Co-reporter:Cong Zhang, Jihong Wen, Jing Yan, Yanbing Kao, Zhiqiang Ni, Xuejun Cui and Hongyan Wang
RSC Advances 2015 vol. 5(Issue 16) pp:12123-12130
Publication Date(Web):08 Jan 2015
DOI:10.1039/C4RA16609D
Uniaxially aligned composite fibrous scaffolds of gelatin and poly-L-lactic acid (PLLA) were fabricated using electrospinning and the scaffolds were implanted into the corneal stroma layers of New Zealand white rabbits (NZWRs) to observe the in situ growth induction of the stroma cells. The effects on cell growth were evaluated by both apparent observation and pathological analysis. It was demonstrated that the scaffolds had a good compatibility with the corneal tissues and were nontoxic by observing the changes of the structure and the physiological activity of the corneal tissues around the scaffolds using a slit lamp and in vivo confocal images. The in vivo confocal images of the scaffolds implanted into the eyes of NZWRs show the process of the cells’ ingrowth and the tissue regeneration, which indicated that the uniaxially aligned fibers could induce the polarized ingrowth of keratocytes which may provide the basis for clinical application to the in situ repair of corneal stromata.
Co-reporter:Zhijun Wang, Sunhua Deng, Qiang Gu, Xuejun Cui, Yumin Zhang, and Hongyan Wang
Energy & Fuels 2014 Volume 28(Issue 4) pp:2305
Publication Date(Web):March 17, 2014
DOI:10.1021/ef5000062
Isothermal subcritical water extraction technique was used to extract organic matters from Huadian oil shale under different extraction conditions. The effects of particle size, extraction temperature, extraction time, and water–oil shale mass ratio were investigated on the extracts yield. A series of extraction experiments were carried out with three particle size samples and the water–oil shale mass ratio in the range 1.5–3.5 at five levels of temperature for 5–70 h. As a result, extraction temperature and extraction time were found to have large effect on the extracts yield, and the particle size had large effect on the extracts yield at 335 °C. The maximum extracts yield could be obtained at 365 °C for 30 h with the water–oil shale mass ratio of 3 using middle particle size oil shale samples. Gas chromatography–mass spectrometry (GC-MS) analysis of the n-hexane-soluble maltene in bitumen 1 and the organic matters in the spent aqueous solution demonstrated that large molecular hydrocarbons could be cracked into smaller hydrocarbon compounds with the extending of extraction time. The elemental analysis of the bitumen 1 showed that the atomic H/C reached the maximum value of 1.82 wt % when the extraction time was 15 h. The analysis results of the pyrolysate indicated that subcritical water played the roles of catalytic pyrolysis and extraction solvent during extraction process.
Co-reporter:Sunhua Deng, Zhijun Wang, Yan Gao, Qiang Gu, Xuejun Cui, Hongyan Wang
Journal of Analytical and Applied Pyrolysis 2012 Volume 98() pp:151-158
Publication Date(Web):November 2012
DOI:10.1016/j.jaap.2012.07.011
Three sizes of Huadian oil shale lumps from 1 cm to 10 cm were extracted by sub-critical water at 350 °C and 16 MPa for 2–70 h. The oil shale lumps were fractured alone the shale texture in sub-critical water that greatly improved the extraction efficiency of bitumen from the large- and middle-sized sample. The extract yields of bitumen from different sized samples were similar when the extraction time is longer than 20 h and stabilized at about 18 wt.% (ad) after 50 h duration. With the increase of extraction time, asphaltene and preasphaltene extracts were gradually decomposed to maltene. The gas chromatography–mass spectrometry (GC–MS) analysis of the extracts showed that n-alkanes, n-alk-1-enes, isoprenoids, n-alk-2-ones and n-alkanoic acids were the major components. In contrast, aromatic extracts were rare and most of them were remained in the shale residue. The pyrolysis gas chromatography–mass spectrometry (Py-GC–MS) analysis of the spent shale showed that the final undecomposed organics in kerogen were some macromolecular linear hydrocarbon, n-alk-2-ones and n-alkanoic acids fragments. The comparison of the classical pyrolyzate and the sub-critical water extracts showed that the water extracts contained more long-chain alkanes than anhydrous pyrolysis and the alkene extracts could transform to alkanes in sub-critical water. Moreover, the n-alkanoic acids could be decomposed to short-chain compounds through the cleavage of carbon carbon bonds.Highlights► Oil shale lumps are fractured alone the shale texture in sub-critical water. ► Long-chain molecules are further cracked to shorter-chain compounds in sub-critical water. ► Alkenes are gradually reacted in sub-critical water when extended the extracting time. ► Alkanoic acids are decomposed through the CC bonds in sub-critical water. ► Released aromatics are almost phenols and ketones and most are surviving in the oil shale.
Co-reporter:Jing Yan;Linhui Qiang;Yan Gao;Xuejun Cui;Hongyan Zhou;Shuangling Zhong;Qing Wang
Journal of Biomedical Materials Research Part A 2012 Volume 100A( Issue 2) pp:527-535
Publication Date(Web):
DOI:10.1002/jbm.a.33301
Abstract
The contribution of fiber alignment of scaffold on cellular mechanisms was evaluated by a comparative study of two different cells sourced from cornea. Electrospun scaf-folds with similar composition and comparable fiber size were fabricated into randomly oriented and aligned scaffolds, which bear paralleled degradation of gelatin. Tensile test of wet scaffolds indicated that fiber alignment could influence its mechanical properties. Due to the unidirectional fiber orientation, aligned scaffold exhibited higher tensile modulus, higher break strength, and lower elongation at break than randomly oriented scaffold. The effect of fiber alignment on cells behavior was evaluated by cell morphology, specific protein expression, adhesion, and proliferation. Different corneal cells responded uniquely to fiber alignment of scaffold, keratocytes interacting more favorably on alignment scaffold and corneal epithelial cells more favorably on randomly oriented scaffold. These results confirmed that fiber alignment of scaffold would be benefit for cell proliferation if its contact guidance coincided with the cell shape and cytoskeletal tension. This finding is important to envisage an advanced composite scaffold that incorporates randomly oriented and aligned fibers for the growth and control of different cell types required for the successful development of corneal grafts by tissue engineering. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
Co-reporter:Xuejun Cui;Yan Gao;Shuangling Zhong;Zaihang Zheng
Journal of Polymer Research 2012 Volume 19( Issue 3) pp:
Publication Date(Web):2012 March
DOI:10.1007/s10965-012-9832-6
Semi-interpenetrating polymer networks (Semi-IPNs) based on fluorine-containing polyacrylate and epoxy resin were synthesized by the simultaneous polymerization of fluorine-containing acrylate and epoxy resin. Fourier transform infrared (FTIR) spectrometry and X-ray photoelectron spectroscopy (XPS) analyses proved that the fluorine-containing groups have been introduced into Semi-IPNs successfully. In addition, XPS analysis intuitively showed that the fluorine content of the film-air interface of the interpenetrating fluorine-containing polyacrylate and epoxy resin networks (FPAER-SIPNs) film was much higher than that of the film-glass interface. It is noted that the introduction of fluorine-containing groups significantly improved the hydrophobic property of polymer networks. Moreover, when the fluorine content increased, the contact angle of water on FPAER-SIPNs film was increased obviously and the water uptake was decreased gradually. These results indicated that introducing fluorine-containing groups to SIPNs has potential advantage for improving the surface properties of epoxy resin.
Co-reporter:Chunlei Wang, Juntao Yan, Xuejun Cui, Hongyan Wang
Journal of Colloid and Interface Science 2011 Volume 354(Issue 1) pp:94-99
Publication Date(Web):1 February 2011
DOI:10.1016/j.jcis.2010.09.078
In this paper, we present a novel method for the preparation of raspberry-like monodisperse magnetic hollow hybrid nanospheres with γ-Fe2O3@SiO2 particles as the outer shell. PS@Fe3O4@SiO2 composite nanoparticles were successfully prepared on the principle of the electrostatic interaction between negatively charged silica and positively charged polystyrene, and then raspberry-like magnetic hollow hybrid nanospheres with large cavities were achieved by means of calcinations, simultaneously, the magnetite (Fe3O4) was transformed into maghemite (γ-Fe2O3). Transmission electron microscopy (TEM) demonstrated that the obtained magnetic hollow silica nanospheres with the perfect spherical profile were well monodisperse and uniform with the mean size of 253 nm. The Fourier transform infrared (FTIR) spectrometry, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) provided the sufficient evidences for the presence of Fe3O4 in the silica shell. Moreover, the magnetic hollow silica nanospheres possessed a characteristic of superparamagnetic with saturation magnetization value of about 7.84 emu/g by the magnetization curve measurement. In addition, the nitrogen adsorption–desorption measurement exhibited that the pore size, BET surface area, pore volume of magnetic hollow silica nanospheres were 3.5–5.5 nm, 307 m2 g−1 and 1.33 cm3 g−1, respectively. Therefore, the magnetic hollow nanospheres possess a promising future in controlled drug delivery and targeted drug applications.Graphical abstractA facile method is presented for the preparation of raspberry-like monodisperse hollow hybrid nanospheres with γ-Fe2O3@SiO2 particles as the outer shell via sol–gel process.Research highlights► A facile method for preparing raspberry-like magnetic hollow nanospheres was developed. ► The Fe3O4@SiO2 particles were shapely coated on the surface of PS templates. ► The hollow nanospheres were well monodisperse and uniform with a size of 253 nm. ► The hollow nanospheres possessed large cavities and excellent magnetic properties.
Co-reporter:Sunhua Deng, Zhijun Wang, Qiang Gu, Fanyu Meng, Junfeng Li, Hongyan Wang
Fuel Processing Technology 2011 Volume 92(Issue 5) pp:1062-1067
Publication Date(Web):May 2011
DOI:10.1016/j.fuproc.2011.01.001
The possibility of extracting hydrocarbons from Huadian oil shale by sub-critical water was found in a stainless steel vessel. The effects of temperature and pressure on the extraction of hydrocarbons were studied. After extraction experiments, the residual solid, liquid and gas phase samples were collected and characterized, respectively. The extract yield could reach 7 wt.% (ad) when the extraction of oil shale was conducted at 260 °C for 2.5 h with the pressure of 15 MPa. The results of thermogravimetry (TG) showed that the weight loss of residual solid samples was much smaller than that of the original oil shale. It indicated that kerogen components had been decomposed partly by treatment with sub-critical water. Gas chromatography–mass spectrometry (GC–MS) analysis showed that there were more than 300 recognizable peaks in the extracting solution following processing at 330 °C and 18 MPa. Large amounts of high molecular weight hydrocarbons were gradually decompounded by the increase in types and levels of low molecular weight hydrocarbons, and polycyclic and heterocyclic compounds with the rising of pressure and temperature. These indicated that sub-critical water is capable of cracking kerogen into smaller hydrocarbon compounds at relatively low temperatures.
Co-reporter:Yongchao Zhao, Linhui Qiang, Juntao Yan, Shijin Dong, Qiaoyun Zhang, Lisi Zhang, Xuejun Cui, Hongyan Wang
Applied Surface Science 2011 Volume 257(Issue 9) pp:4377-4383
Publication Date(Web):15 February 2011
DOI:10.1016/j.apsusc.2010.12.066
Abstract
A preparation method of waterborne crackle decorative coatings was reported in this paper and the factors that influence crack patterns were investigated. The crackle coating consisted of a waterborne basecoat and a waterborne topcoat. The basecoat was made from two-component epoxy emulsion and the topcoat was made from fluorine-containing acrylic emulsion, silicone-acrylic emulsion or styrene-acrylic emulsion. Three junction types of crack patterns were prepared by the three top coatings, which were T-junction, Y-junction and mixed junction. T-junction type with long and straight cracks was prepared from styrene-acrylic emulsion 296DS. Y-junction type with curve and short cracks was prepared from fluorine-containing acrylic emulsion A603C and mixed junctions type was made from silicone-acrylic emulsion. Crack patterns with different spacing were prepared by controlling the thickness of topcoat, dryness of basecoat or conditions of film forming. The characterize methods of type and spacing for crack pattern were developed and properties of coating film including adhesion, water resistance, scrub resistance and so on were tested. The results showed that the crackle coatings possessed satisfactory properties for practical application.
Co-reporter:Jia Xu, Jing Yan, Qiang Gu, Junfeng Li, Hongyan Wang
Materials Letters 2011 Volume 65(15–16) pp:2404-2406
Publication Date(Web):August 2011
DOI:10.1016/j.matlet.2011.04.080
A novel material, fluoride-containing gelatin nanofiber scaffold, was prepared by electrospinning process successfully. Scanning electron microscopy (SEM) image showed that the morphology of nanofibers was uniform and smooth, and the average diameter was about 200 nm. An even distribution in the fiber matrix of some nanoparticles which is about 20 nm was also observed in transmission electron microscopy (TEM) images. X-ray diffraction (XRD) demonstrated that the nanoparticles dispersed in the gelatin fiber matrix were CaF2 crystals. This scaffold was crosslinked with glutaraldehyde (GTA) vapor at room temperature for 4 days in order to improve the water-resistant ability. After soaking in Dulbecco's Modified Eagle's Medium (DMEM) solution (37 °C) for 4 weeks the crosslinked scaffold still maintained a good appearance and morphology. All the properties of this novel material show a good potential to be a bone tissue engineering scaffold.
Co-reporter:Juntao Yan;Xiaojie Miao;Qiaoyun Zhang;Xuejun Cui;Junfeng Li
Polymer Engineering & Science 2011 Volume 51( Issue 2) pp:294-301
Publication Date(Web):
DOI:10.1002/pen.21829
Abstract
A facile one-step technique of preparing black polystyrene (PS) was developed by in situ suspension polymerization in which polymerization of styrene was conducted in the presence of modified carbon black (CB). A series of uniform black PS particles had been synthesized with this method. Morphology and dispersion stability of the various CBs were investigated by both scanning electron microscopy and spectrophotometric analysis. The results of thermogravimetric analysis indicated that the thermal stability of PS was significantly enhanced by introducing modified CB. In addition, the PS synthesized in the absence or presence of modified CB possessed a narrow molecular distribution, as was characterized by gel permeation chromatography. Compared with the conventional mechanical blending technique of PS and CB, our present technique could not only avoid the drawback of poor miscibility between the CB and PS, but also simplify the synthesis technique. Scanning electron microscopy micrographs of the resulting black PS demonstrated that modified CB was well dispersed in the PS matrix. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers
Co-reporter:Qiushun Li, Xu-lin Zhang, Yong-Sen Yu, Ying Qian, Wen-Fei Dong, Yong Li, Jianguo Shi, Juntao Yan, Hongyan Wang
Reactive and Functional Polymers 2011 71(3) pp: 335-339
Publication Date(Web):1 March 2011
DOI:10.1016/j.reactfunctpolym.2010.11.012
The response laws of long period fiber grating (LPFG) coated with polyelectrolyte multilayers (PEMs) of poly(allylamine hydrochloride) (PAH)/poly(sodium-p-styrenesulfonate) (PSS) to a series of concentration of sucrose solutions were investigated. Experimental results showed that the central wavelengths of LPFG spectra move to short-wave as concentration of sucrose solution increase. Pure LPFGs show the optimal sensitivity to 55–60% of sucrose solutions. With increasing number of the layers, the most sensitive regions of LPFGs to sucrose solutions will shift from high concentration to low concentration by matching average refractive index of films and sucrose solutions with that of LPFG cladding. LPFGs assembled with 100 bilayers of PAH/PSS exhibited the optimal sensitivity to 20–25% of sucrose solutions. However, LPFGs coated with 115 bilayers were more sensitive to a lower concentration (<5%) of sucrose solution. Therefore, the sensitivity of LPFG to the small molecular weight analytes can be strongly improved by designing the refractive index and thickness of PEM overlay, as confirmed and interpreted by theoretical simulations.
Co-reporter:Xuejun Cui, Shuangling Zhong, Jing Yan, Chunlei Wang, Haitao Zhang, Hongyan Wang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 360(1–3) pp: 41-46
Publication Date(Web):
DOI:10.1016/j.colsurfa.2010.02.006
Co-reporter:Chunlei Wang, Juntao Yan, Xuejun Cui, Dengli Cong, Hongyan Wang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 363(1–3) pp:71-77
Publication Date(Web):20 June 2010
DOI:10.1016/j.colsurfa.2010.04.016
Magnetic hollow polymethyl methacrylate (PMMA) nanospheres were successfully obtained by etching the template of CaCO3 in the core–shell Fe3O4@CaCO3@PMMA nanospheres, which were synthesized via in situ emulsion polymerization in the presence of oleic acid-modified Fe3O4@CaCO3 composite nanoparticles. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements demonstrated that the core–shell Fe3O4@CaCO3@PMMA nanospheres were uniform and possessed narrow size distributions. And a perfect spherical profile of magnetic hollow PMMA nanospheres could be also observed by TEM. Both the Fourier transform infrared (FTIR) spectrometry, high resolution TEM (HRTEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) provided the sufficient evidences for the presence of Fe3O4 in the magnetic hollow PMMA nanospheres. Thermogravimetric analysis (TGA) investigated the composition of the resulting composite nanospheres. Moreover, the magnetic testing experiment could give us a direct proof of the presence of Fe3O4 in magnetic hollow PMMA nanospheres. And the magnetic hollow PMMA nanospheres had a promising future in controlled drug delivery and targeted drug applications.
Co-reporter:Haitao Zhang;Zaihang Zheng;Xuejun Cui
Journal of Mathematical Chemistry 2010 Volume 48( Issue 3) pp:720-732
Publication Date(Web):2010 October
DOI:10.1007/s10910-010-9705-3
In order to quantify and predict the water resistance of membrane, a multi-scales association model was built up based on the Fick’s second law. Two water resistance indexes, balance time and seepage velocity, were put forward and calculated by the model for measuring the property of membrane water resistance. The association model linked macro-scale factors and micro-scale parameters together. The influence of macro-scale factors, environmental temperature and membrane thickness, and micro-scale parameters, water molecules diffusivity, membrane saturated water absorption rate and water escape concentration, were discussed. The properties of water resistances for two groups including 10 waterborne acrylate membranes samples were measured for validating the indexes calculated by the model. The well consistency between the results of calculations and experiments proved that the method of multi-scales association modeling for quantifying and predicting the membrane water resistance was feasible.
Co-reporter:Qiushun Li, Ying Qian, Yongsen Yu, Gang Wu, Zhenying Sui, Hongyan Wang
Optics Communications 2009 Volume 282(Issue 12) pp:2446-2450
Publication Date(Web):15 June 2009
DOI:10.1016/j.optcom.2009.03.007
In this paper, the ultrathin membranes of poly(sodium-p-styrenesulfonate) (PSS) and poly-dimethyl diallyl ammonium chloride (PDDA) are assembled on the surface of long period fiber gratings (LPFGs). The experiments indicate that the transmission spectra characteristics of LPFGs have greater change when bilayer number changed from 75 to 130. The action of sodium nitrite on the LPFGs is researched. The LPFGs without assembled films are not able to distinguish the concentrations of sodium nitrite solutions in the range of 0.001–0.2 mol/L. However, LPFGs assembled polyelectrolyte films of 130 bilayers have a higher distinguishability for these concentrations of sodium nitrite. With the increase of sodium nitrite concentrations, the center wavelengths of attenuation bands gradually shift towards the longer wavelength and represent a good linear relationship with concentrations. The method has the advantages such as low cost, no toxin, fast speed, no time limit. It is hopeful to be applied in real-time and on-line monitoring of sodium nitrite.
Co-reporter:Haitao Zhang, Yuan Zhou, Shijin Dong, Yongchao Zhao, Xuejun Cui, Hongyan Wang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2009 Volume 334(1–3) pp:171-175
Publication Date(Web):20 February 2009
DOI:10.1016/j.colsurfa.2008.10.034
Experiments and molecular dynamics simulations were combined to research the diffusion behavior of the chemisorbed and physisorbed water which is in the interior polyacrylate films in this paper. The water-endurance property of latex films was determined by the movement capability of the water molecules in them. The hydrogen bond interaction and the diffusion behavior was effect by the hydrophilic and hydrophobic functional group contents in the emulsion. The aqueous functionality of complex system, ϕ, was proposed in order to connect the property of monomers for simplified the hydrogen bond energy prediction. The water-endurance property of latex films was also reflected by the diffusion coefficient of the water. Therefore, the diffusion coefficient of the water was simulated by molecular dynamics (MD) method, which could reflect the water-endurance property of polyacrylate films in the microscopic scale. According to experiments, a water absorption ratio model related to aqueous functionality, diffusion coefficients and the interaction of them were constructed. Nine polyacrylate emulsions were prepared and their water absorption ratios were forecasted using the model having put forward. Comparing the results forecasted with determined, the mean relation error was less than 5%.
Co-reporter:Haitao Zhang;Yuan Zhou;Ping Cheng;Sunhua Deng
Journal of Mathematical Chemistry 2009 Volume 46( Issue 4) pp:1050-1059
Publication Date(Web):2009 November
DOI:10.1007/s10910-008-9489-x
Multi-objective simultaneous prediction of waterborne coating properties was studied by the neural network combined with programming. The conditions of network with one input layer, three hidden layers and one output layer were confirmed. The monomers mass of BA, MMA, St and pigments mass of TiO2 and CaCO3 were used as input data. Four properties, which were hardness, adhesion, impact resistance and reflectivity, were used as network output. After discussing the hidden layer neurons, learn rate and the number of hidden layers, the best net parameters were confirmed. The results of experiment show that multi-hidden layers was advantageous to improve the accuracy of multi-objective simultaneous prediction. 36 kinds of coating formulations were used as the training subset and 9 acrylate waterborne coatings were used as testing subset in order to predict the performance. The forecast error of hardness was 8.02% and reflectivity was 0.16%. Both forecast accuracy of adhesion and impact resistance were 100%.
Co-reporter:Xuejun Cui, Shuangling Zhong, Yan Gao, Hongyan Wang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2008 Volume 324(1–3) pp:14-21
Publication Date(Web):1 July 2008
DOI:10.1016/j.colsurfa.2008.03.018
The emulsifier-free core–shell interpenetrating polymer network (IPN) fluorinated polyacrylate latex particles with fluorine rich in shell were prepared by emulsifier-free seeded emulsion polymerization with water as the reaction medium. The fluorinated copolymer could be fixed on the particle surface due to the formation of interpenetrating polymer network. The resultant core–shell particles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) analysis, Fourier transform infrared (FTIR) spectrometry, X-ray photoelectron spectroscopy (XPS) analysis and thermogravimetric analysis (TGA). The core–shell particles possessed very narrow monomodal particle size distributions. XPS analysis of the latex film displayed that perfluoroalkyl groups had the tendency to enrich at surface and there was a gradient concentration of fluorine in the structure of the latex film from the film–air interface to the film–glass interface. In addition, compared with the latex film of crosslinked polyacrylate prepared under the same condition, the emulsifier-free core–shell IPN-fluorinated polyacrylate latex film showed better thermal stability, higher contact angle and lower water uptake.
Co-reporter:Xuejun Cui, Shuangling Zhong, Hongyan Wang
Journal of Power Sources 2007 Volume 173(Issue 1) pp:28-35
Publication Date(Web):8 November 2007
DOI:10.1016/j.jpowsour.2007.08.027
A series of silicon-containing polyacrylate nanoparticles (SiPANPs) were successfully synthesized by simple emulsifier-free emulsion polymerization technique. The resulting latex particles were characterized by Fourier transform infrared (FTIR) spectrometry, dynamic light scattering (DLS) analysis, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The SiPANP membranes and SiPANP/phosphotungstic acid (SiPANP/PWA) hybrid membranes were also prepared and characterized to evaluate their potential as proton exchange membranes in proton exchange membrane fuel cell (PEMFC). Compared with the pure SiPANP membrane, the hybrid membranes displayed lower thermal stability. However, the degradation temperatures were still above 190 °C, satisfying the requirement of thermal stability for PEMFC operation. In addition, the hybrid membranes showed lower water uptake but higher proton conductivity than the SiPANP precursor. The proton conductivity of the hybrid membranes was in the range of 10−3 to 10−2 S cm−1 and increased gradually with PWA content and temperature. The excellent hydrolytic stability was also observed in the hybrid membranes because of the existence of crosslinked silica network. The good thermal stability, reasonable water uptake, excellent hydrolytic stability, suitable proton conductivity and cost effectiveness make these hybrids quite attractive as proton exchange membranes for PEMFC applications.
Co-reporter:Xuejun Cui;Zhengxia Chen;Qiushun Li;Shuangling Zhong;Yinghua Wang
Journal of Applied Polymer Science 2007 Volume 105(Issue 4) pp:2138-2145
Publication Date(Web):26 APR 2007
DOI:10.1002/app.25664
Role of fluorocarbon surfactant in the preparation of polytetrafluoroethylene-modified polyacrylate emulsion is investigated. The fluorocarbon surfactant has an efficient preemulsification to polytetrafluoroethylene (PTFE) powder. It enables PTFE powder to be introduced into the copolymer of n-butyl acrylate, n-methyl methacrylate, n-styrene, and α-methacrylic acid. Thereby, stable PTFE-modified polyacrylate emulsion can be formed. The effects of fluorocarbon surfactant on the surface tension, particle size and particle size distribution of the emulsion, as well as the relation between fluorocarbon surfactant and the amount of PTFE powder are fully investigated. The particle size and the surface tension of emulsion strongly depend on the fluorocarbon surfactant concentration in the reaction system. The particle size distribution becomes narrower and the stability of the emulsion is improved with the increasing of the fluorocarbon surfactant concentration. According to the experiments, a possible mechanism of fluorocarbon surfactant in polymerization is proposed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007
Co-reporter:Shuangling Zhong;Qiang Gu;Junfeng Li;Haitao Zhang;Xuejun Cui
Polymers for Advanced Technologies 2007 Volume 18(Issue 7) pp:544-548
Publication Date(Web):8 MAY 2007
DOI:10.1002/pat.914
Polytetrafluoroethylene (PTFE)-polyacrylate core–shell nanoparticles were produced by using PTFE micropowder and acrylate via seeded emulsion polymerization in the presence of fluorosurfactant. The properties of emulsion under various polymerization conditions were investigated and optimized. The chemical composition of the PTFE-polyacrylate nanoparticles was characterized by Fourier-transform infrared spectrometry (FTIR). The particle size and core–shell structure of the resulting PTFE-polyacrylate nanoparticles were confirmed by transmission electron microscopy (TEM). Wettability of the PTFE-polyacrylate core–shell particles was higher than the pristine PTFE. The formation of this kind of PTFE-polyacrylate core–shell nanoparticles could improve the compatibility of PTFE with other materials because PTFE is covered by polyacrylate shell, which make them promising in various fields. Copyright © 2007 John Wiley & Sons, Ltd.
Co-reporter:Xuejun Cui;Shuangling Zhong;Jia Xu
Colloid and Polymer Science 2007 Volume 285( Issue 8) pp:935-940
Publication Date(Web):2007 May
DOI:10.1007/s00396-007-1651-7
Polytetrafluoroethylene (PTFE)/polyacrylate core-shell nanoparticles were produced via the emulsifier-free seeded emulsion polymerization of acrylate monomers with PTFE latex as seed. The monomer conversions under different synthesis parameters were monitored by a gravimetric method. The polymerization conditions for preparing PTFE/polyacrylate core-shell nanoparticles were surveyed and optimized. The chemical component of the PTFE/polyacrylate particles was confirmed by comparing the Fourier-transform infrared spectra of PTFE and PTFE/polyacrylate particles. The core-shell structure of the resulting PTFE/polyacrylate nanocomposite particles was investigated by transmission electron microscopy. The water contact angles of the films prepared from PTFE/polyacrylate nanocomposite particles showed that the films were hydrophilic, which confirmed that polyacrylate covered the surface of the PTFE particles. This kind of PTFE/polyacrylate core-shell nanoparticles might advance the compatibility of PTFE with other materials due to the covering of the polyacrylate shell on the surface of PTFE, which would make them promising in various fields.
Co-reporter:Xuejun Cui, Shuangling Zhong, Hongyan Wang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2007 Volume 303(Issue 3) pp:173-178
Publication Date(Web):15 August 2007
DOI:10.1016/j.colsurfa.2007.03.037
Core–shell fluorine-containing polyacrylate latex particles with fluorine-containing polymer rich in shell were successfully prepared by emulsifier-free seeded emulsion polymerization of fluorine-containing acrylate and fluorine-free acrylate monomers in water with PMMA particles as seeds. The chemical composition and core–shell structure were investigated by Fourier transform infrared (FTIR) spectrometry and transmission electron microscopy (TEM), respectively. TEM, scanning electron microscopy (SEM) and dynamic light scattering (DLS) analysis indicated that the core–shell particles were uniform and possessed narrow size distributions. X-ray photoelectron spectroscopy (XPS) analysis revealed that a gradient concentration of fluorine excited in the structure of the core–shell fluorine-containing latex film from the film–air interface to the film–glass interface. In addition, compared with the latex film of core–shell fluorine-free polyacrylate prepared under the similar polymerization condition, the core–shell fluorine-containing latex film showed higher contact angle and thermal stability.
Co-reporter:Zhengxia Chen;Qiang Gu;Haifeng Zou;Tianqi Zhao
Journal of Polymer Science Part B: Polymer Physics 2007 Volume 45(Issue 8) pp:884-891
Publication Date(Web):1 MAR 2007
DOI:10.1002/polb.21125
Molecular dynamics simulations were applied to investigate the diffusion behaviors of water molecules at temperatures ranging from 323 to 443 K inside amorphous polyacrylate. The results showed that the simulated diffusion coefficients and activation energies were similar to those of experiments. Moreover, the activation energy of water molecules at high temperatures was higher than that at low temperatures by 3.16 kcal mol−1, which was close to the hydrogen-bonding energy between water and polyacrylate. An analysis of the experimental desorption curves of water molecules and their activation energies has confirmed that there are two forms of water molecules inside rubbery polyacrylate, namely, free water and bound water. In addition, it has been concluded that bound water molecules move from one polar group of polyacrylate to another, and this is followed by occasional jumps. Simulated information is very helpful in designing new polyacrylate latex systems and optimizing existent polyacrylate systems. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 884–891, 2007
Co-reporter:Zhengxia Chen;Wenyong Jiang;Xuejun Cui;Xiuli Cheng
Journal of Applied Polymer Science 2006 Volume 99(Issue 2) pp:558-562
Publication Date(Web):28 OCT 2005
DOI:10.1002/app.22490
A novel method to produce fluorine-containing polyacrylate emulsion is presented. It is prepared by the copolymerization of n-methyl methacrylate, n-styrene, n-butyl acrylate, and α-methacrylic acid in the presence of swollen particles of PTFE. The structure and properties of the polymers are characterized by GPC, PSD, SEM, and XPS. The number-average molar mass (Mn) 51,332, and the polydispersity 5.8688 are obtained. The mean diameter of latex particles is 300nm. Scanning electron microscopy reveals that particles of the emulsion are well dispersed. Meanwhile, the F1S content of the surface on the latex membrane is 8.99%. It is shown that the method of mixing micron and nanometer-sized particles should be made the next step of research. It is also proved that inertia polymers can be used in emulsion property modification. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 558–562, 2006
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