最新刊期
卷 ， 期 6 ， 1999
- 摘要：According to the data obtained from Differential Scanning Calorimetry (DSC),the method of Jeziorny, Вороховский and a new approach proposed by our laboratry are applied to study the nonisothermal crystallization behavior of poly(3-dodecylthiophene) (P3DDT) and poly(3-octadecylthiophene) (P3ODT),and Kissinger method is used to get the value of the crystallization activation energy. The effect of the different alkyl substitution on crystallization is also investigated. In comparison to the methods of Jeziorny and Вороховский in which it can be found that the deviation from the line occurs in the later stage of crystallization,the new approach appears applicable due to the better linear relation. The values of the crystallization activation energy of P3DDT and P3ODT are estimated as 184.78kJ/mol and 246.93kJ/mol,respecivley, which implies that it is easiser to crystallize P3DDT than P3ODT.
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发布时间：2021-03-19 - 摘要：The synthetic thermo-responsive polymer azidoaniline-coupled poly( N-isopropylacrylamide/acrylic acid)(AzPhPIA) was photo-immobilized on Polystyrene Culture Plates. On the plates, STO cells were cultured for two hours. Under the low critical solution temperature (LCST 21.5℃), detachment experiment showed the cells which were cultured on the thermo-responsive polymer could not be detached completely as the serum-free cell culture. For investigating the effects of serum, we chose two serum protein (albumin and fibronectin) for cell attachment and detachment. The results showed that fibronectin was coated all the surface of plate, but albumin was pattern-coated on the plate and liked to coated on the surface of polystyrene. It was fibronectin which increased cell attachment so that cells soulld not be detached, and was due to hydrophilic of thermo-responsive polymer AzPhPIA not the attachment influence of albumin that cells were detached under the LCST.Surface analysis demonstrated that coated protein would not affect the wettability of AzPhPIA.
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发布时间：2021-03-19 - 摘要：A novel adsorbent for the adsorption of Low-density Lipoprotein(LDL) was prepared by immobilizing taurine onto the cross-linked polyvinyl alcohol bead.The adsorption results indicated that this type of adsorbent could cut down in vitro the concentration of LDL and VLDL selectively.It's adsorption efficiency and selectivity depended not only on the amount of taurine immobilized and the degree of cross-linking of the polyvinyl alcohol,but also on the beads size and serum taken from different patients.The total protein was slightly effected by this novel adsorbent.
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发布时间：2021-03-19 - 摘要：Methanesulfonic acid method was used to synthesize five acylated chitosans,i.e.acetyl chitosan,propionyl chitosan,butyryl chitosan,hexanoyl chitosan and heptanoyl chitosan.All derivatives demonstrated lyotropic liquid crystalline behavior.Cholesteric phase was shown by the presence of fingerprint textures.Substitution degree of propionyl chitosan in the range from 0.21 to 0.94 had no obvious effect on the critical concentration,because a small substitution degree such as 0.21 is large enough to destroy most of the hydrogen band of inter-and-intra-molecules.But the critical concentration(W/W)increased form 0.15 to 0.22,as the side chain length increased. This phenomenon can be explained by the drop of the rigidity of the chain. Typical droplet texture appeared in the biphase coexistence concentration region of all five acylated chitosans.The transition concentration from biphase coexistence to mesophase was also affected by the side chain length.Acylated chitosans were all water soluble and exhibited lyotropic liquid crystalline behavior in water.
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发布时间：2021-03-19 - 摘要：Thermosensitive magnetic microspheres were characterized by infrared absorption spectrum (IR),scanning electron microscope,atomic absorption sepectrometry,differential scanning calorimetry (DSC),laser diffraction particle analyzer etc.The results indicate the size of microspheres was Gaussian distribution, N-isopropylacrylamide(NIPAM) could copolymerized with styrene (St),and the glass transition temperature (Tg) of copolymers increased with increasing amout of NIPAM.The content of Fe3O4 was about20～100mg/g in the microspheres,which showed strongly magnetic response.The hydrodynamic size of thermosensitive magnetic microspheres was dependent on temperature and shrank about 10～20% above the lower criticle solution temperature(LCST) in water.
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发布时间：2021-03-19 - 摘要：Chemical by crosslinked PVC was synthesized by vinyl chloride/diallyl phthalate (VC/DAP) suspension copolymerization and processed to prepare plasticized sample. PVC prepared by VC/DAP copolymerization was composed of gel and sol fraction and the crosslinking density of gle was lower. It confirmed that chain entanglements existed in both gel phase and sol phase. PVC still exhibited the recrystallization ability as it was lightly chemical by crosslinked. The structure model of plasticized and lightly chemical crosslink network and physical crosslink network formed by chain entanglements and micro-crystallites were cooperated each other. The rheological, temperature-deformation behavior and permanent compression set of plasticized and lightly chemical by crosslinked PVC were influenced by chemical and physical crosslinking.
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发布时间：2021-03-19 - 摘要：Seed latex particles of polyvinyl acetate(PVAc) with narrow diameter distribution were first prepared by using ammonium persulfate as initiator, then unswelling and swelling seeded emulsion polymerization of methyl acrylate(MA) onto PVAc initiated by 2,2′-azobisisobutyronitrile(AIBN) were carried out at 60℃ in the absence of emulsifier. In order to investigate particle morphologies of various seeded latexes, a selective staining technique using phosphotungstic acid (PTA) was used under transmission electron microscopy(TEM) observation. Results showed that experimental particle size agree roughly with calculated particle size for all of seeded emulsion polymerizations, but particle mophologies are different. Under unswelling condition, taking into account the high water solublity of MA, its homonucleation in water was significant, and PMA secondary particles were formed and coagulated onto the PVAc particles, so initiation and polymerization loci of MA were both in PVAc seed particle and in water phase,and PMA domains were observed at the surface and inside of seeded latex particles when PVAc/MA weight ratios are 2 and 1. When PVAc/MA weight ratio decrease to 0.5,PMA-PVAc core-shell particle was observed. While under swelling condition, the inner of PVAc domains or core-shell structure were observed,and interpenetrating network structures were formed for different PVAc/MA ratios.
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发布时间：2021-03-19 - 摘要：The synthesis of poly(styrene-b-alkyl acrylate) and poly(styrene-b-methyl methacrylate) block copolymers by atom transfer radical ppolymerization (ATRP) with CuX(X=Cl,or Br)/2,2′-bipyridine (bipy) complex as the catalyst was studied in this work. When chlorine capped polystyrene (PSt-Cl) synthesized by ATRP was used to initiate the polymeriztion of methyl acrylate, ethyl acrylate or n-butyl acrylate in the presence of CuCl/bipy, well-defined poly(styrene-b-alkyl acrylate) block copolymers were obtained. However, when PSt-Cl or PSt-Br was used as macroinitiator to initiate the polymerization of the macroinitiator PSt-X(X=Cl.or Br),showing the blocking efficiency was low. While the ATRP of styrene with PMMA-Cl as the macroinitiator gave well-defined poly(methylmethacrylate-b-styrene) block copolymer. These results wereexplained according to the aifference of C-X bond dissociation energy between PSt-X and PMMA-X(X=Cl,or Br).
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发布时间：2021-03-19 - 摘要：Supernucleophilic polyamides as polymeric catalysts were prepared by means of syntheses and polymerization of several reactive monomers,such as dihydric acylchlorides and diols containing alkylaminopyridine groups,using 4-aminopyridine.Acetylation of tert-butanol was carried out in the presence of the polyamides.Results revealed that catalytic activity of the linear polyamides is higher than that of 4-(N,N-dimethylamino)pyridine (DMAP).However,the crosslinked resins are somewhat less effective than the linear analogues.
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发布时间：2021-03-19 - 摘要：Although the catalytic activity of hexaphenylcyclo-trisilazane trilithium salt is much lower than that of hexamethylcylotrisilazane trilithium salt due to the inductive and steric effect of phenyl group, the thermal and hydrolytic stability of hexaphenylcyclo-trisilazane is much higher than that of hexamethylcyclotrisilazane. By using a polar solvent, such as 1,4-dioxane,etc., hexaphenylcyclo-trisilazane trilithium salt is prepared through the reaction of hexaphenylcycoltrisilazane and n-BuLi at low temperature. Ring-opening polymerization of cyclosioloxane using hexaphenylcyclotrisilazane trilithium salt as a catalyst and THF,Diglyme of DMSO as a promoter is carried out. The polymer is characterized by 1H-NMR,29Si-NMr,GPC limiting viscosity number measurement. Nitrogen content of the polymer is determined by means of coulometric titration. It is confirmed hat the polymer contains hexaphenylclotrisilazane. The relation between the weight-average molecular weight and the limiting viscosity number of the polymer has been studied.
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发布时间：2021-03-19 - 摘要：Poly(3-hydroxyalkanoates),abbreviated as PHAs are a series of bacterial storage polyesters,currently receiving much attention because of their potential application as biodegradable,biocompatible materials.This paper studied the influence of glucose as the carbon source,nitrogen source,and phosphate on the structure of polymer synthesized by DG17,a mutant isolated from oilfield.The structure of polymer was determined by gas chromatograph(GC),nuclear magnetic resonance(NMR) analysis.Under the experimental conditions,a thermoplastic elastomer P(MO-co-HD) with molecular weight 1.16×105 was synthesized when concentration of ammonium sulfate were not over 1g/L.But thermoplastics PHB was isolated from cells when concentration of ammonium sulfate was up to 8g/L. During these two concentrations, no polymer was found in cells. Concentrations of nitrogen and phosphate maybe have great influence on the pathway of PHA synthesis. 5 was the lowest weight ratio of glucose to ammonium sulfate needed for DG17 to accumulated PHA in cells. Both P(HO-co-HD) and PHB synthesized by DG17 from glucose lost up to 90% weights in activated sludge in one month.
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发布时间：2021-03-19 - 摘要：Fluorosilicones are less stable than conventional methyl silicones because they are more likely to revert to low molecular weight cyclic products,especially in sealed circumstance.As for RTV fluorosilicone rubbers,they are usually vulcanized by ethyl silicate and diethylene diamine,and liable to suffer from reversion by water and catalyst and alcohol byproducts emit during vulcanization.Instead of ethyl silicate,one RTV fluorosilicone rubber was prepaired by using polysilazane KH-CL as crosslinking agent without using diethlene diamine as catalyst. The thermal stability of fluoroislicone rubber crosslinked by KH-CL(FSi-B) was compared with fluorosilicone rubber crosslinked by ethyl silicate and diethylene diamine (FSi-A)in sealed circumstance by TG、IGA and solubility. The results showed that FSi-B was such more stable than FSi-A due to eliminating water and siloxy that can lead to reversion of fluorosilicone rubber.
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发布时间：2021-03-19 - 摘要：Startch-graft-(VAc-co-MMA) copolymer was synthesized by graft copolymeri-zation of starch with VAc and MMA using Ce(Ⅳ) salt as initiator and water as reaction medium. 1H NMR technique was employed to study the composition of the graft chain,poly(VAc-co-MMA).The results show that the composition of the two monomer units in the graft chain varies slightly with the variation of the mole ratio of MMA to VAc in the feed.The mole ratio of the two monomer units in the copolymer is nearly 1.X-ray diffraction measurement indicates that the crystal structure of starch was greatly destroyed after graft copolymerization. The biodegradation behavior of the starch graft copolymer and the graft chain were investigated through enzyme attack in the laboratory and outaoor soil burial. In the laboratory,at 37℃,in the presence of bacillus subtilis,the grafted starch demonstrated arapid biodegradation rate.The weight loss was 15% after one day and reached a maximum of 66% after 25 days.This value is very close to the starch content(67%) in the specimen.The biodegradation at room temperature was also studied. The results show that at room temperature,the biodegradation rate is a little lower than that at 37℃.Further study indicates that the biodegradation originated from starch,the graft hain nearly unaffected by the bacillus subtitilis.After20 days outdoor soil burial in summer,the weight loss was 42%,demonstrated a nedrlly equal degradation rate compared with enzyme degradation in the laboratory at room temperature (that is 44% after 20days).
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发布时间：2021-03-19 - 摘要：Atom transfer radical polymerization (ATRP) of n-butyl methacrylates (BMA) has been achieved with ethyl 2-bromoisobutyrate [(CH3)2CBrCO2C2H5] as an initiator and CuBr,2,2′-bipyridine(bpy) and aluminum triisopropoxide [Al(OiPr)3] as a ternary catalyst system in cyclohexanone.The kinetics and mechanism of polymerization were discussed in detail.Al(OiPr)3,a bulky Lewis acid,which is used as a catalytic promoter,may coordinate the ester carbonyl of the initiator and polymer and activate the carbon-bromine bond.Therefore,BMA can be polymerized at a lower temperature.The influence of Al(OiPr)3 on polymerization rate and molecular weight distributions were also studied.The polymerization of BMA became sloer and more controlled with CuBr2 than without CuBr2 In the absence of CuBr2,the polymerization of BMA were the rapider and less controlled at 28℃ In the presence of CuBr2,the polymers produced at 52℃ had narrow molecular weight distributions (MWD=1.2～1.5) and designed molecular weights which were nearly proportional to mononer conversion.The logarithmic conversion data plotted against time (ln([M]0/[M]) versus time) followed a current first order kinetics.
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发布时间：2021-03-19 - 摘要：The poly(methyl acrylate-co-itaconic anhydride)/silica hybrid materials were prepared from methyl acrylate -itaconic anhydride copolymer and tetraethoxysilane (TEOS) with the coupling agent (3-aminopropyl)triethoxysilane (APTES) via sol-gel process.The triethoxysilane-bearing polymer was prepared by the in-situ aminolysis reaction of the amino group on APTES and the unit of itaconic anhydride.By the sol gel process of TEOS and the triethoxysilane,the covalent bonds between organic and inorganic phases were introduced.The proof of this process was provided by FTIR analysis. The gel-time and sol-fraction decreased as the amount of APTES increased.DSC showed that the glass transition of the hybrids was leveled by the use of APTES and at last disappeared.From the photographs of SEM we can see that when APTES was absent there was phase-separation.In contrast to this,inthe presence of APTES,no phase separtion was observed.
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发布时间：2021-03-19 - 摘要：The intrinsic viscostiy of terpolymers of acrylic acid (AA),acrylamide,and methacryloloxyethyl trimethylammonium chloride (DMC) in aqueous sholution of different added salts has been determined by the method of dilution in constrant concentration of added salts. The experimental results show that all terpooymers display trypical ordinary polyelectrolyte viscosity behavior in different concentration of NaCl solution and NaNO3 solution while the terpolymers with approximate balanced stoichiometry display typical polyampholyte viscosity behavior in different conentration of Na2SO4 solution. Effects of different added salts on the intrinsic viscosity of terooymers solution are inthe order:Na2SO4>CaCl2,NaNO3>NaCl
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发布时间：2021-03-19 - 摘要：The water absorption dynamic mechanical properties and dielectric properties of cured epoxy resins with different active esters were investigated. It was found that the water absorption of cured epoxy resins is influenced by the structure of the esters used and the ester groups on side chanis inhibit the water molecules to enter the resin matrix. It was shown also that the dynamic mechanical and dielectric properties of the cured epoxy resins with active ester are improved due to the increase of moisture resin matrix. It was shown also that the dynamic mechanical and dielectric properties of the cured epoxy resins with active ester are improved due to the increase of moisture resistance of the resins.
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发布时间：2021-03-19
Research Article
- 摘要：The ethylene homopolymerization with new MgCl2supported bimetallic complex catalysts Ti(OBu)Cl3Et(Ind)2ZrCl2 and Ti(OBu)Cl3/Cp2ZrCl2 was studied.The catalyst systems show high activity and the polyethylene with broad molecular weight distribution(MWD) was produced.The MgCl2-supported bimetallic complex catalysts contain traditional Z-N catalyst and movel metallocenes.Two active sites of Ti and Zr have different chain propagation,transfer,termination rate constant of olefin polymerization can be regulated easily by varying polymerzation conditions for improved processability and mechanical properties. Moleclar weight,molecular weight distribution, Tm and crystallinity were measured by GPC and DSC.
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发布时间：2021-03-19 - 摘要：The coarsening process of the droplets in two-phase polymer blend system was studied under 2-dimensional conditions using a phase contrast microscope and computer image analyzer.It was found that the substrate (glass) has significant effect on the phase separation and droplets coarsening process.The interfacial interaction(wetting effects)will accelerate the droplets coarsening process when one phase has stronger affinity to the substrate than another phase,and the growth of the droplets radius with time follows r3～taa>1. On the other hand,when there is almost the same interaction between the dispersed phase and the matrix with the substrate,i.e. the two phases have the same wettability to the substrate (such as the system of PP/PE),no effect of the substrate on the coarsening process of the droplets was observed,i.e.the growth law is r3～t according to Ostwald ripening theory. It is expected that there is a critical value for the interfacial tension between the components of blends under 2-D condition.The growth law of the dispersed phase changes-over above or below the critical point.
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发布时间：2021-03-19 - 摘要：C60-end-bonded polystryrenes(PS-C60-Br) with narrow molecular weight polydispersity were prepared by atom transfer radical polymerization (ATRP) in good yield.GPC results show that the polydispersities of these fullerene polymeric derivatives were between 1.1 and 1.3.The brown color of the solution indicates that C60 has been bonded into the polymer,which was confirm by UV-vis.Furthermore,2-amino-acetonictrile was used as an IR label to react with PS-C60-Br,and the product show the characteristic absorption of CN GROUP AT 2369cm-1.These results reinforce the conclusion that C60 has been covalently bonded into the polymer.A polssible mechanism of the formation of C60-end-bonded PSt was deduced tentatively.
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发布时间：2021-03-19 - 摘要：A series of tri-component copolyesters composed of glycolide/lactide/caprolactone (PGLC) were obtained by bulk ring-opening copolymerization of glycolide(GA),L-lactide (L-LA) and caprolactone(CL) with Sn(Oct)2 as catalyst for the purpose of biomedical applications.Structure of the PGLC copolyester was characterized by means of GPC,1H-NMR,DSC and X-ray diffractometry techniques.It was found that the obtained polymer was a pure copolymer that consisting of no other side-produced polymers and the copolyester was a random copolymer that presented an amorphous struture in a large range of composition. The hydrophilicity and degradation rate of the copolyester were also studied in detail and it was found that the hydrophilicity and hydrolysis rate were improved by measuring the tensile strength and the elongation at break.The elongation of the copolyestercould be improved by introducing CL to the PLGA.That the PGLC copolyester was a potential biomedical material was suggested.
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发布时间：2021-03-19 - 摘要：The liquid crystalline copolyester (LCP)/montmorillonite nanocomposites were prepared by polycondensation of terephthalic acid, p-acetoxy benzoic acid and 1,2-diacetoxy benzene,in the presence of an organically modified montmorillonite(OMt) with p-aminobenzoic acid hydrochloride.The cleavage effect of OMt and the liquid-crystalline behavior of the composites were described. The cleavage effect of OMt was examined by X-ray diffraction (XRD) and transmission electron microscopy (TEM).Room-temperature XRD spectra were collected from 20=2°to 20=10°.The eventual disappearance of any distinct X-ray diffraction peaks for the hybrid containing 2,3,or 5wt% OMt indicated the well dispersion of its original layer structure. The TEM micrograph showed that the silicate layer spacings were greater than 3nm,even some layers dispersed in polymer matrix individually. The glass transition temperature Tg of the LCP/OMt nanocomposites increased slightly as compared with the pure polymer,but the isotropic temperatues Ti decreased moresignificantly as the content of OMt increased.As the clay content increased up to 3%,the decrease of Ti reached 25℃ LCP chains separated in certain degree by inorganic phase decreased the ordering ability of mesogenic units.This may be the principal reason for the descent of Ti. The nematic texture of nanocomposites was observed by POM,and the schlieren texture became indistinct as the clay content increased.Although the schileren texture in POM for the hybrid with clay content up to 5% still could be observed,the evident location of disinclination point already can't be found.Thus,the mechanism of disinclination in nematic phase for LCP hybrid with OMt is more complicated thean that for pure polymer.
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发布时间：2021-03-19 - 摘要：The multilayer films from diazoresin (DR) and poly(sodium acrylate, PANa) or alkali hydrolytic maleic anhydride/styrene copolymer (PMSNa) were fabricated on mica. During the fabrication process the absorbance increases about 0.033 for every fabrication cycle, indicating that the thickness of the film increases regularly. Under irradiation of UV light or heating, following the -N2+ decomposition, the inoic bond of the film converts to covalent bond. The morphologies of the film after DMF etching for the different films (irradiatied or unirradiated etc) were observed by Atomic Force Microscopy (AFM) and the result shows that the ability of the film against etching from polar solvent increases obviously.The conversion of bond nature from inonic to covalent was verified preliminarily by FTIR spectral analsis.
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发布时间：2021-03-19
Research Bulletin
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