最新刊期
卷 ， 期 7 ， 2011
- 摘要：The solid alkaline electrolyte membranes have been succesfully prepared from poly(vinylalcohol) (PVA),poly(vinyl alcohol)/poly(vinyl pyrrolidone) (PVA/PVP) and poly(vinyl alcohol)/poly(ethylene glycol) dimethyl ether (PVA/PEGDE) by doping different concentrations of KOH aquaous solutions.The morphology,microstructure,thermal stability,ionic conductivity and chemical stability of the membranes were investigated in detail.The wholly compact and homogeneous composite membranes were obtained due to the good compatibility between PVA and PVP and/or PEGDE,and no obvious phase seperation was observed.The ionic conductivity of the composite membranes was enhanced greatly with increasing the content of PVP and/or PEGDE in polymer.The measured conductivity of the membranes reached as high as up to 210-3 Scm-1 by addition 100% content of PVP and 1.4310-3 Scm-1by addition 25% content of PEGDE.The obtained PVA/PVP and PVA/PEGDE membranes exhibited excellent thermal stability and alkaline tolerance where no obvious decrease in ionic conductivty was observed even after the membrane being treated in 10 molL-1 KOH at an elevated temperature of 80℃.FTIR spectra results suggested that the KOH absorption of the membranes increased at elevated treatment temperatures,which gave rise to an increase in the OH- charge carriers density.In addition,the methanol uptake of PVA/PVP/KOH and PVA/PEGDE/KOH membranes showed almost no changes after conditioned at elevated temperatures and,were 4 times lower than that of Nafion115 membrane after conditioned at 100℃.It could indicate a potential feasibility as a promising PVA based solid alkaline electrolyte membrane for alkaline fuel cells.关键词：Solid alkaline electrolyte membranes;Poly(vinyl alcohol);Poly(vinyl pyrrolidone);Poly(ethylene glycol) dimethyl ether;Chemcial stability
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发布时间：2021-03-19 - 摘要：A new rubber functional agent with dithiocarbamate group,carboxyl groups and lanthanum ion,called lanthanum glutamic dithiocarbamate (La-GDTC),was synthesized and its chemical structure was characterized by FTIR and element analysis.The interfacial interactions of SBR/La-GDTC/SiO2composites were measured by toluene swelling-equilibrium test under room temperature.The crosslinking density data of SBR/La-GDTC/SiO2 composites turned out,with the increasing loading of silica content,that the crosslinking density evolved to a high extent considerably,without respect to the obstructed effect of the silica particles on sulfur crosslink reaction.The swollen Gibbs free energy parameters of the composites G decreased dramatically and S increased obviously,both of which interpreted that the chemistry environment of the silica particles in the rubber hybrid composites changed to some extent,leading to a more heterogeneous network existed in the composites and a different chemical bonding structure between the rubber matrix and inorganic particles.Also,the interphase interaction parameter C,obtained from Kraus equations,was the value of 2.02 and verified the reinforcement between SBR and silica particles via the hydrogen bonds and chemical bonds between the La-GDTC and silica particles.The tensile strength,elongation at break and tear strength all pointed out that the mechanical properties of the La-GDTC system were much higher than those of the ZDC system.Also,in the SEM photographs,well-dispersed silica fine particles and more fluctuated surface of the La-GDTC-4 were attained,however,the silica clusters aggregation and smooth surface of the fracture were observed in the ZDC-4,implying that the interface interaction between the SBR/silica particles of the La-GDTC system was much stronger than that of the ZDC system.Based on the fore-mentioned experimental observation,an interphase structure between the rubber matrix and the inorganic particles was discussed.关键词：Styrene-butadiene rubber (SBR);Silica;Rare earth acceleratorm;Interfacial;Swelling-equilibrium
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发布时间：2021-03-19 - 摘要：Syndiotactic polystyrene was synthesized by emulsion polymerization using Ni(COD)2 and ligands containing P and O as catalyst.The reaction kinetics of the above process was studied.The product was characterized with 13C-NMR,1H-NMR,GPC,TEM,DSC and TG etc.The best polymerization condition for this reaction system was found to be:emulsifier 1.50 g, [St]0=1.79 molL-1,T=60℃,t=2 h, [Ni(COD)2] =1.10 mmolL-1,the conversion was 78%.The activity of the catalyst was 662.14 gPS(gNih)-1.The emulsion particle size was 100~120 nm from the results of particle size analysis and TEM techniques.Very good thermal stabilities of latex are observed in the temperature range of ambient temperature up to ca. 376℃.The GPC analysis results show that:the weight average molecular weight Mw is 1.64106,while the number-average molecular weight Mn is 9.79105 and the width of molecular weight distribution is 1.6. The 13C-NMR,1H-NMR and TG analysis results proved the syndiotactic structure.The polymers exhibit glass transition temperature of Tg=114.95℃.The rate of polymerization (Rp) was found to be dependent on the monomer,catalysts concentrations.Preliminary study on the kinetics of the polymerization indicates that:the apparent activation energy Ea is 20.76 kJ/mol,the rate equations are:Rp=1.687[St]0.241[Ni(COD)2]0.542(when [St]1.79 molL-1),Rp=0.03683[St]-0.187[Ni(COD)2]0.542 (when [St]1.79 molL-1).关键词：Syndiotactic polystyrene;Catalysts;Kinetics
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发布时间：2021-03-19 - 摘要：An anionic water-soluble polymer was synthesized by Suzuki-coupling between 2,7-［bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-9,9-bis(3-(tert-butyl propanoate))］fluorene,2,7-dibromo-9,9-bis(3'-(tert-butylpropanoate))fluorene,and 2,5-dibromothiophene,which was followed by treatment in trifluoroacetic acid and aqueous Na2CO3 to afford the functional carboxylic acid groups,with number-averaged molecular weight about 9000 and polydispersity of 1.37.The polymer emits green fluorescence with a main peak at around 446 nm and a shoulder at about 464 nm.The absorption and fluorescence spectra of the polymer are strongly dependent on pH value owing to the partial protonation of carboxylate groups and the aggregation of the polymer chains.The change in polymer fluorescence upon interaction with different proteins in phosphate buffer solution (PBS) was also studied.The difference between the proteins is that bovine serum albumin (BSA) is negatively charged,histone is positively charged and hemoglobin is neutral.Strong fluorescence quenching of the polymer was observed in the presence of histone,the lowest quenching concentration was observed to be 510-8 mol/L.Under similar experimental conditions,whereas weak quenching was observed in the other proteins hemoglobin and BSA.The variation in the fluorescence of the polymer in the presence of different proteins is due to the different electrostatic interactions between the polymer and the proteins.关键词：Water-soluble conjugated polymer;Fluorescence quenching;Protein
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发布时间：2021-03-19 - 摘要：Barrier properties of light-induced ordered phase and thermo-induced ordered phase of azobenzene containing side-chain liquid crystalline polymers were investigated by a ferrous matrix surface oxidation method.Different mesogen distributions were obtained by linear polarized light irradiation and by annealing the as-cast film,and were characterized by polarized light microscopy (POM) under conoscopic observation.Upon a 473 nm linear polarized light irradiation,an interference figure was observed suggesting the formation of an in-plane arranged single-domain ordered phase.In contrast,the thermo-induced polydomain liquid crystalline(LC) phase showed a bright field vision when the sample was annealled at a temperature below its clear transition point,suggesting the formation of a randomly orientated multi-domain LC phase.Their permeation rates were obtained by measuring the surface oxidation rate of the ferrous matrix covered with differently arranged liquid crystalline polymer films.It was found that the barrier value of the orientated film was 2.5 times higher than those of the amorphous film,and about 1.25 times higher than that of the thermotropic liquid crystalline phase.Combining the conoscopic observation results,the gas permeation behavior in the liquid crystalline polymer films was proposed.Linear polarized light induced mesogens orientation and assembled a single-domain order phase,which eliminated the permeable boundary existed in the thermotropic polydomain liquid crystalline phase.Thus,the low value of permeability was attributed to a low diffusion coefficient in the ordered phase.关键词：Azobenzene;Liquid crystalline;Photoinduced orientation;Conoscopic observation;Barrier properties
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发布时间：2021-03-19 -
SYNTHESIS AND PROPERTIES OF POLY(PHTHALAZINONE ETHER SULFONE KETONE)S FROM 4,4'-DICHLOROBENZOPHENONE
摘要：As distinguished from the conventional preparation of poly(aryl ether ketone)s by utilizing 4,4'-difluorobenzophenone,a series of poly(4-phthalazinone ether sulfone ketone)s (PPESKs) were prepared from 4-(4-hydroxylphenyl)-2,3-phthalazin-1-one (DHPZ) with 4,4'-dichlorodiphenyl sulfone (DCS) and a less reactive but cheaper monomer,4,4'-dichlorobenzophenone (DCK) by solution polycondensation.The polymerization was conducted at 210℃ in sulfolane by two steps,which successfully resolved the problems resulted from the low reactivity of DCK in the nucleophilic substituent reaction.The inherent viscosities of the obtained polymers were in the range of 0.40~0.61 dL/g.The structures of the resultant polymers were characterized by FTIR and 1H-NMR.The properties of the polymers were also investigated.The polymers exhibited outstanding thermal properties.Their glass transition temperatures were in the range of 264℃ to 299℃,which is consisted with Fox Equation well.And their temperatures for 5% weight loss in nitrogen were above 500℃.The PPESKs can form transparent,strong and flexible films from their N-methyl-2-pyrrolidone NMP solution,and these films showed excellent mechanical properties with tensile strength above 68 MPa,Youngs moduli above 0.80 GPa and elongation at break above 19%.Thus this kind of polymers with low cost exhibits a promising wide market and applications in composites,high temperature adhesives and insulating coatings.关键词：Phthalazinone;Dichloroaryketone;Poly(aryl ether sulfone ketone)s- 14
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发布时间：2021-03-19 - 摘要：Phosphaphenanthrene-containing 4-ethynylbenzonate (MAT4) was grafted to glycidyl azide polymer (GAP) by click chemistry in the presence of CuI as catalyst.FT-IR analytical results confirmed the structure of the grafting polymer (G-M4) and revealed the click reaction between GAP and MAT4 in equal molar ratio.Compared with MAT4,the UV-Vis absorbance and the photoluminescence strength of G-M4 in dichloromethylene solution are obviously increased because the formation of triazole induces the increasing of total conjugated degree.When G-M4 molecules aggregate to a certain degree in a mixture of dichloromethylene and n-hexane,the photoluminescence strength of G-M4 proportionally increases,which shows obvious aggregation-induced emission enhancement (AIEE) property because the aggregation state of G-M4 restricts the intramlecular rotation of phosphaphenanthrene groups based on the - stacking and polarity interaction between the molecules.Due to J-aggregation,supramolecular structure between triazole rings in G-M4 and phosphaphenanthrene groups in adjacent G-M4 based on donor-accept interaction is formed.When the content of n-hexane is over 70%,the photoluminescence spectra of G-M4 obviously show two peaks,which are attributed to photoluminescence emission of intra- and extra-chains of G-M4,respectively.This novel phenomenon may enable the polymer to find applications in chemosensor,optical display and rewritable optical media.关键词：Phosphaphenanthrene;4-Ethynylbenzonate;Glycidyl azide polymer;Click chemistry;Aggregation-induced emission enhancement
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发布时间：2021-03-19 - 摘要：Nanosilica particles well dispersed in ethanol were modified by 3-(trimethoxysilyl)propyl methacrylate (MPS) and then re-dispersed into methyl methacrylate (MMA) and poly(methyl methacrylate) matrix via a media replacement process and an in situ bulk polymerization process, respectively.The MPS modified status of silica particles and its effects on the dispersion of silica particles in different media and polymer matrix were systematically investigated by FTIR,TG,DLS and TEM.It was found MPS oligomer was the main form for MPS coupling on silica particles surface.Excessive MPS dosage not only resulted in the formation of MPS homo-polymeric particles in media phase,but also the MPS oligomer thick layer on silica surface,which would inevitably induce the small-scale aggregation of silica particles.There existed an appropriate MPS coupling amount for excellent silica dispersity,which is mainly related with the apparent coupling density of MPS molecules on silica particles surface.When the apparent coupling density is 1.3~5.6 mol(m2SiO2)-1,the MPS coupling efficiency is acceptable and the modification of silica particles is sufficient.Only on this state,silica particles can be dispersed in the monomer and polymer matrix at the primary particles size level,even in the case of 20% silica content.The silica/monomer dispersion prepared via the above processes exhibited high silica dispersity,high silica content,high storage stability and high grafting controllability on silica surface.All of them imply that this kind of dispersion is avail to prepare silica/PMMA composite microspheres via in situ heterogeneous polymerization,and these microspheres would possess controllable morphology and controllable graft interface.关键词：Nanosilica particle;Silane coupling agent;Dispersity;Methyl methacrylate
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发布时间：2021-03-19 - 摘要：Polyaniline (PANI) microspheres containing Fe3O4 nanoparticles are prepared by means of electrospinning technology using a blending chloroform solution of dodecylbenzene sulfonic acid (DBSA) doped polyaniline (PANI) with polyethylene glycol (PEG) and Fe3O4 nanoparticles. SEM images indicate that composite microspheres of PANI/PEG/Fe3O4 are prepared by means of electrospinning technology, and the diameters are in the range of 2~5 m, which are significantly influenced by the concentration of PEG polymer, the applied voltage and the mass ratio of Fe3O4 in the polymers. With increasing the concentration of PEG, cohesive microspheres turn into regular ones, meanwhile the diameters increase. In comparison, the increasing applied voltage results in gradually reduced diameters of the microspheres. In addition, the microspheres are hardly affected by the addition of various amounts of Fe3O4nanoparticles. It is found that the addition of Fe3O4nanoparticles does not affect the polymeric chain structure of PANI. However, the added Fe3O4nanoparticles contribute superparamagnetic properties to the composite microspheres, especially the saturated magnetization (Ms) increases with the increase of the adding content of Fe3O4 nanoparticles. Furthermore, the conductive ratio of the electrospinning conduct is about 110-6 S/cm.关键词：Electrospinning technology;Conducting polyaniline;Microsphere structures;Sizes controlled;Supper-magnetic properties
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发布时间：2021-03-19 - 摘要：Transmission halographic polymer dispersed liquid crsytal grating with high spatial frequencies (3000 lp/mm), abbrivrated as HF-THPDLC, was fabricated, and the material system was investigated. In order to get the HF-THPDLC grating with high diffraction efficiency and perfect surface morphology, the average functionality of the reaction system was determined first. Therefore, the diffusion time of the pre-polymer monomer and the liquid crystal, the nucleation time of the liquid crystal and the gelation time of the polymer are on the same order. Consequently, the perfect surface morphology was obtained and the scattering loss of the grating was reduced. Secondly, small monomer NVP was added into the reaction system of fabricating grating, and the optimum concentration was found. The addition of NVP enhanced the degree of phase separation and got perfect surface morphology as well as higher refractive index modulation. And accordingly the diffraction efficiency of HF-THPDLC grating was remarkably improved. Experimental results indicated that when the average functionality was 3.2 and NVP concentration was 10%, the optical properties of the HF-THPDLC grating were the best and the diffraction efficiency reached 78.3%.关键词：Transmission HPDLC grating;Spatial frequency;Surface morphology;Diffraction efficiency
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发布时间：2021-03-19 - 摘要：Poly ( N-isopropylacrylamide-co-N-vinylpyrrolidone) [P(NIPAM-co-NVP)] copolymers were synthesized,and their reversible aggregation in aqueous solutions were investigated in the whole heating and cooling process with elastic light scattering (ELS) spectroscopy,fluorescence and dynamic light scattering (DLS).The ELS results indicated that IELS gradually increases in the heating process while decreases in the cooling process.Fluorescence spectra also suggested that the hydrophobic interaction occurred during heating and caused the aggregation of copolymer molecular chains and the increasing of fluorescence intensity,while the intensity was opposite during cooling owning to the dissociation of molecular chains.When the temperature increased,the hydrodynamic radius of this copolymer molecules measured by DLS increased rapidly at the LCST value and then decreased,and the cooling process was also contrary to the heating.Thus,fluorescence spectra and light scattering confirmed with the elastic light scattering in measuring the aggregation behavior of copolymer chains.Besides,ELS can get the conclusion easily that the copolymer with hydrophilic comonomer NVP has a higher transition temperature than the PNIPAM homopolymer has.It was concluded that reversible aggregation of P(NIPAM-co-NVP) copolymers in aqueous solutions could be described by ELS as well as by Fluorescence and DLS.关键词：Poly(N-isopropylacrylamide-co-N-vinylpyrrolidone);Reversible aggregation;Elastic light scattering;Fluorescence
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发布时间：2021-03-19 - 摘要：Poly(1,2-cyclohexylene carbonate) (PCHC) was prepared by copolymerization of carbon dioxide and cyclohexene oxide with Y(CCl3COO)3-ZnEt2-glycerin rare earth metal coordination ternary catalyst.The result polymer showed number average molecular weight (Mn) of 56.3103 with polydispersity index of 4.9. Though PCHC showed high glass transition temperature (Tg),PCHC was easy to degrade during melt processing,accompanied by severe deterioration of its mechanical performance,which constituted one of the main obstacles for commercialization of PCHC.In order to impove the thermal stability and mechanical properties of PCHC,the thermal decomposition reaction was compensated by the chemical chain extension reaction.At first,maleic anhydride was used as end-capper of PCHC to prevent its chain unzipping reaction,the MA and PCHC in weight ratio of 1 ∶100 were added into dichloromethane to make a 20 wt% solution,and refluxed at 41~43℃ for 48 h,then the polymer was precipitated by ethanol to obtain maleic anhydride end-capped PCHC (MA-PCHC).MA-PCHC was then subjected to chain extension reaction at 180℃ and 60 r/min in the a Haake mixer for 5 min using 2,2'-bis(2-oxazoline)(BOZ) as chain extender.The optimal chain extension condition was found when equimolar BOZ and carboxyl group in MA-PCHC were used,the Mn of MA-PCHC increased from 5.6104 to 12.4104.The thermal stability of PCHC after chain extension was greatly improved,compared with the as-polymerized PCHC,the thermal decomposition temperature at 5 wt% loss (Td-5%) for chain extended PCHC increased from 260℃ to 317℃, the Tg increased from 114℃ to 133℃,and most importantly,the melt viscosity increased by 30 times.It should be noted that no significant change in gelatin content was observed during chain extension reaction.Moreover,the chain extended PCHC showed tensile strength increase from 35.8 MPa (as polymerized PCHC) to 40.2 MPa,and the elongation at break increased from 4.59% to 6.22%,yielding phenomenon was observed in the stress-strain curve.Therefore,the chain extension strategy was effective to improve the mechanical performance of PCHC.关键词：Poly(1,2-cyclohexylene carbonate);2,2'-Bis(2-oxazoline);Maleic anhydride;End-capping;Chain extension
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发布时间：2021-03-19 - 摘要：Cationic and anionic PSt (polystyrene) latexes were synthesized using emulsion polymerization.The anionic PSt particles were treated using -aminopropyl triethoxysilane (KH550) and the surface of the particles in this anionic latex was thus changed from negatively to positively charged.PSt/TiO2 composite particles were then prepared through hydrolysis of TBT (tetrabutyl titanate) in a mixture of ethanol and water,in the presence of the above 3 types of PSt latex particles,respectively, i.e.anionic PSt,cationic PSt and the anionic PSt particles treated using KH550. Results showed that a clear PSt/TiO2 core-shell structure was obtained only by using the KH550 treated anionic PSt particles.When these core-shell composite particles were dispersed into tetrahydrofuran to dissolve PSt core,TiO2 hollow particles were clearly observed under TEM.The study on the influence of KH550 amount on PSt/TiO2 core-shell formation revealed that 0.1 g of KH550 was enough to change the anionic PSt particles from negatively to positively charged,more KH550 did not contribute to the formation of PSt/TiO2 core-shell particles.Using 5 mL of the KH550 treated PSt latex of 9.4% solids,appropriate amount of TBT should be controlled between 1 g to 2 g in order to get well formed TiO2 hollow particles.The mechanisms of the PSt/TiO2 core-shell formation and of TiO2 hollow particles were discussed.关键词：Polystyrene latex particles;KH550 modification;Core-shell composite particles;TiO2hollow particles
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发布时间：2021-03-19 - 摘要：Chloro(5,10,15,20-tetraphenyl-porphyrinato)-aluminum (TPPAlCl) in combination with bis(triphenylphosphine) iminium chloride (PPNCl) was used as binary catalyst for the copolymerization of cyclohexene oxide and CO2. After 9 h reaction at 80℃,poly(1,2-cyclohexylene carbonate) (PCHC) with narrow molecular weight distribution ( Mw / Mn =1.12)was obtained and the yield was as high as 97.2%.However,the number average molecular weight was only 6.8 103. Its found that the concentration and polarity of solvents have little effect on the chain transfer reaction,whereas a decrease in monomer concentration leads to a remarkable reduction in the chain transfer reactions,indicating that there exists obvious chain transfer to monomers.Furthermore,the structure of PCHC was analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF/MS) technique,upon which the mechanism of chain growth and chain transfer reaction in the polymerization process was proposed:during the copolymerization of cyclohexene oxide and CO2 catalyzed by TPPAlCl/PPNCl system,besides the added initiator,newly active centers were generated by chain transfer,thereby the number of the polymer molecules exceeded the number of the added aluminium porphyrin molecules.Furthermore,the narrow molecular weight distribution of the obtained polymer indicates that the rate of chain exchange is much faster than that of chain propagation.The reversibility of the rapid exchange reaction is the key of alternation of chain termination and chain propagation.关键词：Carbon dioxide;Poly(1,2-cyclohexylene carbonate);Aluminum porphyrin catalyst;Chain transfer reaction
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发布时间：2021-03-19 - 摘要：To endow polypropylene microporous membrane (PPMM) with adsorption selectivity to low-density lipoprotein (LDL),a versatile method was developed to covalently immobilize heparin on the PPMM surface.This was achieved by grafting acrylic acid (AA) on the PPMM surface by UV irradiation,and subsequent chemical binding of heparin with ethylenediamine as a spacer.The membrane surfaces were characterized by attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy.The hydrophilicity and blood compatibility of the PPMM surface were improved obviously by the surface heparinization.Water contact angle of the membrane surface was decreased from (1387.2) for the nascent PPMM to (35.12.7) for the heparinized PPMM with 7.39 g/cm2 heparin.An enzyme-linked immunosorbent assay (ELISA) was employed to analyze the adsorption of the LDL on the nascent and heparinized PPMMs.It was found that the surface heparinization greatly enhanced the adsorption of LDL both from single protein solution and binary protein solution containing human serum albumin (HSA),and the heparinized PPMM could selectively adsorb LDL from binary protein solution.In addition,the adsorbed LDL could be desorbed from the heparinized PPMM with sodium chloride solution,which indicated the adsorption was of reversibility.关键词：Polypropylene microporous membrane;Surface modification;Heparinization;LDL adsorption
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发布时间：2021-03-19
Research Article
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