals of a cube-plane-cube shape amphiphile composed of perylene diimide (PDI) tethered with polyhedral oligomeric silsesquioxanes (POSS) at the imide position via either rigid or flexible linkages (POSS-PDI-POSS). The fluorescence quantum yields (Φf) of the conjugates in crystal (∼0.48) are much higher than that of the more amorphous samples (∼0.17) and that of the reference compound without pendant POSS cage (∼0.12). The enhancement was understood in three ways. First, their self-assembly behaviors in gaseous phase were studied by tandem mass spectrometry coupled with traveling wave ion mobility separation; second, their self-assembly behaviors in solution were revealed by concentration- and solvent-dependent experiments using UV/vis absorption and fluorescence spectrometry; and third, the molecular packing in crystals was determined by wide angle X-ray diffraction and transmission electron microscope. The results demonstrate the conjugates' strong tendency toward dimer formation in solution and show a unique molecular packing of discrete dimeric motifs in the solid states. It suggests that the high Φf of these conjugates can be attributed to the discontinuous π–π stacking, which results in a weaker electron interaction between the dimers, and the relatively fixed position of the PDI, which prohibits the common structural relaxation of PDIs π-planes.
Co-reporter:Yu Shao;Xinlin Zhang;Kai Liang;Jing Wang;Yuejian Lin;Shuguang Yang;Wen-Bin Zhang;Bin Sun
RSC Advances (2011-Present) 2017 vol. 7(Issue 26) pp:16155-16162
Publication Date(Web):2017/03/09
DOI:10.1039/C7RA00779E
This article reports a comparative study on the synthesis, self-assembly, and photophysical properties of perylene diimides (PDIs) symmetrically tethered with long alkyl chains or polyhedral oligomeric silsesquioxanes (POSS) at the imide position and/or bromo substitutions at 1,7-positions of the bay area. This series of samples include dodecyl–PDIH–dodecyl (1), dodecyl–PDIBr–dodecyl (2), POSS–PDIH–POSS (3), and POSS–PDIBr–POSS (4). In solution, the PDIs with bromine substitution at bay area (2, 4) exhibit red-shifted absorption maximum compared to those without (1, 3), which is consistent with a twisted perylene chromophore as revealed by molecular simulation. Similar bathochromatic shift was observed on the solid crystal state emission of 2 as compared to 1. However, in crystals, the emission spectrum of 4 exhibits a seemingly hypochromatic shift relative to that of 3, which could be rationalized by their packing in the crystals. The bromo substitution is believed to partially quench the fluorescence and the relatively loose packing of the twisted π-plane of 4 may not be able to confine π-plane in place, leaving multiple pathways for fluorescent quenching rather than red-shifted emission. While both 3 and 4 exhibit a unique dimer packing scheme, the dimers have quite different longitudinal offset and transverse offset of the π-plane. The longitudinal offset in dimers of 4 is so large that the naphthalene moieties in the dimer almost adopt a face-to-face arrangement and their mutual interactions are considered relatively independent. All these contribute to the less red-shifted fluorescent emission and the lower fluorescent yields in crystals of 4 relative to 3 as compared to that in solution. The study shall shed light into the complicated mutual interactions among intrinsic electronic structure, microscopic molecular packing, and the macroscopic optoelectronic properties.
Co-reporter:Xin Wang;Ting Zeng;Mohamed Nourrein;Bo-Han Lai;Kaiwen Shen;Chien-Lung Wang;Bin Sun
RSC Advances (2011-Present) 2017 vol. 7(Issue 42) pp:26074-26081
Publication Date(Web):2017/05/15
DOI:10.1039/C7RA04296E
In this work, an amphiphilic perylene diimide (1,7-TEG-PDI-C12) that bears two hydrophilic triethylene glycol (TEG) chains at its bay position, and two hydrophobic dodecyl chains at its imide position was synthesized to identify the roles of concentration and H-bonding on the self-assembly morphology of the amphiphilic PDI. Since 1,7-TEG-PDI-C12 was prepared from the reaction of two bifunctional reactants, TEG and N,N′-bis(n-dodecyl)-1,7-dibromo-perylene-3,4:9,10-tetracarboxylic diimide, careful choices of solvent, base, and the stoichiometry of crown ether and base were found to be critical in reaching high reaction yield under mild conditions. TEM and SEM results revealed the abundant concentration-dependent self-assembly morphologies of 1,7-TEG-PDI-C12. Characterization results including UV-vis, fluorescence, NMR, IR and XRD analysis show that the formation of the self-assembled structure is a synergetic result of the intermolecular π–π interaction and H-bonding of 1,7-TEG-PDI-C12.
Co-reporter:Weili Li;Wei Yao;Jun Wang;Zhenyu Qiu;Jijun Tang;Shengyuan Yang;Zexiao Xu;Rong Hu;Anjun Qin;Ben Zhong Tang
RSC Advances (2011-Present) 2017 vol. 7(Issue 65) pp:41127-41135
Publication Date(Web):2017/08/18
DOI:10.1039/C7RA06527B
For polymer materials, both their compositions and preparation process greatly influence their service performance. Thus, the sound understanding of the relationship between materials' preparation processes and their properties is paramount. However, current research methods are partially limited due to the absence of a direct testing method to track the entire process, e.g. synthesizing, curing, ageing, and so on. With the ability for real-time sensitive characterization, fluorescence spectroscopy may be applied in testing polymer materials' performance. Here, we synthesized a novel aggregation induced emission (AIE) resin named TPE–EPOXY resin and prepared an AIE coating based on it. According to restriction of intramolecular rotation (RIR) mechanism, the preparation, curing, and aging processes for the AIE polymer resins & coatings could be studied with real-time observation. In addition, their properties could also be studied systematically. The results in this paper pave a good way to understand the relationship between the internal structure and the properties of polymer materials. Moreover, the prepared AIE polymer resins has a potential to expand the application fields of the AIE mechanism.
Co-reporter:Xiaohuan Ji;Franziska Griesing;Ruijia Yan;Bin Sun;Werner Pauer;Yushan Sun;Hans-Ulrich Moritz
RSC Advances (2011-Present) 2017 vol. 7(Issue 79) pp:50176-50187
Publication Date(Web):2017/10/26
DOI:10.1039/C7RA10111B
A series of poly(styrene-co-divinylbenzene)/silver nanoparticle (P(St-DVB)/AgNP) composite microspheres with tunable porosity were synthesized by seed swelling polymerization in one pot using linear polystyrene seeds as templates and nanosized organic soluble AgNPs as the silver source. The polymerization of styrene and divinylbenzene took place inside the seed particles and AgNPs were dispersed directly into the mixture of styrene and divinylbenzene during the polymerization. The morphology properties of P(St-DVB)/AgNPs microspheres were characterized by optical microscope, scanning electron microscope (SEM) and nitrogen adsorption/desorption. The influencing parameters on the morphology of the microspheres, including feed ratio of styrene (monomer) and divinylbenzene (crosslinker), addictive amount of AgNPs and the variety of the porogens were systematically investigated. The porosity of the composite microspheres could be tuned from nonporous to mesoporous and to macroporous by control over these parameters. Meanwhile, AgNPs loading dispersity of the composite microspheres was characterized by transmission electron microscope (TEM), energy-dispersive X-ray spectroscopy (EDS), SEM and thermogravimetric analysis (TGA). TEM, EDS and SEM results demonstrated that the AgNPs had been loaded both inside and on the surface of the microspheres. The sizes of the loaded AgNPs were influenced by the addictive amount of AgNPs and the kinds of porogens used in the polymerization. Moreover, compared to the P(St-DVB) microspheres, the Ag-loading composite microspheres synthesized in this paper exhibited excellent catalytic activity and reusability in the degradation of methylene blue in the presence of NaBH4.
Co-reporter:Jianyong Feng;Deteng Zhang;Changyou Gao
Journal of Materials Chemistry B 2017 vol. 5(Issue 26) pp:5176-5188
Publication Date(Web):2017/07/04
DOI:10.1039/C7TB00601B
Aligned fiber scaffolds can mimic the parallel aligned fibrils in the extracellular matrix (ECM) of bones, and thus regulate many cellular behaviors. The aligned scaffolds are usually prepared by a microplate micropatterned method, freeze casting, evaporation, slip casting, ice-templating, plain weaving, and fiber forming techniques. In this study, the melt spinning technology, which has the advantages of a higher spinning speed, solvent-free processing and readily scalable production, was used to prepare poly(L-lactide) (PLLA) melt spun fibers with an average diameter of 70.3 ± 11.4 μm. The fibers were further bonded by 5% PLLA tetrahydrofuran solution to prepare PLLA spun fiber-aligned scaffolds. Collagen and chitosan molecules were coated onto the fibers/into the scaffolds to obtain multiple biochemical and surface aligned topography cues, respectively. The collagen or chitosan-coated PLLA aligned scaffolds could effectively improve the viability, adhesion, length and migration behaviors of osteoblasts in vitro. In particular, the collagen coated aligned scaffold had the largest cell length and the fastest migration rate, with a preferential direction along the fibers. This type of scaffold provides a versatile substrate to control cell behaviors, having great potential for bone regeneration.
Co-reporter:Yanhua Cheng;Gen Chen;Haobin Wu;Yunfeng Lu
Journal of Materials Chemistry A 2017 vol. 5(Issue 27) pp:13944-13949
Publication Date(Web):2017/07/11
DOI:10.1039/C7TA03043F
Building nanocomposite architectures based on carbon nanotubes (CNTs) and active nanoparticles (NPs) with an engineered interface is of great interest for developing the ability to store electrochemical energy. The use of cellulose to direct hetero-assembly was achieved by in situ regenerating an ionic liquid mixture (CNTs, NPs, cellulose) in water, and was applied to the fabrication of flexible anodes consisting of CNTs and NPs. These anodes showed CNTs threading through their structures and exhibited strong interfacial contacts, which provided a relatively short lithium-ion diffusion length and continuous electron conduction pathway as well as high mechanical stability. When evaluated as an anode material for a lithium-ion battery, the flexible nanocomposites showed high reversible capacity and good rate performance compared to traditionally made electrodes, demonstrating a simple and green strategy for the industrial-scale production of energy-storage devices.
Co-reporter:Zhouqi Meng;Fang Wei;Ronghua Wang;Mengge Xia;Zhigang Chen;Huiping Wang
Advanced Materials 2016 Volume 28( Issue 2) pp:245-253
Publication Date(Web):
DOI:10.1002/adma.201502669
Co-reporter:Yanhua Cheng;Zheng Chen;Haobin Wu;Yunfeng Lu
Advanced Functional Materials 2016 Volume 26( Issue 9) pp:1338-1346
Publication Date(Web):
DOI:10.1002/adfm.201504134
Building nanocomposite architectures based on nanocarbon materials (such as carbon nanotubes and graphene nanosheets) and metal-oxide nanoparticles is of great interests for electrochemical energy storage. Here, an ionic-liquid-assisted strategy is presented to mediate the in situ growth of TiO2 nanocrystals with controlled size on carbon nanotubes and graphene, and also reduce the modified carbon supports to recover the graphitic structure simultaneously. The as-prepared nanocomposites exhibit a highly porous and robust structure with intimate coupling between TiO2 nanocrystals and carbon supports, which offers facile ion and electron transport pathway as well as high mechanical stability. When evaluated as electrode materials for lithium-ion batteries, the nanocomposites manifest high specific capacity, long cycling lifetime, and excellent rate capability, showing their promising application in high-performance energy storage devices.
Co-reporter:Yanhua Cheng;Zheng Chen;Yunfeng Lu
Advanced Energy Materials 2015 Volume 5( Issue 6) pp:
Publication Date(Web):
DOI:10.1002/aenm.201401207
Co-reporter:Wenju Xu, Zhouqi Meng, Nuo Yu, Zhigang Chen, Bin Sun, Xiaoze Jiang and Meifang Zhu
RSC Advances 2015 vol. 5(Issue 10) pp:7074-7082
Publication Date(Web):15 Dec 2014
DOI:10.1039/C4RA15524F
WO3−x nanomaterials have been demonstrated to be one kind of efficient near-infrared (NIR) laser-driven photothermal nanoagents, but their photothermal stability is still unsatisfied. In addition, a 980 nm laser is usually used as NIR light source, but it has an overheating effect due to optical absorption of water and biological specimens. To address these problems, we have prepared PEGylated Cs-doped WO3 (CsxWO3) nanorods by a solvothermal synthesis—PEGylation two-step route. CsxWO3 nanorods have diameters of ∼11 nm and lengths of ∼50 nm, and they exhibit increased absorption in the NIR region (700–1100 nm). With PEGylated CsxWO3 nanorods as the photothermal nanoagent, we compare the overheating and penetration effects of 915 and 980 nm lasers as NIR light sources. Compared with the 980 nm laser, the 915 nm laser provides drastically less overheating of water, and higher penetration ability of water/skin due to quite low water absorption. Importantly, under the irradiation of a 915 nm laser, CsxWO3 nanorods exhibit excellent photothermal conversion performance with high stability. Furthermore, by the photothermal effect of PEGylated CsxWO3 nanorods, in vivo cancer cells can be efficiently destroyed under the irradiation of a 915 nm laser. Therefore, PEGylated CsxWO3 nanorods can be used as a promising efficient and stable NIR-laser-driven photothermal agent against in vivo cancer cells.
Co-reporter:Wenju Xu, Qiyun Tian, Zhigang Chen, Mengge Xia, Daniel K. Macharia, Bin Sun, Ling Tian, Yifei Wang and Meifang Zhu
Journal of Materials Chemistry A 2014 vol. 2(Issue 34) pp:5594-5601
Publication Date(Web):25 Jun 2014
DOI:10.1039/C4TB00669K
Near-infrared (NIR) laser-induced photothermal ablation (PTA) therapy has great potential to revolutionize conventional therapeutic approaches for cancers, and a prerequisite is to obtain biocompatible and efficient photothermal agents. Herein, we have developed hydrophilic W18O49 nanowires with average lengths of about 800 nm (abbreviated as W18O49-800 NWs) as an efficient photothermal agent, which are prepared by the solvothermal synthesis—simultaneous PEGylation/exfoliation/breaking two-step route. These W18O49-800 NWs exhibit stronger NIR photoabsorption than short nanowires with average lengths of about 50 nm (abbreviated as W18O49-50 NWs) that are prepared via a solvothermal one-step route. Under irradiation of 980 nm with a safe intensity of 0.72 W cm−2, the aqueous dispersion of W18O49-800 NWs (1.0 mg mL−1) exhibits the temperature elevation by 35.2 °C in 5 min; which is a 37.5% increase compared to that (by 25.6 °C) from W18O49-50 NWs (1.0 mg mL−1). More importantly, under 980 nm laser irradiation (0.72 W cm−2) for 10 min, in vivo cancer cells can be efficiently ablated by the photothermal effects of W18O49-800 NWs. Therefore, these W18O49-800 NWs can be used as a more efficient and promising photothermal nanoagent for the ablation of cancer cells in vivo.
Co-reporter:Xiong Li, Ce Wang, Yin Yang, Xuefen Wang, Meifang Zhu, and Benjamin S. Hsiao
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 4) pp:2423
Publication Date(Web):January 27, 2014
DOI:10.1021/am4048128
A new type of dual-biomimetic hierarchically rough polystyrene (PS) superhydrophobic micro/nano-fibrous membrane was fabricated via a one-step electrospinning technique at various polymer concentrations from 15 to 30 wt %. The obtained micro/nano-fibers exhibited a nanopapillose, nanoporous, and microgrooved surface morphology that originated from mimicking the micro/nanoscale hierarchical structures of lotus leaf and silver ragwort leaf, respectively. Superhydrophobicity and high porosity of such resultant electrospun nanofibrous membranes make them attractive candidates for membrane distillation (MD) application with low energy water recovery. In this study, two kinds of optimized PS nanofibrous membranes with different thicknesses were applied for desalination via direct contact MD. The membranes maintained a high and stable permeate water vapor flux (104.8 ± 4.9 kg/m2·h, 20 g/L NaCl salt feed for a thinner PS nanofibrous membrane with thickness of 60 μm; 51 ± 4.5 kg/m2·h, 35 g/L NaCl salt feed for the thicker sample with thickness of 120 μm; ΔT = 50 °C) for a test period of 10 h without remarkable membrane pores wetting detected. These results were better than those of typical commercial polyvinylidene fluoride (PVDF) MD membranes or related PVDF nanofibrous membranes reported in literature, suggesting excellent competency of PS nanofibrous membranes for MD applications.Keywords: membrane distillation; nanofibrous membrane; polystyrene; superhydrophobic;
Co-reporter:Hao You, Xiong Li, Yin Yang, Baoyi Wang, Zhuoxi Li, Xuefen Wang, Meifang Zhu, Benjamin S. Hsiao
Separation and Purification Technology 2013 Volume 108() pp:143-151
Publication Date(Web):19 April 2013
DOI:10.1016/j.seppur.2013.02.014
In this study, a new class of high performance thin film nanocomposite (TFNC) ultrafiltration membrane based on a polyacrylonitrile (PAN) nanofibrous substrate coupled with a thin hydrophilic nanocomposite barrier layer was fabricated by electrospinning technique combined with solution treatment method, and was used as an ultrafiltration media to separate an oil/water emulsion. The hydrophilic nanocomposite barrier layer was composed of crosslinked poly(vinyl alcohol) (PVA) thin layer incorporating surface oxidized multi-walled carbon nanotubes (MWNTs), and was prepared by immersing electrospun PVA–MWNT/PAN nanofibrous double-layer mats into optimized water/acetone solution and then chemically crosslinked by glutaraldehyde in water/acetone solution. The electrospun PVA–MWNT nanofiber top layer would be swollen to merge imperceptibly into an integrated barrier film on the supporting PAN layer. The variation of the free volume of PVA barrier layer with different MWNTs contents was investigated by positron annihilation lifetime spectroscopy (PALS). The PALS results proved that the free volume of PVA–MWNT/PAN TFNC membranes increased markedly with the increase of MWNTs concentration in the PVA layer, and the filtration evaluation also confirmed that the incorporation of MWNTs into PVA barrier layer could improve the water flux significantly, which indicated that more effective water channels were generated in the nanocomposite barrier layer by the incorporation of MWNTs into PVA barrier layer. The PVA–MWNT/PAN TFNC (10 wt.% MWNT) membrane showed very high water flux (270.1 l/m2 h) with high rejection rate (99.5%) even at very low feeding pressure (0.1 MPa). In addition, the PVA–MWNT/PAN composite membranes showed very good overall mechanical properties.Highlights► High flux low pressure thin film nanocomposite filtration membranes were prepared. ► PVA–MWNT/PAN nanofibrous double layer mats were prepared by electrospinning. ► Electrospun PVA–MWNT top layer was solution treated to an integrated barrier film. ► The free volume characteristics of the PVA–MWNT barrier layers were studied. ► Filtration performances of the PVA–MWNT/PAN nanocomposite membranes were evaluated.
Co-reporter:Zongyuan Liu, Xiong Li, Yin Yang, Kai Zhang, Xuefen Wang, Meifang Zhu, Benjamin S. Hsiao
Polymer 2013 Volume 54(Issue 21) pp:6045-6051
Publication Date(Web):4 October 2013
DOI:10.1016/j.polymer.2013.08.051
In this work, poly(l-lactic acid) (PLLA) ultrafine fibers with different morphology and structure were fabricated by a novel linear-jet electrospinning method which relies on a conventional electrospinning set-up with continuous rotating drum. To control the morphology and structure of PLLA electrospun fibers, different solution systems and electrospinning conditions were investigated. Two PLLA solution systems (PLLA/DMF/CH2Cl2 and PLLA/CH2Cl2) with different concentration and conductivity were used for the electrospinning and their influences on the formation of the linear electrospinning jet were discussed. Two types of collecting patterns with aligned buckling and linear structure were achieved under the linear electrospinning jet. Highly aligned PLLA electrospun fibers with porous surface could be formed by using the highly volatile solvent CH2Cl2. Here, it should be emphasized that the diameter and surface porosity of such highly aligned PLLA electrospun fibers can be fine tuned by varying the winding velocity. The results of SEM images and polarized FTIR investigations verified that the as-spun PLLA porous surface fibers were highly aligned and molecularly oriented, leading to the enhanced mechanical performance as compared to the non-woven PLLA electrospun fibers.
Co-reporter:Yan Zhang, Boon M. Teo, Almar Postma, Francesca Ercole, Ryosuke Ogaki, Meifang Zhu, and Brigitte Städler
The Journal of Physical Chemistry B 2013 Volume 117(Issue 36) pp:10504-10512
Publication Date(Web):August 15, 2013
DOI:10.1021/jp407106z
Mixed one-step poly(dopamine) (PDA)/highly branched poly(N-isopropylacrylamide) (pNiPAAm) coatings have been assembled and characterized by X-ray photoelectron spectroscopy (XPS), UV–vis spectroscopy, atomic force microscopy, and quartz crystal microbalance with dissipation monitoring (QCM-D) depending on the deposition temperature below and above the lower critical solution temperature (LCST) of the pNiPAAm. Mixed films were confirmed. The protein adsorption at 24 °C was found to be reduced with increasing amount of pNiPAAm in the mixed coatings, while there was no difference observed for proteins deposition at 39 °C. Further, the ability of these mixed coatings in comparison to the pure PDA and pNiPAAm films to serve as capping layer for surface-immobilized zwitterionic or positively charged liposomes has been assessed by QCM-D. The adhesion of hepatocytes, macrophages, and myoblast to these liposomes-containing hybrid coatings and the uptake of fluorescent lipids from the surface by the adhering cells depending on the capping layers were compared. The latter aspect was found to be dependent on the used capping layer and the type of liposome as carrier for the fluorescent lipid, with the highest uptake found for positive liposomes and pure pNiPAAm as capping layer. Taken together, the assembled hybrid coatings have the potential to be used as functional coatings toward surface-mediated drug delivery.
Co-reporter:Yan Zhang, Karthiga Panneerselvam, Ryosuke Ogaki, Leticia Hosta-Rigau, Rebecca van der Westen, Bettina E. B. Jensen, Boon M. Teo, Meifang Zhu, and Brigitte Städler
Langmuir 2013 Volume 29(Issue 32) pp:10213-10222
Publication Date(Web):July 15, 2013
DOI:10.1021/la402118u
Many biomedical applications benefit from responsive polymer coatings. The properties of poly(dopamine) (PDA) films can be affected by codepositing dopamine (DA) with the temperature-responsive polymer poly(N-isopropylacrylamide) (pNiPAAm). We characterize the film assembly at 24 and 39 °C using DA and aminated or carboxylated pNiPAAm by a quartz crystal microbalance with dissipation monitoring (QCM-D), X-ray photoelectron spectroscopy, UV–vis, ellipsometry, and atomic force microscopy. It was found that pNiPAAm with both types of end groups are incorporated into the films. We then identified a temperature-dependent adsorption behavior of proteins and liposomes to these PDA and pNiPAAm containing coatings by QCM-D and optical microscopy. Finally, a difference in myoblast cell response was found when these cells were allowed to adhere to these coatings. Taken together, these fundamental findings considerably broaden the potential biomedical applications of PDA films due to the added temperature responsiveness.
Co-reporter:Yingying Pan, Fengwei Liu, Dan Xu, Xiaoze Jiang, Hao Yu, Meifang Zhu
Progress in Natural Science: Materials International 2013 Volume 23(Issue 1) pp:89-93
Publication Date(Web):February 2013
DOI:10.1016/j.pnsc.2013.01.016
A kind of novel acrylic resin denture base enhanced by PMMA-modified hydroxyapatite (M-HAP) was prepared and the modification effect of HAP on the mechanical properties of denture base material was investigated in the present study. HAP whiskers were prepared by hydrothermal homogeneous precipitation process and were silanized by the coupling agent, 3-methacryloxy propyl trimethoxyl silane (γ-MPS), to induce the vinyl groups onto its surface. Methyl methacrylate (MMA) were then modified outside the vinyl functionalized HAP via polymerization to build a similar chemical structure with the acrylic matrix. A novel acrylic resin denture base was obtained through self-curing process with the incorporation of this PMMA-modified HAP, and the content of which ranged from 0 wt% to 0.8 wt%. Thermal gravimetric analysis (TGA), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and universal testing apparatus were used to characterize M-HAP and corresponding denture base. The results showed that PMMA were successfully grafted onto the surface of HAP whiskers with up to 15 wt% and the modification turned out to be useful for the dispersion and compatibility of whiskers in the acrylic resin matrix. The mechanical properties of the prepared denture base samples were enhanced greatly after incorporating with M-HAP fillers. The optimal incorporated content of M-HAP was also investigated.
Co-reporter:Hao You, Yin Yang, Xiong Li, Kai Zhang, Xuefen Wang, Meifang Zhu, Benjamin S. Hsiao
Journal of Membrane Science 2012 Volumes 394–395() pp:241-247
Publication Date(Web):15 March 2012
DOI:10.1016/j.memsci.2011.12.047
In this study, high flux thin film nanofibrous composite (TFNC) membrane consisting of a nonwoven nanofibrous supporting layer and a thin hydrophilic barrier layer was developed and used as an ultrafiltration media to separate an oil/water emulsion at low feeding pressure. Firstly, the hydrophilic barrier layer was fabricated by electrospraying polyvinyl alcohol (PVA) on nanofibrous polyacrylonitrile (PAN) substrate. Secondly, the deposited PVA top layer was swollen to merge imperceptibly into an integrated barrier film on the supporting layer by immersing PVA/PAN double-layer membranes into suitable solvent water and nonsolvent acetone mixture, and then chemically crosslinked by glutaraldehyde in water/acetone solution. The water content of water/acetone solution and the immersion time were optimized to achieve the integrated and nonporous PVA barrier layer. Filtration performance of the resulting PVA/PAN TFNC membranes was evaluated by the oil/water emulsions separation system. Results showed that the optimized TFNC membrane possessed high flux (347.8 l/m2 h) with high rejection rate (99.6%) at very low feeding pressure (0.2 MPa). It is believed that the strategy for fabricating TFNC membranes described here can be extended easily to fabricate TFNC membranes from many other polymeric membrane materials simply by choosing the suitable solution system for post-treatment.Highlights► Beaded PVA layer was fabricated via electrospraying on nanofibrous PAN substrate. ► The solution treatment bath was composed of water and acetone. ► Electrosprayed PVA top layer was swollen to an integrated barrier film. ► Ultrafiltration performances of the PVA/PAN composite membranes were evaluated.
Co-reporter:Miao-miao Yu, Shao-hua Chen, Zhe Zhou, Mei-fang Zhu
Progress in Natural Science: Materials International 2012 Volume 22(Issue 4) pp:288-294
Publication Date(Web):August 2012
DOI:10.1016/j.pnsc.2012.06.004
Graphite nanosheets (GNS) were prepared by surfactant assisted ultrasonication from expanded graphite (EG) and followed by coating onto vinylon fabrics with water-borne polyurethane (WPU). The morphology of GNS and GNS/polyurethane (PU) coatings was characterized by field emission scanning electron microscope (FESEM), and the structure of GNS was studied by fourier transform infrared (FTIR) spectroscopy. Electromagnetic (EM) parameters indicated that GNS is a kind of dielectric loss material, in which little magnetic loss is found. Reflection loss (RL) results showed that both GNS content and coated thickness had great influences on the microwave absorption. For the fabric coated with GNS/PU nanocomposites (30/100 by weight, wet thickness of 0.39 mm for dry areal density in 130 g/m2), RL values exceeding −5 dB could be obtained in the frequency range of 10.7–18 GHz, while −10 dB in 12.7–18 GHz, and a minimum value of −28 dB at 15.2 GHz. These GNS/PU coated fabrics are light and flexible with much thin and low-cost coated layer, and showed great potential in radar camouflaging and electromagnetic interference application.
Co-reporter:Xuefen Wang, Kai Zhang, Yin Yang, Lili Wang, Zhe Zhou, Meifang Zhu, Benjamin S. Hsiao, Benjamin Chu
Journal of Membrane Science 2010 Volume 356(1–2) pp:110-116
Publication Date(Web):1 July 2010
DOI:10.1016/j.memsci.2010.03.039
In this work, a new strategy for fabrication of high flux thin film nanofibrous composite (TFNC) ultrafiltration membrane containing a hydrophilic barrier layer and a nanofibrous substrate was developed. Firstly, the double-layer nanofibrous mat containing very thin hydrophilic nanofiber top layer and nanofibrous supporting layer was manufactured via electrospinning technique. Then the hydrophilic nanofibrous top layer was remelted by suitable solvent vapor exposure and chemical crosslink in the crosslinking bath to form a barrier film on the supporting layer. Here, poly(vinyl alcohol) (PVA)/polyacrylonitrile (PAN) nanofibrous composite membranes were prepared by electrospinning of a very thin PVA nanofibrous layer with thickness of several micrometers on the electrospun PAN nanofibrous substrate, followed by remelting PVA nanofibrous layer to form a barrier PVA film by water vapor treatment and chemical crosslinking in glutaraldehyde water/acetone solution. The depositing time during PVA electrospinning and the water content of the crosslinking solution were utilized to control the thickness and the swelling degree of the PVA barrier layer. In this method, the shortcoming of easy penetration of the coating solution into the porous substrate in typical fabrication of surface coated anti-fouling composite membranes can be overcome, and the thickness of the barrier layer can be easily controlled by the depositing time of the PVA electrospinning. Filtration performances of the PVA/PAN composite membranes were evaluated by the oil/water emulsions separation system. The highest permeate flux of 210 l/m2h was achieved with the rejection of 99.5% for the composite membrane under the operating pressure of 0.3 MPa. It is believed that the strategy for fabricating TFNC membranes described here can be extended easily to fabricate nanofibrous composite membranes from many other polymeric materials simply by choosing the suitable solvent vapor treatment.
Co-reporter:Liping Zhu;Yaogang Li;Qinghong Zhang;Hongzhi Wang
Biomedical Microdevices 2010 Volume 12( Issue 1) pp:169-177
Publication Date(Web):2010 February
DOI:10.1007/s10544-009-9373-x
We report a novel and facile method for fabricating coaxial microfluidic devices processing various dimensions at low cost, in which polypropylene hollow fibers or glass capillaries are used as the tip of the dispersed phase injection tube. With this coaxial microfluidic device, monodisperse biocompatible microspheres ranging from 300 to 800 μm were obtained by collecting oil-in-water or water-in-oil emulsions and solidifying the suspended microspheres. Microsphere size could be controlled by changing the tips or tuning the concentrations of the dispersed and continuous phases. By adding functional nanoparticles into the dispersed phase, it was demonstrated that fluorescent and magnetic microspheres can be fabricated easily using these microfluidic devices.
Co-reporter:Jiang Yongmei;Liu Yang;Ma Yun;Liu Xiaoli;Qin Zongyi;Zhu Meifang;H. J. Adler
Macromolecular Symposia 2008 Volume 264( Issue 1) pp:95-99
Publication Date(Web):
DOI:10.1002/masy.200850415
Abstract
Novel interpenetrating networks (IPNs) hydrogels responsive to temperature were prepared in situ by liquid-phase photopolymerization. The first network of the IPNs (poly isopropyl acrylamide) were formed with a special kind of hectorite (Laponite XLS) modified by tetrasodium pyrophosphate as cross-linker and 2-oxogultaric acid as photoinitiator. The samples were subsequently immersed in an acrylamide (AAm) aqueous solution for at least one day for preparing IPNs hydrogels, in which acrylamide aqueous solution containing N,N′-Dimetyl acrylamide (MBAA) as cross-linker and 2-oxogultaric acid as photoinitiator. Then the second networks were in situ formed by introducing ultraviolet light irradiated PNIPAAm gels. The swelling/deswelling behaviors of IPNs hydrogels were measured. Compared with the corresponding nanocomposite PNIPAAm hydroges(NC hydrogels), chemically cross-linked PNIPAAm and PAAm IPNs hydrogels, the results indicate that the new IPN hydrogel has a faster deswelling rate above its LCST (≈32 °C). The effect was explained as being an additional contribution of the PAAm chains in IPN hydrogels, which may act as a water-releasing channel when the hydrophobic aggregation of PNIPA takes place.
Co-reporter:Qinghua Zhang, Fang Fang, Xin Zhao, Yingzhi Li, Meifang Zhu and Dajun Chen
The Journal of Physical Chemistry B 2008 Volume 112(Issue 40) pp:12606-12611
Publication Date(Web):September 12, 2008
DOI:10.1021/jp802708j
Well-dispersed multiwalled carbon nanotube (MWNT)/polystyrene composites have been prepared. Transmission and scanning electron microscopy were employed to observe the distribution of the MWNTs in the composites in a microscopic scale, indicating a nanotube network formed in the matrix. The dispersion of the nanotubes in the polymer was monitored by oscillatory rheology. It was found that the addition of MWNTs in the polymer had a drastic influence on the rheological behavior of the composites. As the MWNT loading increased, Newtonian behavior disappeared at low frequency, suggesting a transition from liquid-like to solid-like viscoelastic behavior. A more homogeneous dispersion or a greater loading of the nanotubes in the matrix produced stronger solid-like and nonterminal behavior, and the composites exhibited less temperature dependence at elevated temperature, compared to the matrix melt.
Co-reporter:Huiqun Cao, Meifang Zhu, Yaogang Li, Jianhong Liu, Zhuo Ni, Zongyi Qin
Journal of Solid State Chemistry 2007 Volume 180(Issue 11) pp:3218-3223
Publication Date(Web):November 2007
DOI:10.1016/j.jssc.2007.08.018
Novel magnetic composites (Ni0.5Zn0.5Fe2O4–MWCNTs) of multi-walled carbon nanotubes (MWCNTs) coated with Ni0.5Zn0.5Fe2O4 nanocrystals were synthesized by chemical precipitation–hydrothermal process. The composites were characterized by X-ray powder diffractometer (XRD), X-ray photoelectron spectrometer (XPS), Fourier transform infrared spectroscopy (FTIR), Mössbauer spectroscopy (MS), transmission electron microscopy (TEM), and selected area electron diffraction (SAED), etc. A temperature of about 200 °C was identified to be an appropriate hydrothermal condition to obtain Ni0.5Zn0.5Fe2O4–MWCNTs, being lower than the synthesis temperature of a single-phase Ni0.5Zn0.5Fe2O4 nanocrystals. The sizes of Ni0.5Zn0.5Fe2O4 in the composites were smaller than those of Ni0.5Zn0.5Fe2O4 nanocrystals in single phase. The composites exhibited more superparamagnetic than Ni0.5Zn0.5Fe2O4 nanocrystals in their relaxation behaviors. The magnetic properties measured by a vibrating sample magnetometer showed that the composites had a high coercive field of 386.0 Oe at room temperature, higher than those of MWCNT and Ni0.5Zn0.5Fe2O4 nanocrystals.Novel magnetic composites (Ni0.5Zn0.5Fe2O4–MWCNTs) of multi-walled carbon nanotubes (MWCNTs) coated with Ni0.5Zn0.5Fe2O4 nanocrystals were synthesized by chemical precipitation–hydrothermal process. The composites had a high coercive field of 386.0 Oe, higher than those of MWCNT and Ni0.5Zn0.5Fe2O4 nanocrystals.
Co-reporter:Chunju Gu;Bin Sun;Wenhua Wu;Fengchuan Wang
Macromolecular Symposia 2007 Volume 254(Issue 1) pp:160-166
Publication Date(Web):10 AUG 2007
DOI:10.1002/masy.200750825
Summary: Copper-loaded carboxymethyl-chitosan (CMCS-Cu) nanoparticles were successfully prepared by chelation under aqueous conditions. The effect of degree of deacetylation and substitution, the molecular weight of CMCS, CMCS concentration, Cu(II) ions concentration, pH value of the solution, as well as temperature, on the morphology of the yielded particles were systematically investigated. The physicochemical properties of the particles were determined by size and zeta potential analysis, FTIR analysis, DLS, TEM, SEM and XRD pattern. FTIR and XRD revealed that Cu (II) ions and CMCS formed a chelate complex. The size of CMCS-Cu particles shows a good consistency by DLS, TEM, and SEM. The nanoparticles with the size of about 70 nm have been prepared at 0.13 wt% CMCS, 16 mmol/L Cu(II) ions, pH value 4.56 at 25 °C. The antibacterial activity of CMCS, CMCS-Cu normal particles with the size of about 1000 nm and CMCS-Cu nanoparticles with the size of less than 100 nm against Staphylococcus aureus was evaluated by vibration method. Results show that the antibacterial efficiency of nanoparticles reached 99%, which is much more efficient than 68.9% of the normal one and 6.1% of CMCS. CMCS-Cu nanoparticles were proved to be a good novel antibacterial material.
Co-reporter:Cao Huiqun, Zhu Meifang, Li Yaogang
Journal of Solid State Chemistry 2006 Volume 179(Issue 4) pp:1208-1213
Publication Date(Web):April 2006
DOI:10.1016/j.jssc.2005.12.040
A magnetic composite of multiwalls carbon nanotubes (MWNTs) decorated with iron oxide nanoparticles was synthesized successfully by a simple and effective chemistry precipitation method. The composite was characterized by X-ray diffraction analysis (XRD), Mössbauer spectrum (MS), transmission electron microscopy (TEM), and Fourier transform spectroscopy (FTIR) techniques. The patterns of XRD and MS indicated that MWNTs, γ-Fe2O3, and Fe3O4 coexisted in the composite. The TEM observation indicated that the nanoparticles of iron oxide were attached on the surface of the MWNTs, and the sizes of the particles ranged from 25 to 80 nm. FTIR spectra showed that SO4− functional groups existed on the surface of MWNTs after modification by sodium dodecylbenzene sulfonic acid (SDBS), which could immobilize Fe3+ ions onto the MWNTs. The hysteresis loops of the MWNTs and decorated MWNTs were measured by vibrating sample magnetometer (VSM), and the results showed that the composite was ferromagnetism with the saturated magnetization of 20.07 emu/g, and the coercive of 163.44 Oe.TEM images of MWNTs decorated with iron oxide nanoparticles
Co-reporter:Xin Huang;Hao Yu;Mei-Fang Zhu;Yan-Mo Chen
Journal of Applied Polymer Science 2005 Volume 96(Issue 6) pp:2360-2366
Publication Date(Web):14 APR 2005
DOI:10.1002/app.21663
Blends of polypropylene (PP) and modified atactic polystyrene (PS) with good processability were studied for dyeable fine and superfine fibers. Acrylic acid and butyl acrylate monomers were added to PS by radical suspension copolymerization. The dispersion of the additives in the PP crystal was investigated. The rheology curves of the blends were similar to that of PP under the testing conditions. Fine and superfine PP filaments were processed from these blends, and they had practical mechanical properties. The dyeability of the fabrics from the fibers was studied. The increased amorphous content and the interface between PP and modified PS allowed the dyes to penetrate the fibers. These two effects helped to improve the color intensity. The color fastness was also improved by the presence of polar groups introduced by the modified PS components. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2360–2366, 2005
Co-reporter:Weiwei Zuo;Hao Yu;Wen Yang;Yanmo Chen;Yu Zhang
Polymer Engineering & Science 2005 Volume 45(Issue 5) pp:704-709
Publication Date(Web):14 MAR 2005
DOI:10.1002/pen.20304
Ultrafine fibers produced by electrospinning often exhibit bead-on-string structures, which have generally been considered to be undesirable “by-products” or defects. Theoretical analysis in the literature predicted three types of instabilities for an electrically driven jet: the axisymmetric Rayleigh instability, the electric field-induced axisymmetric, and whipping instability. The process of bead formation revealed that the formation of a beaded structure resulted from axisymmetric deformation and flow of the jet. Applied voltage, solution surface tension, and conductivity (or jet charge density carried by the moving jet) were theoretically demonstrated to be important for jet axisymmetric instabilities. Experimental results revealed that these parameters influenced the formation of beaded fibers in the same manner as they did for the axisymmetric instabilities. As a result, the axisymmetric instabilities were considered to be the most likely mechanism of beaded fibers formation during electrospinning. POLYM. ENG. SCI., 45:704–709, 2005. © 2005 Society of Plastics Engineers
Co-reporter:Houkang He;Yanmo Chen;Qiang Xing;Yu Zhang;Petra Pötschke;Hans-Jürgen Adler
Macromolecular Symposia 2004 Volume 210(Issue 1) pp:251-261
Publication Date(Web):4 MAY 2004
DOI:10.1002/masy.200450629
In this work, surface modification technique with coupling agents and anchoring polymerization was adopted to tailor the surface properties of nanoscaled titanium dioxide (TiO2). Ethyl glycol sols with TiO2 were prepared in order to simulate the dispersibility of differently modified TiO2 in a molten polyamide 6 (PA6) matrix. The modified TiO2 were melt compounded with PA6 and composites and fibers were prepared. The average filler diameter of 47 nm (in composites) and 44 nm (in fibers) indicated homogeneous dispersion of TiO2 in the matrix, whereas unmodified TiO2 showed agglomerated structures in the PA6 matrix. The mechanical properties of the composite fibers were improved as compared to pure PA6 fibers and composite fibers with unmodified TiO2.
Co-reporter:Meifang Zhu;Hao Yu;Yanmo Chen;Yu Zhang;H.J. Adler;Liyuan Song;Long Chen
Macromolecular Symposia 2004 Volume 210(Issue 1) pp:241-250
Publication Date(Web):4 MAY 2004
DOI:10.1002/masy.200450628
Crystallization behavior of blends of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(1,2-propandiolcarbonate) (PR(CO2)) has been investigated by polarized light microscopy (PLM). The spherulite growth rates (SGR) of all blends were faster than that of pure PHBV, and the spherulite growth rates of PHBV in the PHBV/PR(CO2) blends reduced with increasing PR(CO2) weight fraction. There are two melting peaks in both the pure PHBV and the PHBV/PR(CO2) blends. The melting peak of PHBV/PR(CO2) blends was reduced by lower temperature about 20K as compared to PHBV and the higher temperature melting peak was increased by about 10K in the blends.
Co-reporter:Hao You, Xiong Li, Yin Yang, Baoyi Wang, Zhuoxi Li, Xuefen Wang, Meifang Zhu, Benjamin S. Hsiao
Separation and Purification Technology (19 April 2013) Volume 108() pp:143-151
Publication Date(Web):19 April 2013
DOI:10.1016/j.seppur.2013.02.014
In this study, a new class of high performance thin film nanocomposite (TFNC) ultrafiltration membrane based on a polyacrylonitrile (PAN) nanofibrous substrate coupled with a thin hydrophilic nanocomposite barrier layer was fabricated by electrospinning technique combined with solution treatment method, and was used as an ultrafiltration media to separate an oil/water emulsion. The hydrophilic nanocomposite barrier layer was composed of crosslinked poly(vinyl alcohol) (PVA) thin layer incorporating surface oxidized multi-walled carbon nanotubes (MWNTs), and was prepared by immersing electrospun PVA–MWNT/PAN nanofibrous double-layer mats into optimized water/acetone solution and then chemically crosslinked by glutaraldehyde in water/acetone solution. The electrospun PVA–MWNT nanofiber top layer would be swollen to merge imperceptibly into an integrated barrier film on the supporting PAN layer. The variation of the free volume of PVA barrier layer with different MWNTs contents was investigated by positron annihilation lifetime spectroscopy (PALS). The PALS results proved that the free volume of PVA–MWNT/PAN TFNC membranes increased markedly with the increase of MWNTs concentration in the PVA layer, and the filtration evaluation also confirmed that the incorporation of MWNTs into PVA barrier layer could improve the water flux significantly, which indicated that more effective water channels were generated in the nanocomposite barrier layer by the incorporation of MWNTs into PVA barrier layer. The PVA–MWNT/PAN TFNC (10 wt.% MWNT) membrane showed very high water flux (270.1 l/m2 h) with high rejection rate (99.5%) even at very low feeding pressure (0.1 MPa). In addition, the PVA–MWNT/PAN composite membranes showed very good overall mechanical properties.Highlights► High flux low pressure thin film nanocomposite filtration membranes were prepared. ► PVA–MWNT/PAN nanofibrous double layer mats were prepared by electrospinning. ► Electrospun PVA–MWNT top layer was solution treated to an integrated barrier film. ► The free volume characteristics of the PVA–MWNT barrier layers were studied. ► Filtration performances of the PVA–MWNT/PAN nanocomposite membranes were evaluated.
Co-reporter:Jianyong Feng, Deteng Zhang, Meifang Zhu and Changyou Gao
Journal of Materials Chemistry A 2017 - vol. 5(Issue 26) pp:NaN5188-5188
Publication Date(Web):2017/05/26
DOI:10.1039/C7TB00601B
Aligned fiber scaffolds can mimic the parallel aligned fibrils in the extracellular matrix (ECM) of bones, and thus regulate many cellular behaviors. The aligned scaffolds are usually prepared by a microplate micropatterned method, freeze casting, evaporation, slip casting, ice-templating, plain weaving, and fiber forming techniques. In this study, the melt spinning technology, which has the advantages of a higher spinning speed, solvent-free processing and readily scalable production, was used to prepare poly(L-lactide) (PLLA) melt spun fibers with an average diameter of 70.3 ± 11.4 μm. The fibers were further bonded by 5% PLLA tetrahydrofuran solution to prepare PLLA spun fiber-aligned scaffolds. Collagen and chitosan molecules were coated onto the fibers/into the scaffolds to obtain multiple biochemical and surface aligned topography cues, respectively. The collagen or chitosan-coated PLLA aligned scaffolds could effectively improve the viability, adhesion, length and migration behaviors of osteoblasts in vitro. In particular, the collagen coated aligned scaffold had the largest cell length and the fastest migration rate, with a preferential direction along the fibers. This type of scaffold provides a versatile substrate to control cell behaviors, having great potential for bone regeneration.
Co-reporter:Yanhua Cheng, Gen Chen, Haobin Wu, Meifang Zhu and Yunfeng Lu
Journal of Materials Chemistry A 2017 - vol. 5(Issue 27) pp:NaN13949-13949
Publication Date(Web):2017/06/28
DOI:10.1039/C7TA03043F
Building nanocomposite architectures based on carbon nanotubes (CNTs) and active nanoparticles (NPs) with an engineered interface is of great interest for developing the ability to store electrochemical energy. The use of cellulose to direct hetero-assembly was achieved by in situ regenerating an ionic liquid mixture (CNTs, NPs, cellulose) in water, and was applied to the fabrication of flexible anodes consisting of CNTs and NPs. These anodes showed CNTs threading through their structures and exhibited strong interfacial contacts, which provided a relatively short lithium-ion diffusion length and continuous electron conduction pathway as well as high mechanical stability. When evaluated as an anode material for a lithium-ion battery, the flexible nanocomposites showed high reversible capacity and good rate performance compared to traditionally made electrodes, demonstrating a simple and green strategy for the industrial-scale production of energy-storage devices.
Co-reporter:Wenju Xu, Qiyun Tian, Zhigang Chen, Mengge Xia, Daniel K. Macharia, Bin Sun, Ling Tian, Yifei Wang and Meifang Zhu
Journal of Materials Chemistry A 2014 - vol. 2(Issue 34) pp:NaN5601-5601
Publication Date(Web):2014/06/25
DOI:10.1039/C4TB00669K
Near-infrared (NIR) laser-induced photothermal ablation (PTA) therapy has great potential to revolutionize conventional therapeutic approaches for cancers, and a prerequisite is to obtain biocompatible and efficient photothermal agents. Herein, we have developed hydrophilic W18O49 nanowires with average lengths of about 800 nm (abbreviated as W18O49-800 NWs) as an efficient photothermal agent, which are prepared by the solvothermal synthesis—simultaneous PEGylation/exfoliation/breaking two-step route. These W18O49-800 NWs exhibit stronger NIR photoabsorption than short nanowires with average lengths of about 50 nm (abbreviated as W18O49-50 NWs) that are prepared via a solvothermal one-step route. Under irradiation of 980 nm with a safe intensity of 0.72 W cm−2, the aqueous dispersion of W18O49-800 NWs (1.0 mg mL−1) exhibits the temperature elevation by 35.2 °C in 5 min; which is a 37.5% increase compared to that (by 25.6 °C) from W18O49-50 NWs (1.0 mg mL−1). More importantly, under 980 nm laser irradiation (0.72 W cm−2) for 10 min, in vivo cancer cells can be efficiently ablated by the photothermal effects of W18O49-800 NWs. Therefore, these W18O49-800 NWs can be used as a more efficient and promising photothermal nanoagent for the ablation of cancer cells in vivo.
