最新刊期
卷 ， 期 8 ， 2006
- 摘要：Hydrophilic monomers polyethyleneglycol methacrylate(PEGMA)and hydroxyethyl methacrylate (HEMA)were selected to copolymerize with N—isopropylacrylamide(NIPAM)to prepare temperature—sensitive copolymer microgels containing functional —OH groups in the side chains of different lengths．Investigations on the microgels indicated that incorporation of PEGMA and HEMA have different influence on the deswelling behavior of the microgels．Incorporation of PEGMA nlakes the volume-phase transition temperature(VPTT)of the P(NIPAM—co—PEGMA)microgels to shift tO higher temperature and the deswelling ratio of the microgels to decrease with the increase of the feed ratio．While incorporation of HEMA causes the VPTT of the P(NIPAM—co—HEMA)microgels to shift to lower temperature and the deswelling ratio of the microgels to increase first and then decrease with the increase of the feed ratio．The micogels has the largest deswelling ratio when the feed ratio of HEMA is 8 mol％．
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发布时间：2021-03-19 - 摘要：The aqueous two—phase copolymerization(ATPC)of(2-methacryloyloxyethyl)trimethylammonium chloride(DMMC)and acrylamide(AM)in the aqueous sdution of poly(ethylene glycol)(PEG)is studied and compared with homogeneous aqueous solution copolymerization(HASC)．The reactivity ratios of DMMC／AM homogeneous aqueous solution copolymerization are rDMMC=1．77 and,rAM=0．32．The 95％ and 99％ joint confidence regions are also calculated．The conversion versus time curves and the composition of DMMC—AM copolymers are compared in two copolymerization systems,which shows that the reaction rate of ATPC is more quickly than that of HASC,but the final conversions are almost the same；the composition of DMMC—AM copalymers in ATPC is obviously different from that of in HASC．The partition coefficients of DMMC,AM and the copolymer of DMMC—AM at 65℃,under the reaction condition are determined,K1=0．035,K20．125 and Kp=0．011,respectively．Base on the polymerization mechanism of ATPC and the partition coefficients of monomers and copolymer,a new method of calculating the copolymer composition is presented for ATPC．The copolymer composition calculated by this method is in agreement with the experiment data．
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发布时间：2021-03-19 - 摘要：The degradation properties of polystyrene in supercritical benzene,toluene,ethylbenzene and p-xylene were studied between 340～370℃ using a quick process．Benzene hydrocarbons are the fine solvents of polystyrene．All the solvents have unique properties such as excellent heat transfer and mass transfer at supercritical conditions,and the degradation conversions of polystyrene were similar using different solvents．The conversion of polystyrene was close to thorough degradation when the temperature reached 370℃．Supercritical degradation of polystyrene in toluene improved the liquid product yield close to 97％ while reducing the gas and residue oil less than 1％ and 3％,respectively．The products are mainly composed of benzene,ethylbenzene,xylene,styrene,α-methylstyrene etc．But it is noted that the yield of styrene was quite different in different superedtical solvents．The experiments showed that the yield of styrene was much higher using supereritical toluene as solvent than that with other solvents．The yield of styrene obtained from polystyrene in superoritical toluene at 350℃ for 30 min reached a value of 75．5 wt％．The reaction mechanism consists of depolymerization of polystyrene and secondary reactions．The result showed that supercritical solvents affected the secondary reaction differently,because the styrene obtained from degradation could not separate out from the system quickly．Moreover,among the solvents employed in our work,toluene was founded to be the most effective supercritical solvent to recovery styrene from polystyrene．Based on the continuous distribution kinetics,the madel of polystyrene degradation was developed at the mechanistic level using popullation balance equations formulated via the method of moments．The activation energy of polystyrene degradation in supercritieal toluene obtained from Arrhenius equation is 138．4 kJ·mol-1．
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发布时间：2021-03-19 - 摘要：The nano-SiO2／acrylate resin composite latex was synthesized by in situ emulsion polymerization of methyl methacrylate(MMA)and butyl acrylate(BA)in the presence of nano—SiO2 particles,which were modified by silane coupling agent 3-(trimethoxysilyl)propyl methacrylate．The surface properties and dispersibility of nano-SiO2 after modification,chemical structure,Zeta potential and diameter distribution of the composite latex prepared and thermal stability of the hybrid film formed bY the composite latex were investigated by Fourier transform infrared spectrometer(FT-IR),transmission electron microscopy(TEM),Zeta meter,Zeta Plus apparatus(dynamic light scattering method)and thermogravimetric analysis(TGA),respectively．After modification with silane coupling agent,silane was grafted onto the surface of nano—SiO2 to form the organic layers,which were able to efficiently prevent the silica nanoparticles from aggregation in the in situ emulsion polymerization system and improve the compatibility of silica nanoparticles with the acrylate monomers．The nano—SiO2／acrylate resin composite latex prepared had the properties of silica nanoparticles and pure acrylate latex but was not simply a combination．Strong chemical bonding tethered the silica and acrvlate chains to form the core／shell structural composite latex．Consequently,the hybrid film formed by the composite latex exhibited a better thermal properties than the pure acrylate latex film．
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发布时间：2021-03-19 - 摘要：The assembly process of a particular collagen,the fibrous long spacing collagen formed by adding α1-acid glycoprotein,was studied in detail．The pH of the mixture collagen and α1-acid glycoprotein was changed by dialysis．In each pH stage,stable intermediate structures were resolved by atomic force microscopy(AFM)．The reliable and high-resolution images were obtained．The intermediate morphologies and diameters in every stage are observed by correlation the fibil diameters with length-wise growth in native type fibils and hy comparing the diameters and their morphologies of segmental long spacing collagen crystallites．These experimental studies demonstrated clearly the existence of intermediates in the formation process of fibrous long spacing collagens．
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发布时间：2021-03-19 - 摘要：The confined crystallization behavior of polycaprolactone(PCL)in thin and ultrathin films was studied by AFM(atomic force microscopy)．It was found that the crystalline morphology of PCL depended on the film thickness．When the thickness d>2Rg(radius of gyration),the polymer can crystallize into spherulites；when RgRg,the dense—branch morphology and dendrites could be found；when dRg,the“islands”structure could be obtained．Moreover．the effects of the crystallization temperature,substrate and the molecular weight on the cry-stalline morphology were discussed．It was shown that the crystallization of PCL in thin film is a diffusion-cuntrolled process,and it can be explained by diffusion—limited aggregation．
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发布时间：2021-03-19 - 摘要：A novel hyperbranched azo precursor polymer containing electron donor-acceptor type azohenzene chromophores was synthesized by step—growth polymerization of an AB2 monomer,di[2-(N-ethylanilino)ethyl]-5-aminoisophthalate,through azo coupling reaction．The hyperbranched precursor polymer was then reacted with the diazonium salts of 4-amino benzonitril to introduce another kind of donor-acceptor azo chromophores in the peripheral groups．The structure and properties of the azo polymers were characterized by the spectroscopic methods and thermal analysis．The photo-induced dichroism of the hyperbranched polymer was studied and the orientation order parameter of the polymer was estimated to be 0．063．Thin films of the hyperbranched azo polymers were used to fabricate surface-relief-gratings(SRGs)by exposing the thin films to an interference pattern of Ar+ laser beam at modest intensities(150 mW／cm2)．The azohenzene chromophore introduced by pest-azo-eoupling reaction in the para-positions of the terminal azobenzene units shows a significant effect on the SRG inscription rate．The hyperbranched azo polymers can potentially be used for applications such as reversible optical data storage,photoswitching,sensors,and other photo—driven devices．
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发布时间：2021-03-19 - 摘要：A novel polymer PAPE．containing electron donator-acceptor azobenzene chromophores in the main chain,has been synthesized by azo-coupling reaction．The azo polymer was characterized by1H-NMR,UV—Vis spectrometry and thermal analysis．The λmax of the polymer film and DMF solution determined to be 445 nm and 446 nm,respectively．The number average molecular weight determined by GPC was Mn=5600 with a polydispersion index 2．2．The glass transition temperature(Tg)of the polymer was 132℃ observed from DSC thermogram．The results showed the azo polymer can be successfully synthesized through ago—coupling reaction．The synthetic scheme demonstrated in this work is a feasible way to prepare main-chain azo polymers under an extremely mild condition．Dichroism was optically induced in the PAPE films under the irradiation of Ar+ laser beam at 488 nm．and the orientational order parameter obtained was 0．03．Surface—relief-gratings were observed on PAPE films after irradiated by an interference pattern of Ar+ laser beam for 1000s．The surface modulation depth and the grating spacing were measured by AMF to be 89 nm and 900 nm．
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发布时间：2021-03-19 - 摘要：In order to improve the redisperisibility of nanocrystalline cellulose(NCC)particles,three grafted reactions with acetylation,hydroxyethylation and hydroxypropylation,respectively were introduced to modify the NCC particle surface．The most advantages of these three methods were that the reaction condition was simple and was easily controlled,while the redispersibility of the resulting products was improved distinctly at the same time．The properties of the modified NCC were characterized by FT-IR,13C-NMR,TEM and TGA．The results showed that the products of the modified NCC,after desiccation,could be dispersed again in the proper solvents to form stable suspensions by ultrasonic treatments,and the diameter of the modified NCC particles did not increase clearly． However,their thermal behaviors were different．The beginning decomposition temperature of the products that NCC was surface modified via hydroxyethylation or hydroxypropylation,respectively,was distinctly lower than that of NCC via acetylation,due to their low degree of crystallinity．
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发布时间：2021-03-19 - 摘要：A novel inorganic compound poly(phosphazene trisulfide)was synthesized．The polymer’s molecular structure was determined by element content analysis and IR spectrum．It’S microscopic morphology was characterized by specific surface area,granularity analysis and scanning electron microscopy(SEM)．The effective working temperature is under 300℃．which is ascertained by thermogravimetric analysis．In cycle volt-ampere experiments．the reversible electrochemical redox reaction occurred at 2．25 V(versus Li／Li+for the reduction process)and 2．51 V(versus Li／Li+for the oxidation process)．The first discharge capacity of the polymer is 745．2 mAh·g-1,and the polymer can hold the discharge capacity at 708．8 mAh·g-1 after 60 repeated cycles．Taking into consideration the incombustibility,the conductivity,high capacity density and excellent cycle ability of this polymer,poly(phosphazene trisulfide)is a promising cathode material and has a huge application potential.
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发布时间：2021-03-19 - 摘要：Preparation of a biperous polymeric stationary phase for high-speed flowthrough chromatography was reported Using calcium carbonate suspension(200 g/L)and organic solvent(mixture of cyclohexanol and dodecanol)as the porogenic agents,a novel hiperous matrix has been prepared by ultraviolet photo-polymerizing monomers of glycidyl methacrylate and ethylene glycol dimethacrylate by(W／O)／W emulsification．The matrix was modified with diethylamine to create an anion exchanger(DEA—B)．It was found that there was two families of pores (micropores and superpores)in DEA-B,but there was only microperes in the microporous beads(DEA—M)prepared bv O／W emulsification．The two families of pores in DEA-B were in the range of 50—200 nm and 500—5000 nm,respectively,while the pores of DEA—M were mainly in the range of 50—200 nm．The hydrated density and particle size of DEA—B were 1．08 g／mL and 46．3 μm,respectively,similar to those of DEA-M(1．10 g／mL and 45．2 μm)．Operated at a mobile phase velocity of 150 cm／h,the DEA-B column could be used to purify a 5．4 kb plasmid DNA．but the DEA-M columu failed to do that at the same condition．Then,HPLC pure plasmid DNA was were obtained with the DEA-B column operated at 1500 cm／h．The results indicated that DEA-B colulmn was promising for high-speed chromatography purification of plasmid DNA．
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发布时间：2021-03-19 - 摘要：Bindegradable polyesters based on 1,4-succinlc acid and different ratios of 1,4-butanediol and 1,3-propanediol units were synthesized from polyeondensation of the appropriate mixture of the monomers．The crystal structure and melt crystallization kinetics of poly(butylene succinate-co-propylene succinate)(PBSPS)copolyesters have been investigated by means of 1H—NMR,WAXD,DSC and POM．The copolyester composed of BS and PS units has been identified to have the same crystal structure as that of paly(butylene succinate)(PBS)homopolymer,suggesting that only PBS sequences crystallize while the PS units are in an amoiphous form．Multiple melting peaks on the melting curves were observed during heating process,and DSC analysis has demonstrated that melt- recrystallization takes place during heating process．Isothermal crystallization kinetics of PBSPS has been analyzed by the well known Avrami equation．The 2．2—2．8 range of Avrami exponential values n of PBSPS in isothermal crystallization indicated that the mechanism of crystallization was a heterogeneous nucleation with spherical growth geometry．The banded spherulites were observed in PBSPS and the spherulitic morphology was affected by the crystallization temperature and the composition of copolyesters．
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发布时间：2021-03-19 - 摘要：Two optically active polybinaphthyls P-1 and P-2 were synthesized by(R)-3,3'-diiodo-2,2'-bisbutoxy-1,1’-binaphthyl((R)-M-1)and(R)-6,6'-dibromo-2,2'-bisbutoxy-1,1．-binaphthyl((R)-M-2)with 1,4-divinyl-2,3-bisbutoxy—naphthalene(M-3)via Heck coupling reaction catalyzed by PdAc2,respectively．Their structure and properties were characterized by NMR,GPC,FT-IR,UV,circulal dichrosim(CD),fluorescent spectroscopy and thermal analysis．The butoxy substitutents on naphthyl and binaphthyl rings as side chains of the polymers can improve their solubility in organic solvents and make them easy to be processed as electro—optical sensors．Both polymers show high thermal stability and have strong blue fluorescence due to the efficient energy migration from the extended π-electronic structure of the polymers to the chiral binaphthyl core．Photoluminesenee effcieneies(φPL)of P-1 and P-2 are 0．42 and 0．48,and they are expected to be used as blue—green emitting polymet matefials．
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发布时间：2021-03-19 - 摘要：The complex Sm(OPri)(TTA)2 was synthesized,and the Sm(OPri)(TTA)2／PMMA photoluminescent polymer was prepared by coordination bulk polymerization of rare earth complex and methyl methacrylate(MMA)．The complex and polymer have been characterized by FT-IR,1H-NMR,XRD,dynamical mechanical thermal analysis (DMTA),FS and ESEM etc．The results show that the Sm(OPri)(TTA)2／PMMA exhibits strong characteristic luminescence of samarium ion4G5/2→6H5/2,4G5/2→6H9/2 at 562,598,644 nm respectively under excitation with radiation of 396 nm and its luminescent strength is as high as that of Sm(TTA)3／PMMA．Moreover the storage modulus(E'),glass transition temperature(Tg)and viscous flow temperature(Tf)of the polymer are higher than those of PMMA．DMTA indicates that Sm(OPri)3／PMMA shows a crosslinking structure,whereas Sm (OPti)(TTA)2／PMMA shows a linear structure．
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发布时间：2021-03-19 - 摘要：3-Dimensional chitosan(CS)materials with high mechanical properties have been prepared via in-situ precipitated method．Owing to the existence of hydrophilie groups,the structure and properties of CS materials is easily affected hy the hydrated water．Water sorption in the CS material is Fickian in nature.Thermal analyses revealed the existence of up to three energetically distinct states of water：bound water,intermediate water and free water in the water saturated CS rod,each type of water have different effects on the mechanical properties of the material．Initially,there exists thermal stable bound water that can not be easily removed.Interaction between water and CS results in a strengthening of the hydrogen bond network．Subsequent absorbed intermediate water of CS material in the water environment acts as a plasticizer,forming water-water bridges that loosen the hydrogen bonding network．Modeling of the modulus and strength of CS rods with the Fermi’s equation for the fall in the modulus and strength as a function of warer content under isothermal condition was fitted．Differ to other CS blends,this intermediate water is non-freezing．In the later stage of water sorptiou,water enters the CS and loosely adhered as free water which is freezing,undergoes no thermal phase transition over the range of temperatures normally associated with bulk water,having few effects on the mechanical properties of the CS rod.
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发布时间：2021-03-19
Research Article
- 摘要：A new monomer,vinyltriallylsilane(CB3),having functionnal groups with different hydrosilylation reactivity was designed and synthesized by allylation reaction from vinyltrichlorosilane．Then,photocrosslinkable hyperbranched poly(siloxysilane)with terminal allyl groups was prepared via hydrosilylation reaction of vinyltriallylsilane(CB3)and dimetbylbis(dimethylsiloxy)silane(A2)monomers at the presence of Karstedt catalyst, and characterized by means of FTIR,1H—NMR,29Si—NMR,and SEC／RI／MALLS technology．The polymerization process of A2 and CB3monomers Was studied in situ by using FTIR．It was found that silicon hydride would preferentially react with vinyl groups during the reaction．This can cause to the generation of an intermediate with one Si—H and three allyl groups．By using it to conduct fuaher self-polymerization,hyperbranehed polymer can be obtained．The degree of branching of the resuhing hyperbranched poly(siloxysilane)was calculated to be 0．44 by quantitative29 Si—NMR spectroscopy．and the weight average molecular weisht was l2．1 kg／mol with its polydispersity of 2．52．Finally．the UV curing behavior of the resulting polymer initiated with different photoinitors was also investigated．
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发布时间：2021-03-19 - 摘要：A photo-crosslinkable ployfluorene with oxetane group was synthesized and characterized by NMR, elemental analysis,etc．It was evidenced that the introduction of photocrosslinkable oxetane group has very little effect on the blue-light-emission of polyfluorene．Insoluble polyfluorene films were obtained by crosslinking with the addition of the triarylsulfonium salt photoinitiator under UV irriation．It was revealed that the optoelectronic properties of crosslingked polyfluorene displayed little change compared with uncrosslinked polyfluorenes．
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发布时间：2021-03-19
Research Bulletin
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