Co-reporter:Mingjie Yin, Bobo Gu, Jinwen Qian, A. Ping Zhang, Quanfu An and Sailing He
Analytical Methods 2012 vol. 4(Issue 5) pp:1292-1297
Publication Date(Web):22 Mar 2012
DOI:10.1039/C2AY05791C
A novel type of fiber-optic mercury ion (Hg2+) sensor was prepared by coating poly (N-ethyl-4-vinylpyridinium chloride) (P4VP·HCl) and poly (sodium-p-styrenesulfonate) (PSS) ultrathin film on the surface of a thin-core fiber modal interferometer (TCFMI) with layer-by-layer (LbL) electrostatic self-assembly method. The fabricated TCFMI Hg2+ sensor exhibits a high selectivity to Hg2+ and its detection limit and response time are 10−9 M and 30 s, respectively. The LbL electrostatic self-assembly process is monitored with a quartz crystal microbalance (QCM) and UV–vis spectroscopy for film growth. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) were used to characterize the morphology of the ultrathin film. Both demonstrated nanoporous film, which is helpful in shortening the response time of the TCFMI Hg2+ sensor.
Co-reporter:Zhangliang Gui, Binyang Du, Jinwen Qian, Quanfu An, Qiang Zhao
Journal of Colloid and Interface Science 2011 Volume 353(Issue 1) pp:98-106
Publication Date(Web):1 January 2011
DOI:10.1016/j.jcis.2010.09.026
The influences of pH and NaCl concentration of dipping solutions and the pH and NaCl concentration of disintegration solutions on the disintegration behaviors of poly(4-vinylpyridiniomethanecarboxylate) (PVPMC)/poly(sodium 4-styrenesulfonate) (PSS) (PVPMC/PSS) multilayer films were investigated by ultraviolet–visible spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FT-IR), quartz crystal microbalance (QCM) and atomic force microscopy (AFM). It was found that the disintegration rates and degrees of PVPMC/PSS multilayer films in neutral water could be well controlled by changing pH of dipping solutions and immersion time during the disintegration process. Furthermore, PVPMC/PSS multilayer films could be disintegrated completely and rapidly in pH 8 alkali solution or physiological condition (i.e., 0.15 M NaCl solution). The controllable disintegration of PVPMC/PSS multilayer films was then utilized to fabricate PEC/PSS free-standing multilayer films, in which PEC was a positively charged polyelectrolyte complex made from excessive poly(diallyldimethylammonium) (PDDA) and PSS. The experimental results indicated that the disintegration rates of PVPMC/PSS sacrificial sublayer strongly affected the integrity of the resultant PEC/PSS free-standing multilayer films. Only free-floating PEC/PSS was released from neutral water by disintegrating PVPMC/PSS multilayer sublayers. However, large size flat and tube-like PEC/PSS free-standing multilayer films with good mechanical properties were obtained facilely from pH 8 alkali solution and 0.15 M NaCl solution, respectively. The preparation of such free-standing films at physiological condition may be useful in the biological or medical application.Graphical abstractControllable disintegration of polycarboxybetaine multilayer films (PVPMC/PSS) and fabrication of tube-like free-floating films from normal saline solution.Research highlights► The disintegration rate and degree of PVPMC/PSS multilayer films can be well controlled. ► PVPMC/PSS multilayer films could be completely disintegrated in neutral water within 30 min. ► PVPMC/PSS multilayer films could be rapidly disintegrated in pH 8 alkali solution or 0.15 M NaCl aqueous solution within 2 min. ► Large size flat and tube-like PEC/PSS free-standing multilayer films with good mechanical properties were successfully prepared from 0.15 M NaCl aqueous solution.
Co-reporter:Meihua Zhu, Jinwen Qian, Qiang Zhao, Quanfu An, Yihu Song, Qiang Zheng
Journal of Membrane Science 2011 378(1–2) pp: 233-242
Publication Date(Web):
DOI:10.1016/j.memsci.2011.05.007
Co-reporter:Yanxing Liu, Meihua Zhu, Qiang Zhao, Quanfu An, Jinwen Qian, Kueirrarn Lee, Juinyih Lai
Journal of Membrane Science 2011 s 385–386() pp: 132-140
Publication Date(Web):
DOI:10.1016/j.memsci.2011.09.033
Co-reporter:Zhangliang Gui, Jinwen Qian, Mingjie Yin, Quanfu An, Bobo Gu and Aping Zhang
Journal of Materials Chemistry A 2010 vol. 20(Issue 36) pp:7754-7760
Publication Date(Web):03 Aug 2010
DOI:10.1039/C0JM01476A
Three-component multilayer films were prepared by consecutively depositing a polycation blend of poly(4-vinylpyridiniomethanecarboxylate) (PVPMC) and poly(diallyldimethylammonium) (PDDA) with poly(acrylic acid) (PAA). The self-assembly and disintegration behavior of the multilayer films were investigated in details by UV-vis absorption spectroscopy, quartz crystal microbalance (QCM) and atomic force microscopy (AFM). It was found that nanoporous PDDA/PAA multilayer films can be obtained conveniently by partly disintegrating (PVPMC + PDDA)/PAA multilayer films in a 0.15 M NaCl solution. A novel fast response fiber-optic pH sensor was successfully prepared by constructing nanoporous self-assembly multilayer films on the thin-core fiber interferometer (TCFMI) surface. The response time of a fiber-optic pH sensor deposited with nanoporous PDDA/PAA multilayer film (20 s rise time (tr) and 15 s fall time (tf)) was only one-tenth of that with the nonporous PDDA/PAA multilayer film (240 s and 160 s for tr and tf).
Co-reporter:Zhangliang Gui, Jinwen Qian, Quanfu An, Qiang Zhao, Huangtao Jin and Binyang Du
Journal of Materials Chemistry A 2010 vol. 20(Issue 8) pp:1467-1474
Publication Date(Web):24 Dec 2009
DOI:10.1039/B918170A
The self-assembly and disintegration behavior of polyzwitterion, poly(4-vinylpyridiniomethanecarboxylate) (PVPMC), and negatively charged polyelectrolyte, poly(acrylic acid) (PAA), layer-by-layer (LbL) multilayer films were investigated in detail by using UV-vis absorption spectroscopy, quartz crystal microbalance (QCM) and atomic force microscopy (AFM). The results indicated that the PVPMC/PAA multilayer films grew linearly with increasing bilayer number. The disintegration rate of PVPMC/PAA multilayers could be well controlled by varying the concentration of salt in aqueous solution. It was found that PVPMC/PAA multilayer films could be completely disintegrated in 0.9% normal saline solution within 15 min. Such controllable disintegration behavior rendered the PVPMC/PAA multilayer as an excellent sacrificial sublayer for fabricating free-standing LbL multilayer films. Free-standing multilayer films were then successfully fabricated by LbL self-assembly of positively charged polyelectrolyte complex (PEC), made from poly(diallyldimethylammonium) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS), and negatively charged PSS with PVPMC/PAA as a sacrificial sublayer, which was disintegrated in 0.9% normal saline solution. The obtained free-standing films had good mechanical properties with 24.1 MPa tensile strength at break and 0.56 GPa Young's modulus.
Co-reporter:Huangtao Jin, Quanfu An, Qiang Zhao, Jinwen Qian, Meihua Zhu
Journal of Membrane Science 2010 Volume 347(1–2) pp:183-192
Publication Date(Web):1 February 2010
DOI:10.1016/j.memsci.2009.10.023
Poly (N-ethyl-4-vinylpyridiniumbromide) (PEVP) was synthesized by the reaction between poly (4-vinylpyridine) (P4VP) and ethyl bromide, and polyelectrolyte complexes (PECs) based on PEVP and sodium carboxymethyl cellulose (CMCNa) were prepared in HCl aqueous solutions. The ionic complexation degrees (ICD) of PECs can be effectively controlled by tuning either quaternization degree (QD) of PEVP polycation or carboxylate group (–COO–) content on CMCNa polyanion, which was characterized by elemental analysis (EA) and Fourier transform infrared (FT-IR). The dilute solution viscosity behavior of PECs was investigated by Ubbelohde viscometer. The hydrophilicity and surface morphologies of polyelectrolyte complex membranes (PECMs) were examined by contact angle meter and field emission scanning electron microscopy (FESEM), respectively. The PECMs were subjected to dehydration of ethanol and showed very high separation performance. Interestingly, the permeation flux of PECMs increased while water content in permeate decreased with increasing ICD. The performance was discussed in terms of the unique structural characteristics of PEVP, PECs and PECMs.
Co-reporter:Mingjie Yin, Jinwen Qian, Quanfu An, Qiang Zhao, Zhangliang Gui, Jing Li
Journal of Membrane Science 2010 Volume 358(1–2) pp:43-50
Publication Date(Web):15 August 2010
DOI:10.1016/j.memsci.2010.04.025
Polyelectrolytes layer-by-layer (LbL) self-assembly multilayer films are mostly built up statically till now. In this work, positively charged poly(diallyldimethylammonium chloride) (PDDA) and negatively charged poly(sodium-p-styrenesulfonate) (PSS) LbL multilayer films were built up at vibration condition. The absorption and the thickness growth of multilayers were monitered by UV–vis spectrum and quartz crystal microbalance (QCM). The root mean square (RMS) surface roughness and morphology evolution of films were characterized by atomic force microscopy (AFM). LbL multilayer films, deposited on modified polyamide (MPA) reverse osmosis membrane, were subjected to pervaporation dehydration of water–isopropanol mixture. Vibration affects the UV–vis absorption amount and the thickness of the multilayer film, but it does not alter the film growth rule in presence or absence of added salt. Multilayer films built up at the vibration condition show higher selectivity with high permeation flux. This is attributed to the fact that the chains deposited orderly and the films formed are dense and smooth at the vibration condition.
Co-reporter:Meihua Zhu, Jinwen Qian, Qiang Zhao, Quanfu An, Jing Li
Journal of Membrane Science 2010 Volume 361(1–2) pp:182-190
Publication Date(Web):30 September 2010
DOI:10.1016/j.memsci.2010.05.058
Poly(diallyldimethylammonium chloride) (PDDA)/sodium polyacrylate (PAANa) polyelectrolyte complex (PEC) was fabricated by adding PDDA dilute aqueous solution dropwise into PAANa dilute aqueous solution with 0.007 M HCl. PEC/PVA(polyvinyl alcohol) blend liquids and their blend membranes were prepared by two blend methods of (a) PVA-solution/PEC-solution blending commonly used and (b) PVA-solid/PEC-solution blending proposed. Both blend liquids obtained were studied by viscometry and particle size analysis meter. Surface morphologies of PEC/PVA blend membranes cast from blend liquids were characterized by atomic force microscopy (AFM) and field emission scanning electron microscope (FESEM). Dynamic water contact angle and equilibrium swelling degree (ESD) of blend membranes in water–isopropanol feed were measured. Pervaporation (PV) dehydration of blend membranes for water–isopropanol feed was investigated. It was found that the structure and property of blend liquids, the surface property and ESD of blend membranes prepared by (b) are quite different from those prepared by (a). The stability and PV performance of PEC/PVA blend membranes prepared by (b) is much better than that prepared by (a). It is attributed to the preparation methods, which led to the difference in the interaction in blend liquids and the transition of fluid property and finally the change of the compatibility between PEC and PVA in blend membranes.
Co-reporter:Qiang Zhao, Jinwen Qian, Quanfu An, Zhiwei Sun
Journal of Membrane Science 2010 Volume 346(Issue 2) pp:335-343
Publication Date(Web):15 January 2010
DOI:10.1016/j.memsci.2009.09.055
Two negatively charged polyelectrolyte complex colloidal nanoparticles (PEC−) and one positively charged nanoparticle (PEC+) were prepared and used as novel layer-by-layer (LbL) building blocks. These PEC nanoparticles include poly(2-methacryloyloxy ethyl trimethylammonium chloride)/sodium carboxymethyl cellulose (PDMC/CMCNa PEC−), poly(diallyldimethylammonium chloride)/CMCNa (PDDA/CMCNa PEC−) and PDDA/poly(sodium-p-styrenesulfonate) (PDDA/PSS PEC+). LbL multilayer films based on (PEC+/PEC−) were constructed on both quartz slides and modified polyamide (MPA) reverse osmosis support membranes. UV–vis spectroscopy, quartz crystal microbalance (QCM), field emission scanning microscopy (FESEM) and atomic force microscopy (AFM) were utilized to follow the thickness growth and morphology evolution of these multilayer films with increasing bi-layer numbers. LbL multilayer films deposited on MPA support membranes were subjected to pervaporation dehydration of 10 wt% water–isopropanol and effect of bi-layer numbers and feed temperature on pervaporation performance was studied. Generally, PEC+/PEC− can be LbL self-assembled successfully on both substrates with a thickness growth rate ca. 200 nm/bi-layer. Moreover, PEC+/PEC− multilayer films show high pervaporation performance with film thickness up to several micrometers. For example, performance of the multilayer films in dehydrating 10 wt% water–isopropanol at 50 °C is J = 1.18 kg/m2 h, α = 1013 for (PEC+/PDMC-CMCNa PEC−)24 and J = 1.36 kg/m2 h, α = 938 for (PEC+/PDMC-CMCNa PEC−)25, respectively.
Co-reporter:Qiang Zhao, Jinwen Qian, Zhangliang Gui, Quanfu An and Meihua Zhu
Soft Matter 2010 vol. 6(Issue 6) pp:1129-1137
Publication Date(Web):08 Jan 2010
DOI:10.1039/B918529A
A two-step procedure was adopted to prepare cellulose-based polyelectrolyte complexes (PECs) nanoparticles dispersed in water. First, an aqueous solution of a weak anionic polyelectrolyte of sodium carboxymethyl cellulose (CMCNa) was mixed with four types of cationic polyelectrolytes (poly 2-methacryloyloxy ethyl trimethylammonium chloride (PDMC), cationic cellulose, poly diallyldimethylammonium chloride (PDDA), chitosan (CS)) in HCl aqueous solutions. Four types of CMCNa-based PEC solids (CMCNa-PDMC, CMCNa-cationic cellulose, CMCNa-PDDA and CMCNa-CS), were obtained, purified and dried. Second, these PECs were re-dispersed in NaOH aqueous solutions. PEC solids and their aqueous dispersions were characterized by FT-IR, wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC) and dynamic light scattering (DLS), respectively. It was found that well grown fractal patterns (referred to as fractal “trees”) with diameters ranging from 5–300 μm for the four PECs were obtained after their aqueous dispersions were dried on silicon wafers or glass slides at 30 °C. This PECs interfacial self-assembly phenomenon is interesting but not shown in literature, even though various other PECs dispersions have also been dried in the similar way. Fractal dimensions of these fractal “trees” were calculated and their structures were characterized by polarized light microscopy (PLM), filed emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). The formation mechanism of these fractal “trees” was tentatively examined by time-dependent FESEM. Moreover, effects of drying temperature, PEC concentration and solvent composition on fractal “trees” formation were studied. Potential applications of the fractal pattern formation in fields such as fast bottom-up nanofabrication, surface patterning and membrane separation were discussed.
Co-reporter:Z. L. Gui;J. W. Qian;X. K. Li;B. Q. Zheng;Q. F. An
Journal of Applied Polymer Science 2010 Volume 117( Issue 5) pp:2915-2922
Publication Date(Web):
DOI:10.1002/app.32193
Abstract
Effects of external conditions, solution concentration, solvent quality, added salt, and pH on the chain conformation dimension of two kinds of polyacrylamide (PAAm) flocculants, neutral-PAAm, and cationic-P(AAm-DMC) (DMC, 2-[(methacryloyloxy)ethyl] trimethylammonium chloride), in parent solutions and their flocculation performance for Kaolin suspensions have been investigated by Ubbelohde viscometer and spectrophotometer, respectively. It was found that a negative correlation existed between the flocculation performance of PAAm flocculants and their chain sizes in parent solutions. This was attributed to the expanded chain deformation of PAAm flocculants during the flocculation process from the flocculant parent solution to the Kaolin suspension and was interpreted in term of the competitive interaction among the polymeric flocculant, solvent, and Kaolin particle in the chain deformation process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010
Co-reporter:Qiang Zhao, Jinwen Qian, Quanfu An and Binyang Du
Journal of Materials Chemistry A 2009 vol. 19(Issue 44) pp:8448-8455
Publication Date(Web):05 Oct 2009
DOI:10.1039/B911386J
A novel method for speedy fabrication of free-standing layer-by-layer (LbL) multilayer films in salt free media, and without the need for a sacrificial sublayer is described by using two different polyelectrolyte complex (PEC) nanoparticles as LbL self-assembly building blocks. Negatively charged polyelectrolyte complex particles (PEC−) consisting of poly(diallyldimethylammonium chloride)/sodium carboxymethyl cellulose (PDDA/CMCNa), and positively charged polyelectrolyte complex particles (PEC+) consisting of PDDA/poly(sodium-p-styrenesulfonate) (PDDA/PSSNa) were prepared and characterized by FT-IR, zeta-potential (ζ potential) and transmission electron microscopy (TEM). The LbL self-assembly of PEC+/PEC− and PDDA/PEC− was followed by quartz crystal microbalance (QCM), optical transmittance, UV-vis absorption spectroscopy and atomic force microscopy (AFM). QCM results show that the thickness growth rate of the PEC+/PEC− pair is 9 times faster than that of the PDDA/PEC− pair and this result is also supported by optical transmittance and UV-vis absorption. A robust free-standing multilayer film of (PEC+/PEC−)25 can be easily peeled off from the substrate after being cross-linked in 3.5 wt% glutaraldehyde (GA) (80 °C, 50mins). Field emission electron scanning microscopy (FESEM) indicates that both the surface and cross-section of the multilayer film display layered structures. Furthermore, multiwall carbon nanotubes (MWCNTs) can also be uniformly incorporated into the free-standing LbL multilayer film by pre-incorporating MWCNTs into PEC− particles. The experimental results show that using oppositely charged PEC particles as LbL assembly components is a speedy and convenient method to fabricate free-standing LbL multilayer films either with or without nanofillers.
Co-reporter:Qiang Zhao, Jinwen Qian, Meihua Zhu and Quanfu An
Journal of Materials Chemistry A 2009 vol. 19(Issue 46) pp:8732-8740
Publication Date(Web):14 Oct 2009
DOI:10.1039/B912578G
Polyelectrolyte–polyelectrolyte complexes/multiwall carbon nanotubes (PECs/MWCNTs) nanocomposites have not been prepared until now because PECs are generally insoluble and infusible. In this work, solution-processable PEC/MWCNT nanocomposites and their membranes were prepared by in situ incorporation of MWCNTs into bulk PECs. The ionic complexation between poly(diallyldimethylammonium chloride) (PDDA) and sodium carboxymethyl cellulose (CMCNa) in the presence of MWCNTs was followed by ζ potential and optical transmittance measurements. Structures of PEC/MWCNT nanocomposites were characterized by FT-IR, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). It is found that MWCNTs are encapsulated by a layer of PEC and dispersed in a PEC matrix mainly on a single nanotube level. Mechanical properties of the nanocomposite membrane loaded with 7 wt% MWCNTs are greatly improved, showing 2.6 times higher tensile strength and 1.8 times higher modulus as compared with that of the pristine PEC. PEC/MWCNT nanocomposite membranes also display very high performance in pervaporation dehydration of isopropanol. This high pervaporation performance is reproducible with cycling feed temperatures and stable with increasing operation time up to 20 days.
Co-reporter:Qiang Zhao Jinwen Qian, Quanfu An, Qian Yang and Zhangliang Gui
ACS Applied Materials & Interfaces 2009 Volume 1(Issue 1) pp:90
Publication Date(Web):November 24, 2008
DOI:10.1021/am800037v
Solution-processable polyelectrolyte complexes (PECs) between poly(diallyldimethylammonium chloride) (PDDA) and poly(acrylic acid) (PAA) were synthesized in aqueous NaOH and obtained in their solid forms by protection and deprotection of carboxylic acid groups. Elemental analysis, conductance measurement, and FT-IR showed that the composition and ionic complexation degree (ICD) of the PECs can be controlled effectively by tuning the NaOH concentration in both parent polyelectrolyte solutions. Thermal gravity analysis showed that PECs revealed good thermal stability, and differential scanning calorimetry showed that the glass transition temperature (Tg) of PECs increased with increasing ICD and finally became undetectable when ICD was above 0.16. Viscosity properties of the PEC solutions were well correlated to the ICD of PECs, and it was found that solid PECs could be redissolved in dilute NaOH without breaking the ionic complexation between PDDA and PAA. Homogeneous PEC membranes (HPECMs) were made from their concentrated solutions, and their morphologies were examined by field emission scanning electron microscopy. These novel HPECMs were subjected to dehydration of organics for the first time, and a very promising performance was obtained. Furthermore, another two solution-processable PECs between weak anionic polyelectrolyte and cationic polyelectrolyte were also synthesized by the same method and showed a very high separation performance.Keywords: pervaporation; polyelectrolyte complex membrane; thermal property; viscosity property
Co-reporter:Qiang Zhao, Jinwen Qian, Quanfu An, Zhangliang Gui, Huangtao Jin, Minjie Yin
Journal of Membrane Science 2009 Volume 329(1–2) pp:175-182
Publication Date(Web):5 March 2009
DOI:10.1016/j.memsci.2008.12.031
Polyelectrolyte complexes (PECs) between poly(diallyldimethylammonium chloride) (PDDA) and sodium carboxymethyl cellulose (CMCNa) with four ionic complexation degrees (ICD) were synthesized and their homogeneous polyelectrolyte complex membranes (HPECMs) were fabricated. Elemental analysis and FT-IR were used to determine the composition and chemical structure of PECs. Thermogravimetric analysis (TGA), wide-angle X-ray diffraction (WAXD) and viscometry were used to characterize the thermal stability, crystallinity and solution properties of PECs, respectively. Field emission scanning electron microscope (FESEM) was used to examine the surface morphology of HPECMs, which were subjected to the pervaporation dehydration of isopropanol. Effects of membrane fabrication methods, cycling of feed temperature and ICD of PECs on pervaporation performance of HPECMs are discussed. Meanwhile, HPECMs were also subjected to dehydration of three other organics and showed very good performance. All these performances are explained in terms of the unique structural characteristics of PECs and HPECMs.
Co-reporter:Peng Zhang, Jinwen Qian, Quanfu An, Xiaoqing Liu, Qiang Zhao, Huangtao Jin
Journal of Membrane Science 2009 Volume 328(1–2) pp:141-147
Publication Date(Web):20 February 2009
DOI:10.1016/j.memsci.2008.11.049
Polyethylenimine/poly(acrylic acid sodium salt) (PEI/PAA) ultrathin polyelectrolyte multilayer membranes were fabricated by an electric field enhanced method and were used for isopropanol/water pervaporation. Surface properties of the electric field enhanced multilayer polyelectrolyte membranes (EPEMs) prepared under different conditions were investigated by atomic force microscopy (AFM) and contact angle (CA) measurements. It was found that surface properties (roughness and hydrophilicity) of EPEMs strongly depend on the direction of the electric field, dipping time, applied voltage, number of bilayers, which, in turn, affect their pervaporation performance. The (PEI/PAA)4PEI EPEMs fabricated with a dipping time of 15 min and an applied voltage of 5 V for separating 10 wt% water–isopropanol mixtures exhibited high separation factor and large flux. Meanwhile, the performance of the EPEMs displays good storage stability within 60 days.
Co-reporter:Qiang Zhao, Jinwen Qian, Chenxiao Zhu, Quanfu An, Tianqiang Xu, Qiang Zheng, Yihu Song
Journal of Membrane Science 2009 Volume 345(1–2) pp:233-241
Publication Date(Web):1 December 2009
DOI:10.1016/j.memsci.2009.09.003
Polyelectrolyte complexes (PECs) nanohybrid membranes prepared via traditional methods have not been reported due to the insolubility and infusibility of PECs. In this study, a novel method for fabricating PEC-based nanohybrid membranes filled with both SiO2 (globule) and multiwall carbon nanotubes (MWCNTs, linear) is proposed. Five types of PEC/SiO2 nanohybrids were prepared and the incorporation of SiO2 nanoparticles into PEC matrixes was followed by ζ potential and optical transmittance. Structures of PEC/SiO2 nanohybrids were characterized by FT-IR, transmission electron microscopy (TEM) and field emission electron scanning microscopy (FESEM). SiO2 is proved to be uniformly dispersed in PEC matrix at single nanoparticles level. Importantly, the incorporation of SiO2 enhances the processability of pristine PECs, i.e., some insoluble PECs turn soluble in NaOH after the incorporation of SiO2 nanoparticles. Mechanical properties of CMCNa–PDDA PEC/SiO2 nanohybrid membranes are improved and five PEC/SiO2 nanohybrid membranes all show high pervaporation performance in isopropanol dehydration. Moreover, PEC/MWCNTs nanohybrid films were prepared in the same method and FESEM shows that MWCNTs are evenly dispersed in the PEC matrix mainly at a single MWCNT level. Note that the fine dispersion of both SiO2 and MWCNTs in PEC matrix cannot be achieved by direct blending PEC with SiO2 or MWCNTs.
Co-reporter:Qiang Zhao, Jinwen Qian, Quanfu An, Congjie Gao, Zhangliang Gui, Huangtao Jin
Journal of Membrane Science 2009 Volume 333(1–2) pp:68-78
Publication Date(Web):1 May 2009
DOI:10.1016/j.memsci.2009.02.001
Soluble polyelectrolyte complexes (PECs) between chitosan (CS) and sodium carboxymethyl cellulose (CMCNa) were synthesized in aqueous hydrochloric acid (HCl) and obtained in their solid form. FT-IR, elemental analysis (EA), thermal gravity analysis (TGA), wide-angle X-ray diffraction (WAXD), and viscometry were used to characterize the chemical structure, composition, thermal stability, crystallinity and solution property of PECs, respectively. These PECs could be dissolved in aqueous NaOH and their homogeneous polyelectrolyte complex membranes (HPECMs) were made by solution casting method. Both the surface morphology of HPECMs and the morphology of single PEC aggregate were examined by field emission scanning electron microscope (FESEM), and atomic force microscopy (AFM). Effects of the water content in aqueous ethanol and temperature on the swelling behavior and pervaporation dehydration of HPECM were examined. A good performance of J = 1.14 kg/m2 h, α = 1062 was obtained with HPECM0.25 in dehydrating 10 wt.% water–ethanol at 70 °C. The swelling behavior and pervaporation performance were interpreted in terms of structure characteristics of both PECs and HPECMs.
Co-reporter:Qiang Zhao, Jinwen Qian, Quanfu An, Meihua Zhu, Minjie Yin, Zhiwei Sun
Journal of Membrane Science 2009 Volume 343(1–2) pp:53-61
Publication Date(Web):1 November 2009
DOI:10.1016/j.memsci.2009.07.009
Poly(vinyl alcohol) (PVA) was blended with soluble polyelectrolyte complex (PEC) made from poly(diallyldimethylammonium chloride) (PDDA) and sodium carboxymethyl cellulose (CMCNa). Crystallinity, thermal transition, and thermal stability of the PVA/PEC blends were characterized by using wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), and thermal gravity analysis (TGA), respectively. Surface morphology, cross-section and phase structure of the blend membranes were examined by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). Surface hydrophilicity and swelling behavior of the blend membranes were examined by water contact angle (CA) and swelling tests. Blend membranes were subjected to isopropanol dehydration, and effects of blend composition, feed composition and feed temperature on pervaporation performance are discussed in terms of phase structures of blend membranes. A performance of J = 1.35 kg/m2 h, α = 1002, was obtained for blend membrane containing 50 wt% PEC in dehydrating 10 wt% water–isopropanol at 70 °C.
Co-reporter:Zhangliang Gui, Jinwen Qian, Quanfu An, Hong Xu, Qiang Zhao
European Polymer Journal 2009 Volume 45(Issue 5) pp:1403-1411
Publication Date(Web):May 2009
DOI:10.1016/j.eurpolymj.2009.02.010
A novel zwitterionic polyacrylamide AMVPPS copolymer containing sulfobetaine groups was synthesized by copolymerizing acrylamide (AM) and 4-vinylpyridine propylsulfobetaine (4-VPPS) in 0.5 mol/L NaCl solution with potassium persulfate (K2S2O8) and sodium bisulfite (NaHSO3) as initiator. The structure and composition of AMVPPS copolymer were characterized by FT-IR spectroscopy, 1H NMR and elemental analyses. Thermal stability and solution properties of AMVPPS copolymer were studied by thermogravimetry analysis (TGA) and viscometry. Anti-polyelectrolyte behavior was observed and was found to be enhanced with increasing 4-VPPS content in copolymer. The flocculation performance for 2.5 g/L kaolin suspension and 2.5 g/L hematite suspension was evaluated by transmittance measurement and phase contrast microscopy. The effects of 4-VPPS content in the copolymer, intrinsic viscosity and the added salt on the flocculation performance were investigated. It was found that AMVPPS copolymer was a good flocculant for both anionic kaolin and cationic hematite suspensions and the flocculation performance of copolymer was much better than that of pure polyacrylamide (PAM). A very wide range of the optimum flocculation concentration, named as “flocculation window”, was found for both suspensions. These flocculation characteristics were mainly dependent on the charge neutralization, the intragroup conformation transition from water to NaCl solution and then the interchain bridging of the zwitterionic AMVPPS copolymer.
Co-reporter:Qiang Zhao, Jinwen Qian, Quanfu An, Zhihui Zhu, Peng Zhang, Yunxiang Bai
Journal of Membrane Science 2008 Volume 311(1–2) pp:284-293
Publication Date(Web):20 March 2008
DOI:10.1016/j.memsci.2007.12.023
A novel polyacrylonitrile–b-poly(ethylene glycol)–b-polyacrylonitrile (PAN–b-PEG–b-PAN) block copolymer was synthesized by water-phase precipitation copolymerization, using ceric ammonium nitrate–PEG pair as an initiator. Structure and composition of the block copolymer were characterized by FT-IR, 1H NMR, differential scanning calorimetry and elemental analysis. Block copolymer membranes were prepared by solution casting method and morphologies of the membranes were examined by transmission electron micrographs. Dehydration of aqueous acetone solution with 5 wt% water is considerably improved by using block copolymer membrane and pervaporation performance is greatly dependent on the PEG molecular weight (MPEG) and weight content (WPEG) in the block copolymer. Maximum separation factor and minimum permeate flux displayed for the block copolymer membrane with MPEG = 6000 and WPEG = 7.3 wt%. Effect of feed temperature and feed composition on pervaporation was analyzed in two pairs of parameters, separation factor, flux and selectivity, permeability and it was found that the latter pair can better correlate pervaporation performance with membrane structure. These pervaporation characteristics of the membrane were explained mainly in terms of PEG micro-phase separation behavior in the PAN–b-PEG–b-PAN block copolymer and PEG solubility characteristics in water with temperature.
Co-reporter:Yunxiang Bai, Jinwen Qian, Chunfang Zhang, Lin Zhang, Quanfu An, Huanlin Chen
Journal of Membrane Science 2008 Volume 325(Issue 2) pp:932-939
Publication Date(Web):1 December 2008
DOI:10.1016/j.memsci.2008.09.019
Cross-linked hydroxy terminated polybutadiene (HTPB)-based polyurethaneurea (PU), HTPB–DVB–PU, was synthesized by a three-step polymerization process. It was firstly used as membrane material to recover aroma, ethyl acetate (EA), from aqueous solution by pervaporation (PV). The effects of the content of cross-linker DVB, EA concentration in feed, and operating temperature on the PV performance of HTPB–DVB–PU membranes were investigated. The membranes demonstrated high EA permselectivity as well as high total flux. The introduction of DVB significantly enhanced the temperature resistance ability of the HTPB–DVB–PU membranes. With increasing DVB content, the separation factor increased while the total flux decreased a little. The best PV performance, separation factor and total flux were 655 and 256 g/m2 h, respectively with feed concentration of 2.5 wt% EA at 30 °C. These PV performances with increasing DVB content were explained in terms of the viewpoint of chemical compositions and physical structures of the HTPB–DVB–PU membranes.
Co-reporter:Quan Fu An, Jin Wen Qian, Qiang Zhao, Cong Jie Gao
Journal of Membrane Science 2008 Volume 313(1–2) pp:60-67
Publication Date(Web):10 April 2008
DOI:10.1016/j.memsci.2007.12.073
The composition effect of polyacrylonitrile-block-poly(methyl acrylate) (P(AN-b-MA)) block copolymer on the swelling behavior and the pervaporation performance of the resultant membranes were investigated for separating benzene/cyclohexane mixtures. It was found that the degree of swelling (DS) of membranes increased with increasing the MA content in P(AN-b-MA) block copolymer and the benzene content in feed at 30 °C. The results also showed that the benzene flux (Jbenzene) of P(AN-b-MA) membranes increased and separation factor (α) decreased with increasing MA content in the membrane, the benzene content in feed, and the feed temperature. Further, the dependence of the swelling behavior and pervaporation performance on the MA content in the membranes revealed a discontinuity phenomenon. The DS and the benzene flux increased dramatically when the MA content in the membrane exceeded 40 mol%. Also, P(AN-b-MA) block copolymer membranes with less or more than 40 mol% MA content revealed different surface morphologies from both scanning electron microscopy (SEM) images and atomic force microscopy (AFM). All these might be explained by the transition of MA segment from a dispersion phase to a continuous phase with increasing MA content in the P(AN-b-MA) block copolymer membranes.
Co-reporter:Peng Zhang, Jin-wen Qian, Yang Yang, Yun-Xiang Bai, Quan-Fu An, Wei-dong Yan
Journal of Membrane Science 2007 Volume 288(1–2) pp:280-289
Publication Date(Web):1 February 2007
DOI:10.1016/j.memsci.2006.11.025
Palygorskite–polyacrylamide (PGS–PAM) hybrid materials were synthesized via intercalation polymerization initiated by redox initiator consisting of modified PGS (reducer) and ceric salt Ce4+ (oxidant), and used as pervaporation membranes. The swelling behavior of hybrid membranes was investigated in single xylene isomer (p-xylene, m-xylene and o-xylene), binary xylene isomer mixtures (p-/o-xylene (the mixtures of p- and o-xylene), o-/m-xylene (the mixtures of o- and m-oxylene) and p-/m-xylene (the mixtures of p- and m-xylene)) and ternary isomer mixture (p-/m-/o-xylene (the mixtures of p-, m- and o-xylene)). A maximum value of degree of swelling at equilibrium (DSequilibrium) in single xylene isomer at 30 °C exhibited for the hybrid membrane with 1.92 wt% PGS. Negative deviation and both negative and positive deviations of the DSequilibrium based on the addition rule existed in binary or ternary xylene isomer mixtures respectively for hybrid membranes with different PGS content at 30 °C. Also, a maximum value of separation factor of the hybrid membrane revealed for each pair of binary xylene isomer mixtures when the PGS content was 1.92 wt% in the hybrid membrane. A reversion of the preferential selectivity and a high permeation activation energy of the hybrid membrane occurred at the concentration region with high p-xylene content in the p-/m-xylene binary xylene isomer mixtures. The swelling behavior and pervaporation performance of PGS–PAM hybrid membranes were discussed in terms of the entrapping channel in the PGS for the potential introduction of xylene isomers, the interaction between xylene isomers in feed and the solution–diffusion mechanism in the pervaporation process.
Co-reporter:Yunxiang Bai, Jinwen Qian, Quanfu An, Zhihui Zhu, Peng Zhang
Journal of Membrane Science 2007 Volume 305(1–2) pp:152-159
Publication Date(Web):15 November 2007
DOI:10.1016/j.memsci.2007.07.042
The degree of crystallization, surface property and density of ethylene–vinyl acetate (EVA) copolymer membranes with different vinyl acetate (VA) content were measured by differential scanning calorimetry (DSC), contact angle meter and pycnometer. The pervaporation (PV) characteristics of the EVA copolymer membranes for recovery of ethyl acetate (EA) from aqueous EA solutions have been investigated. The separation factor (α) decreased with increasing VA content from 26 wt.% (EVA26) to 100 wt.% (poly vinyl acetate, PVAc) in EVA copolymer membranes. A maximum EA flux (JEA,max) of EVA membrane with 38 wt.% VA content revealed for 2.5 wt.% aqueous EA solution at 30 °C, JEA,max reached to 550 g/(m2 h) and α was to 118. These PV characteristics of EVA membranes were explained in terms of the crystallinity of EVA copolymer and the affinities between EA or water and VA segment in EVA copolymer membrane. Experimental results also show that both α and JEA increased with increasing feed temperature and feed concentration.
Co-reporter:Quan Fu An, Jin Wen Qian, Meng Wang, Yin Lu, Phillip Choi
Chinese Chemical Letters 2007 Volume 18(Issue 11) pp:1423-1426
Publication Date(Web):November 2007
DOI:10.1016/j.cclet.2007.09.007
Based on the expression of the index of coil interpenetration (i.e., the degree of coil overlap, ξb) of amorphous polymers in the bulk state proposed by Qian, the ξb was rewritten as ξb=ρb[η]θ/1.66ξb=ρb[η]θ/1.66 via Flory's intrinsic viscosity equation at theta conditions. The ξb of poly (vinyl chloride) (PVC) dense membranes with different molecular weights and cellulose diacetate (CA) dense membranes prepared using different solvents were determined. The permeability, permeation coefficient (P) of nitrogen and permeation flux (J) of liquid through both membranes, respectively, was measured. P and J decreased exponentially with increasing ξb for PVC and CA membranes were revealed.
Co-reporter:B. Q. Zheng;J. W. Qian;X. K. Li;Z. H. Zhu
Journal of Applied Polymer Science 2007 Volume 103(Issue 3) pp:1585-1592
Publication Date(Web):8 NOV 2006
DOI:10.1002/app.25443
Flocculation performance of three kinds of polyacrylamide (PAAm), linear-PAAm, Al(OH)3–PAAm hybrid, and star–PAAm, in kaolin suspensions have been investigated by Spectrophotometer. It was found that the flocculation performance of the polymer flocculant is enhanced at the beginning and then impaired with increasing parent solution concentration (Cp) and an optimal parent solution concentration (Cop) exists, which is directly proportional to both critical concentrations of C* and Cs of the polymer in the dilute aqueous solution, and can be roughly expressed by an empirical formula, Cop = 3.1 × 10−3 + 643.1Cs. The findings suggests that flocculation performance of a given polymer is dependent on both of the interchain association and the chain contact of the polymer chains in the parent solution and in the kaolin suspension, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1585–1592, 2007
Co-reporter:Yunxiang Bai;Jian Yin;Zhibin Zhai;Yang Yang
Journal of Applied Polymer Science 2007 Volume 104(Issue 1) pp:
Publication Date(Web):25 JAN 2007
DOI:10.1002/app.25590
Hydroxyterminated polybutadiene (HTPB)-based polyurethaneurea (PU), HTPB-PU, was synthesized by two-step polymerization and was firstly used as membrane materials to recover aroma, ethyl acetate (EA), from aqueous solution by pervaporation (PV). The effects of the number–average molecular weight (Mn) of HTPB, EA in feed, operating temperature, and membrane thickness on the PV performance of HTPB-PU membranes were investigated. The membranes demonstrated high EA permselectivity as well as high EA flux. The DSC result showed two transition temperatures in the HTPB-PU membrane and contact angle measurements revealed the difference of hydrophobicity of the membrane at both sides, which were induced by glass plate and air, respectively, due to movement of the soft hydrophobic polybutadiene (PB) segments in HTPB-PU chains. Furthermore, the PV performance of the HTPB-PU membrane with the hydrophobic surface facing the feed was much better than that with the hydrophilic surface. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 552–559, 2007
Co-reporter:Minghui Fang;Xiaoqian Qian;Hangbin Jiang;Yunxiang Bai
Polymer Composites 2006 Volume 27(Issue 5) pp:470-474
Publication Date(Web):8 AUG 2006
DOI:10.1002/pc.20214
The polyurethane/C16C18-MMT (the montmorillonite modified with cetyloctadecyldimethyl ammonium bromide) nanocomposites were synthesized by intercalative polymerization and cured under room temperature. The d-spacing and the dispersion of the C16C18-MMT in the nanocomposites were measured by X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM). The mechanical and thermal properties of the nanocomposites were measured by Universal Testing System, Electric Anti-fold Instrument, Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC). It was found out that introducing C16C18-montmorillonite (MMT) in the polyurethane (PU) displayed good mechanical properties and thermal stability. Rheology behavior in liquid state showed that the addition of the C16C18-MMT to PU resulted in low gel time and high viscosity. POLYM. COMPOS. 27:470–474, 2006. © 2006 Society of Plastics Engineers.
Co-reporter:M. H. Fang;X. Q. Qian;W. Y. Yang;X. J. Xiang;J. W. Qian;X. J. Xiang;W. Y. Yang;J. W. Qian;M. H. Fang;X. Q. Qian
Journal of Applied Polymer Science 2006 Volume 100(Issue 6) pp:4333-4337
Publication Date(Web):8 MAR 2006
DOI:10.1002/app.23306
A polyurethane/nanosilica (PU/SiO2) hybrid for grouting was prepared in a two-step polymerization using poly(propylene glycol) diols as the soft segment, toluene 2,4-diisocyanate (TDI) as the diisocyanate, 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA) as the chain extender, and acetone as the solvent. The size and dispersion of nanosilica, the molecular structure, mechanical properties, rheological behavior, thermal performance, and the UV absorbance characteristic of the PU/SiO2 hybrid were investigated by transmission electron microscopy (TEM), FTIR, mechanical tests, viscometry, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and UV spectroscopy. Nanosilica dispersed homogeneously in the PU matrix. The maximum values of mechanical properties such as tensile strength, elongation break, and adhesive strength showed an addition of nanosilica of about 2 wt %. Resistance to both high and low temperatures was better than with PU. And the UV absorbance of the PU/SiO2 hybrid increased in the range of 290–330 nm with increasing nanosilica content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4333–4337, 2006
Co-reporter:Meng Wang;Wuyuan Yang;Baoqing Zheng
Journal of Applied Polymer Science 2006 Volume 101(Issue 3) pp:1494-1500
Publication Date(Web):4 MAY 2006
DOI:10.1002/app.24229
A novel inorganic–organic hybrid with modified palygorskite (MPGS) and acrylamide was prepared with a heterogeneous redox initiator system composed of a reductive agent (MPGS) together with an oxidant (Ce4+). The MPGS–polyacrylamide (PAM) hybrids were characterized by X-ray diffraction, 1H-NMR, Fourier transform infrared spectroscopy, conductometry, viscometry, and size exclusion chromatography. The MPGS–PAM hybrid could be a starlike and ionic bond hybrid. The ionization behavior of the MPGS–PAM hybrid in deionized water depended strongly on its coil dimension and the palygorskite content in the hybrid. The flocculation performance of the MPGS–PAM hybrid in a kaolin suspension was also related to its intrinsic viscosity and the palygorskite content and was better than that of PAM, except for that of the MPGS–PAM hybrid with a high palygorskite content. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1494–1500, 2006
Co-reporter:Yunxiang Bai;Qiang Zhao;Yong Xu;Shengrong Ye
Journal of Applied Polymer Science 2006 Volume 102(Issue 3) pp:2832-2838
Publication Date(Web):23 AUG 2006
DOI:10.1002/app.24557
Aromatic copolyester of poly(trimethylene-co-ethylene terephthalate) (PTET) with different composition was synthesized and the PTET sample with 60% weight fraction of polytrimethylene (PTET-60) was amorphous. The compatibility of PTET-60/cellose acetate (CA) blends and the pervaporation of their membranes for separation of benzene/cyclohexane mixtures were investigated. It was found that PTET-60 is compatible with CA when the weight fraction of PTET-60 in PTET-60/CA blends (WPTET-60) is lower than 0.35 and more than 0.5. Both the degree of swelling (DS) and the permeation flux (J) of these blend membranes increased with increasing WPTET-60 from 0 to 0.35, and a maximum value of the separation factor (α) displayed at WPTET-60 = 0.25. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 102: 2832–2838, 2006
Co-reporter:J. W. Qian;Q. F. An;L. N. Wang;L. Zhang;L. Shen
Journal of Applied Polymer Science 2005 Volume 97(Issue 5) pp:1891-1898
Publication Date(Web):21 JUN 2005
DOI:10.1002/app.21923
The pervaporation performance of cellulose acetate (CA) membranes prepared from acetone (AC), acetone/tetrahydrofuran (AC/THF), acetone/chloroform (AC/CF), and acetone/cyclohexane (AC/CYH) was studied for separating MeOH/MTBE (methyl tert-butyl ether) mixture with 5 (wt) % MeOH. The dilute-solution properties and Huggins constant (KH) of CA dissolved in AC and AC/solvent mixtures with 15 vol % of the second solvent (tetrahydrofuran, chloroform, or cyclohexane) were examined. J and α of the CA membranes were affected by the types of solvent mixtures used to prepare the casting solutions. Under the same conditions, the membrane with AC/CYH had the highest J value and the lowest α value, and it was followed by the membranes with AC/CF, AC/THF, and AC. The increasing value of J and decreasing value of α for the CA membranes from different solvent mixtures were in good agreement with the increasing value of KH of CA in corresponding solvent mixtures. Furthermore, differences in the morphology from scanning electron microscopy images of the cross sections or from atomic force microscopy photographs of the surfaces of the membranes existed, and they provided proof of the different pervaporation performances of the CA membranes prepared from AC and AC/solvent mixtures. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97:1891–1898, 2005
Co-reporter:Quanfu An;Liyun Yu;Yingwu Luo;Xinzhi Liu
Journal of Polymer Science Part A: Polymer Chemistry 2005 Volume 43(Issue 9) pp:1973-1977
Publication Date(Web):23 MAR 2005
DOI:10.1002/pola.20622
Polyacrylonitrile (PAN) was synthesized in DMF by RAFT employing azobis(isobutyronitrile) (AIBN) as the initiator and 2-cyanoprop-2-yl dithiobenzoate (CPDB) as the chain transfer agent. The polymerization rate studied was directly proportional to [AIBN]0.94 and negative exponent to [CPDB], and a kinetic equation was obtained as Rp = k[AIBN]0.94[CPDB]−0.43[M] at 65 °C.
Co-reporter:Q.F An, J.W Qian, H.B Sun, L.N Wang, L Zhang, H.L Chen
Journal of Membrane Science 2003 Volume 222(1–2) pp:113-122
Publication Date(Web):1 September 2003
DOI:10.1016/S0376-7388(03)00260-6
Binary blends and their blend membranes of poly(vinyl chloride) and low molecular weight ethylene-co-vinyl acetate copolymer with 38 wt.% VA content (PVC/EVA) have been prepared by solution blending. The compatibility of the blends was investigated by viscometry and Fourier transform infrared (FTIR). It was found that the PVC is compatible with the EVA when EVA weight fraction (WEVA) is less than 0.25 or larger than 0.45. The blend membranes with WEVA≤0.15 have good resistance to benzene/cyclohexane mixtures with benzene content up to 50 wt.% at 30 °C. Both degree of swelling and the permeation flux of these blends membranes increase greatly with increasing WEVA from 0 to 0.2.
Co-reporter:Qiang Zhao, Jinwen Qian, Meihua Zhu and Quanfu An
Journal of Materials Chemistry A 2009 - vol. 19(Issue 46) pp:NaN8740-8740
Publication Date(Web):2009/10/14
DOI:10.1039/B912578G
Polyelectrolyte–polyelectrolyte complexes/multiwall carbon nanotubes (PECs/MWCNTs) nanocomposites have not been prepared until now because PECs are generally insoluble and infusible. In this work, solution-processable PEC/MWCNT nanocomposites and their membranes were prepared by in situ incorporation of MWCNTs into bulk PECs. The ionic complexation between poly(diallyldimethylammonium chloride) (PDDA) and sodium carboxymethyl cellulose (CMCNa) in the presence of MWCNTs was followed by ζ potential and optical transmittance measurements. Structures of PEC/MWCNT nanocomposites were characterized by FT-IR, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). It is found that MWCNTs are encapsulated by a layer of PEC and dispersed in a PEC matrix mainly on a single nanotube level. Mechanical properties of the nanocomposite membrane loaded with 7 wt% MWCNTs are greatly improved, showing 2.6 times higher tensile strength and 1.8 times higher modulus as compared with that of the pristine PEC. PEC/MWCNT nanocomposite membranes also display very high performance in pervaporation dehydration of isopropanol. This high pervaporation performance is reproducible with cycling feed temperatures and stable with increasing operation time up to 20 days.
Co-reporter:Qiang Zhao, Jinwen Qian, Quanfu An and Binyang Du
Journal of Materials Chemistry A 2009 - vol. 19(Issue 44) pp:NaN8455-8455
Publication Date(Web):2009/10/05
DOI:10.1039/B911386J
A novel method for speedy fabrication of free-standing layer-by-layer (LbL) multilayer films in salt free media, and without the need for a sacrificial sublayer is described by using two different polyelectrolyte complex (PEC) nanoparticles as LbL self-assembly building blocks. Negatively charged polyelectrolyte complex particles (PEC−) consisting of poly(diallyldimethylammonium chloride)/sodium carboxymethyl cellulose (PDDA/CMCNa), and positively charged polyelectrolyte complex particles (PEC+) consisting of PDDA/poly(sodium-p-styrenesulfonate) (PDDA/PSSNa) were prepared and characterized by FT-IR, zeta-potential (ζ potential) and transmission electron microscopy (TEM). The LbL self-assembly of PEC+/PEC− and PDDA/PEC− was followed by quartz crystal microbalance (QCM), optical transmittance, UV-vis absorption spectroscopy and atomic force microscopy (AFM). QCM results show that the thickness growth rate of the PEC+/PEC− pair is 9 times faster than that of the PDDA/PEC− pair and this result is also supported by optical transmittance and UV-vis absorption. A robust free-standing multilayer film of (PEC+/PEC−)25 can be easily peeled off from the substrate after being cross-linked in 3.5 wt% glutaraldehyde (GA) (80 °C, 50mins). Field emission electron scanning microscopy (FESEM) indicates that both the surface and cross-section of the multilayer film display layered structures. Furthermore, multiwall carbon nanotubes (MWCNTs) can also be uniformly incorporated into the free-standing LbL multilayer film by pre-incorporating MWCNTs into PEC− particles. The experimental results show that using oppositely charged PEC particles as LbL assembly components is a speedy and convenient method to fabricate free-standing LbL multilayer films either with or without nanofillers.
Co-reporter:Zhangliang Gui, Jinwen Qian, Mingjie Yin, Quanfu An, Bobo Gu and Aping Zhang
Journal of Materials Chemistry A 2010 - vol. 20(Issue 36) pp:NaN7760-7760
Publication Date(Web):2010/08/03
DOI:10.1039/C0JM01476A
Three-component multilayer films were prepared by consecutively depositing a polycation blend of poly(4-vinylpyridiniomethanecarboxylate) (PVPMC) and poly(diallyldimethylammonium) (PDDA) with poly(acrylic acid) (PAA). The self-assembly and disintegration behavior of the multilayer films were investigated in details by UV-vis absorption spectroscopy, quartz crystal microbalance (QCM) and atomic force microscopy (AFM). It was found that nanoporous PDDA/PAA multilayer films can be obtained conveniently by partly disintegrating (PVPMC + PDDA)/PAA multilayer films in a 0.15 M NaCl solution. A novel fast response fiber-optic pH sensor was successfully prepared by constructing nanoporous self-assembly multilayer films on the thin-core fiber interferometer (TCFMI) surface. The response time of a fiber-optic pH sensor deposited with nanoporous PDDA/PAA multilayer film (20 s rise time (tr) and 15 s fall time (tf)) was only one-tenth of that with the nonporous PDDA/PAA multilayer film (240 s and 160 s for tr and tf).
Co-reporter:Zhangliang Gui, Jinwen Qian, Quanfu An, Qiang Zhao, Huangtao Jin and Binyang Du
Journal of Materials Chemistry A 2010 - vol. 20(Issue 8) pp:NaN1474-1474
Publication Date(Web):2009/12/24
DOI:10.1039/B918170A
The self-assembly and disintegration behavior of polyzwitterion, poly(4-vinylpyridiniomethanecarboxylate) (PVPMC), and negatively charged polyelectrolyte, poly(acrylic acid) (PAA), layer-by-layer (LbL) multilayer films were investigated in detail by using UV-vis absorption spectroscopy, quartz crystal microbalance (QCM) and atomic force microscopy (AFM). The results indicated that the PVPMC/PAA multilayer films grew linearly with increasing bilayer number. The disintegration rate of PVPMC/PAA multilayers could be well controlled by varying the concentration of salt in aqueous solution. It was found that PVPMC/PAA multilayer films could be completely disintegrated in 0.9% normal saline solution within 15 min. Such controllable disintegration behavior rendered the PVPMC/PAA multilayer as an excellent sacrificial sublayer for fabricating free-standing LbL multilayer films. Free-standing multilayer films were then successfully fabricated by LbL self-assembly of positively charged polyelectrolyte complex (PEC), made from poly(diallyldimethylammonium) (PDDA) and poly(sodium 4-styrenesulfonate) (PSS), and negatively charged PSS with PVPMC/PAA as a sacrificial sublayer, which was disintegrated in 0.9% normal saline solution. The obtained free-standing films had good mechanical properties with 24.1 MPa tensile strength at break and 0.56 GPa Young's modulus.
Co-reporter:
Analytical Methods (2009-Present) 2012 - vol. 4(Issue 5) pp:
Publication Date(Web):
DOI:10.1039/C2AY05791C
A novel type of fiber-optic mercury ion (Hg2+) sensor was prepared by coating poly (N-ethyl-4-vinylpyridinium chloride) (P4VP·HCl) and poly (sodium-p-styrenesulfonate) (PSS) ultrathin film on the surface of a thin-core fiber modal interferometer (TCFMI) with layer-by-layer (LbL) electrostatic self-assembly method. The fabricated TCFMI Hg2+ sensor exhibits a high selectivity to Hg2+ and its detection limit and response time are 10−9 M and 30 s, respectively. The LbL electrostatic self-assembly process is monitored with a quartz crystal microbalance (QCM) and UV–vis spectroscopy for film growth. Atomic force microscopy (AFM) and field emission scanning electron microscopy (FESEM) were used to characterize the morphology of the ultrathin film. Both demonstrated nanoporous film, which is helpful in shortening the response time of the TCFMI Hg2+ sensor.
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![Poly[thio(2,2-dimethyl-1,3-propanediyl)]](http://img.cochemist.com/ccimg/28800/28758-47-6_b.png)
