最新刊期
卷 ， 期 1 ， 2006
- 摘要：Segmented polyurethanes,Poly(hexamethylene adipate)／liquified 4,4'-methylenedi(phenylisoeyanate) (L-MDI)／butanediol(PHMA／L-MDI／BDO)were prepared by a two-step process．and their structure and shape memory effect were investigated by DSC、WAXD testing．the tensile mechanical．dynamical mechanical properties were discussed also in this paper．It was found that the hard segment regions of these PUs were amorphous．and the soft segment ones were crystalline．The samples exhibited obvious shape memory behavior with shape recovery temperature around 35—45℃．The strain fxity was close to 100％．and the maximum shape recovery rate was mole than 97％．The sample showed high tensile strength,28—50 MPa,and large elongation at break,900％～1400％,aI room temperature．Dynamic mechanical tests indicated that the modulus at room temperature was about 140 times as high as that in the rubbery platean region．it shown an excellent dynamical property．
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发布时间：2021-03-19 - 摘要：A method was applied to form erosslinking networks in the ethylene—propylene-diene terpolymer(EPDM) grafting maleic anhvdride(EPDM-g—MAH)matrix with calcium carbonate(CaCO3)particles．The tensile test showed that the tensile strength and the elongation at break of the EPDM—g—MAH／CaCO3 composites were improved significantly,and when the content of CaCO3 was about 20 wt％in the composites,the maximum tensile properties were achieved．The results of swelling and solution tests showed that the composites had formed evident erosslinking structure．The results of ATR—FTIR spectrum and TGA showed that the acid-base reaction between CaCO3 and MAH had nnurred.
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发布时间：2021-03-19 - 摘要：The Bioresorbable nanofiber mats of poly(1actide-CO-glycolide)／β-tricalcium phosphate composites (PLGA／β-TCP)were eleetrospun．The effects of the most important processing parametem including PLGA solution concentration,β-TCP／PLGA weight ratio,feed rate,voltage,and distance between the tip and the receiver on the composite nanofiber mats were investigated in detail．Then,the composite nanofiber mats were characterized by scanning electron microscopy(SEM),TEM(transmission electron microscopy)and tensile tester．The SEM images showed that the diameters of PLGA／β-TCP nanofibers were inereased with the increasing of the concentration of PLGA and feed rate．The resuIts of tensile tests revealed that the tensile strength and Young’S modulus of the composite nanofiber mats were lowered with increasing the content ofβ-TCP．
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发布时间：2021-03-19 - 摘要：The lyotropie liquid crystallinity of two low molecular weJisht chitosan samples prepared by enzymic decomposition was investigated．The number averge molecular masses of those two samples CSl and CS2 were 622 and 231 l g／m01．measured by means of GPC and MS．ne lyotropic liquid crystalline behavior was found for these samDles eyen when the molecular mass was as low as 622 g／mol(～tetramer)．The critical concentration of CSl and CS2 to form liquid crystalline phase was determined to be 73 wt％and 36 wt％respectively．The results agree with the Drincipie rule deduced from chitosans with high and medium molecular mass,which states tllat山e critical concentration increases with the decrease of molecular mass．However the resuhs were not aceordant with those Dredietd by the traditional Khokhlov．Semenov(KS)theory,because山e molecular lnass of the samples is out of the region in which KS theory can be used．
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发布时间：2021-03-19 - 摘要：The system of bisphenol-A diglyeidyl ether type epoxy resin(DGEBA)cured with 2-ethyl-4- methylimidazole(2,4-EMI)was studied by means of differential scanning ealorimetry (DSC)in isothermal mode．Analysis of DSC cures indicated that the curing reaction could be separated into two stages,the addition reaction and the catalytic polymerization,as proposed in the literatures．The catalytic polymerization reaction has an induction period which decreases with the increasing of curing temperature(Tc)．The rate constants for the catalytic polymerization stage Were calculated from DSC studies．A curing kinetic model separated into two steps by the induction period was developed based on the reaction mechanism．The model can predict part of the experimental results．but some deviations are observed at the higher values of curing degree(α)．A critical value of curing degree (α)and a diffusion factor were introduced,and a diffusion controlled curing kinetic model was developed．For the systems of various concentrations of 2,4-EMI cured in the temperature range of 90～120℃,the values of αcwere calculated．The studies show that the diffusion factors affect the curing kinetics greatly in the higher values of α．When the valHe of α is lOW,the reaction is controlled by the chemical factors,but it is eontrolled by diffusion,when α is high．The value of αcis mainly affected by the glass transition of the system．With the increase of Tc,the curing degree at the glass transition increases and thus the value of αcincreases too．
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发布时间：2021-03-19 - 摘要：A series of water-soluble comb-like copolymers poly(acrylic acid)-g-poly[(ethylene glycol)methyl ether](PAA-g-mPEG)were synthesized by free-radical copolymerization of acrylic acid and mPEG monoacrylate macromonomers in iso-propanol solutions．The macromonomer was prepared by acrylation of monomethoxy poly(ethylene glycol)with aecrJoyl chloride．The characterization of the macromonomer and these copolymers was carried out by Fourier transform infra—red(FT—IR)and nuclear magnetic resonance(1H-NMR)spectroscopy．The glass transition temperature and melting temperature of the mPEG side—chains were detected by using DSC．It was found that the shorter the side chains,the higher the Tg is,and the mPEG side—chains in the copolymer could crystallize from the solution,but not easily from the melt．It implies that the movement of the side chains is strongly confined by the backbone and depends on the side chains length．Furthermore,the crystalline and phase morphologies of the comb—like copolymer films prepared by means of spin—coating on glass substrates were observed by phase contrast microscope and AFM. A lot of interesting crystalline and phase morphologies were found in the PAA—g—mPEG films．
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发布时间：2021-03-19 - 摘要：The mechanism of formation of polyamidoamine(PAMAM)dendrimer-methotrexate(MTX)complex and the release behaviors of MTX from the complex have been investigated．1H-,13C-NMR data confirmed that the formation of PAMAM-MTX complex was due to the interaction between PAMAM external amino groups and the MTX carboxyl groups．The PAMAM-MTX complex was stable in 10 mmol／L,pH 7．4 tris-HCl buffer solution．However．with increasing the ionic strength in the buffer solution,it Was easier for MTX to escape from the complex．which suggested that the interactiOn between PAMAM and MTX was electrostatiC in nature．UV results demonstrated that the hisher the generation of PAMAM,the greater its capacity to carry MTX molecules,e．g．G．5．0 PAMAM and G4．0 PAMAM could load 27 and 14 MTX molecules．respectively.
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发布时间：2021-03-19 - 摘要：Polybutadiene／montmorillonite nanocomposites(NC)were prepared by in situ anionic polymerization·The effects of treating method of OMMT,the kinds of OMMT and solvent on polymerization were studied．The structure and propenies of the nanoeomposites were characterized by using XRD,TEM,HNMR,DSC,TGA and DMA-A two times change of Buli wastage was found for OMMTs treated by different methods．The NCs had wide molecular weight distribution．when OMMT-DKI was added,whereas the NCs had narrow molecular weight distribution when OMMT-DKlB and OMMT—DK4 were added．The OMMT was soluble in toluene and xylene,but didn’t dissolve in cyclohexane．XRD and TEM showed that the exfoliated nanocomposites were prepared by the in situ anionic polymerization．From the H—NMR spectra of polybutadiene(PB)and PB/OMMT nanoeomposites,micmstucture changes of PB were found．The 1,2 unit content of PB increased approximately 100％,when 6．2 wt％of OMMT was added．The results of DSC and DMA indicated that Tgand Tdc were increased approximately 10 K and 16 K,respectively,when 6．2 wt％of OMMT was added．Both the storage and loss moduli increased with OMMT addition,and tan δvalues decreased．
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发布时间：2021-03-19 - 摘要：Dynamic vulcanized NR/PP/nano-silica blended thermoplastic elastomer(TPE)was prepared．The effects of the modification of nano-silica and MAH／St／DCP multi-monomer melt grafting and cross—linking on the mechanical properties,the resistance to solvent and resistance to thermal distortion of TPE were investigated．SEM was used to stuay the morphology structure of TPE．The results showed that．the MAH／St／DCP multi—monomer melt grafted and cross—linked TPE had the best mechanical properties．resistance to solvent and resistance to termal distortion．when the mass ratio of nano-silica was 0．03 and that of MAH/St/DCP was 0．0375／0．0188／0．00375．The compatibility and inteffacial interaction between NR and PP were increased greatly by thinning the dispersive phase, improving the dispersion uniformity of NR and enhancing the co-cross-linking of the two phases．The comprehensive properties of NR/PP TPE were improved obviously．
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发布时间：2021-03-19 - 摘要：Electrospinning has been recognized as an efficient method for fabricating continuous nanofibers for,e．g．,biomedical applications．With a modified CO-axial electrospinning technique,a pencil-like,core-shell composite nanofiber can be obtained．In this paper,two pure drugs,resveratrol and gentamycin sulfate,were encapsulated respectively into the cores of biodegradable polycaprolactone(PCL)uhrafine fibers with a diameter down to hundreds of nanometers．The fabrication process of these nanofibers and their micro-structural characteristics were investigated．Such composite nanofibers can be useful in controlled drug release and in the development of new medical devices as absorbable sutures inside human body or wound dressing materials．
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发布时间：2021-03-19 - 摘要：High-density polyethylene／elastomer／calcium carbonate ternary composites with dispersed phase of calcium carbonate as a core and maleated elastomer(ethylene—octane copolymer)POEg as a shell were prepared through the reactive extrusion．The improvement of impact strength of HDPE／POEg was limited due to the high miscibility between them．The introduction of CaCO3 had a negative impact on the toushness of the HDPE matrix because of the poor interfacial adhesion．However,in these ternary composites,the calcium carbonate and elastomer showed synergistical toughening effects on the HDPE matrix as a result of the formation of core—shell structures due to the strong interaction between POEg and CaCO3,which improved the HDPE—CaCO3 interfacial strength and the toughness 0f the blends．The brittle-ductile transition occurred at lower contents of POEg for surface treated calcium carbouate based ternary composites compared with the untreated calcium carbonate based ones．
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发布时间：2021-03-19 - 摘要：PS／CaCO3 composite nanoparticles with nanometer CaCO3 particles as the core and cross-linked PS as the shell were prepared by emulsion copolymerization of styrene and multivinyl monomer as crosslinker in the presence of stearic acid coated nanometer CaCO3 particles．The effects of the type and amount of multivinyl monomer,the amount of CaCO3 on polymerization reaction and encapsulation were investigated．The results show that the introducing of multivinyl monomer and CaCO3 can slow down polymerization rate to different extent．Using 1％～5％ trimethylolpropane trimetbacrylate(TMPTMA)or divinyl benzene(DVB),tight encapsulation of CaCO3 can be realized and beyond 94％PS cannot be extracted. The amount of crosslinker or emulsifier should be accommodated when the load amount of CaCO3 is increased．CaCO3 content in the product increases consequently with the increase of the loaded amount of CaCO3,which can be known from FT-IR and TGA．TEM observations reveal that when the load amount of CaCO3 is 14．8％,most CaCO3 particles are encapsulated and each latex particle contains one CaCO3 particle．Composite particles have well-defined core—shell structure and the thickness of polymer shells is around 10 nm．However,the thickness of polymer shell decreases and many free CaCO3 particles appear when the load amount of CaCO3 reaches 29．3％and 58．7％,respectively．
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发布时间：2021-03-19 - 摘要：Three gelatins with α component content 20．5％,41％and 50％,respectively,were used as raw materials for the preparation of gelatin／hydroxyapatite composites by simultaneous titration method,and then the tensile properties for dryfilms of the three composites,includingtensile strength,Young’ modulus and elongation at break,were measured and compared．The results showed that all of the three tensile parameters increased with increasing the α component content of gelatins．Among them,the Young’s modulus of composites was more sensitive to the α component content of gelatins．The mechanical properties of composite C with the hishest α component content were shown as follows：86．40 MPa of tensile strength．2682．35 MPa of Young’s modulus and 8．65％of elongation at break．In addition,the characterization results of basic properties of composite C revealed that this material had the composition and structure similar to those of natural bones,and therefore was promising to be a good candidate for bone substitute materials.
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发布时间：2021-03-19 - 摘要：The adsorption isotherm of polyethyleneimine(PEI) modified diatomite was studied using UV spectrophotometry．The surface of diatomite was modified with polyethyleneimine by using impregnation method,and the trapping behavior of the modified diatomite for phend was investigated by using 4-aminoantipyrine method．The experiment results showed that negatively charged diatomite particles had very strong adsorption effect for cationic macromolecules of PEI,and it was attributed to the strong electrostatic interaction．The adsorption isotherm fits the Freundlich equation．After modification,the electric properties On the surface of diatomite particles changed factually,and the isoelectrie point moved from pH=2．0 to pH=10．5．In acidic solutions,phenol exists as molecules,and the modified particles adsorb phenol throush hydrogen bonding interaction．However the hydrogen bonding interaction between nitrogen atoms on PEI chains and phenol is weak because of the high degree of protonation of polyethyleneimine macromolecules,so the adsorption quantity is low．In basic solutions,phenol exists as phenoxy anions,and the modified particles adsorb phenol through electrostatic interaction．However the electrostatic interaction between PEI and phenoxy anions is very weak owing to the low degree of protonation of polyethyleneimine macromoleeules,so the adsorption quantity is much lower．The modified particles exhibit very strong trapping effect for phenal through the cooperation of strong electrostatic interaction with hydrogen bond effect in neutral solutions,and the saturated adsorption capacity can be as high as 92 mg/g．
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发布时间：2021-03-19 - 摘要：In aqueous solutions of sodium polystyrene sulfonate(PSS)the different degree of neutralization is realized by electrostatic interaction with cationic surfactants(cetyltrimethylammonium chloride(CTAB)or didodecyldimethylammonium bromide(DDAB))added．The aggregation behavior of adducts of PSS and cationic suffactants with different degree of neutralization(DN)is studied by several methods in aqueous solution,such as the transmittance measurements,the fluorescence spectrum,fluorescence probe and the observation of scanning electron microscopy．The results indicate that PSS-CTAB(DDAB)nano—particles with a diameter of about 70 nm could be synthesized and possess hydrophilie shell and loose hydrophobic core into which the pyrene molecules can enter.
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发布时间：2021-03-19 - 摘要：The mechanism of piezoresistive behavior and the improvement of its stabilitv for high—density polyethylene／carbon black(HDPE／CB)composites were studied．The results revealed that the uniaxial piezoresistive behavior resulted from the change in the structure of the percolation network,depending on the filler volume fraction ψand the deformation of the material under pressure．When ψ approached the percolation threshold ψc,with increasing extemal pressure the composites exhibited a positive pressure coefficient(PPC) effect for its resistance．In the ease of ψ far beyond theψc,only a negative pressure oefficient(NPC)effect for its resistance can be obsered．The resistance baseline at zero pressure after unloading shifted upward or downward with the increase of the numbers of compressive cycles,depending on the ψ．The shift of the baseline was related with the residual compressive strain and carl be stabilized by increasing the number of the compressive cycles．Crosslinking of the matrix can restrict the residual compressive strain and stabilize the baseline shift of the resistance-time curve,especially for the composites with a highψ．
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发布时间：2021-03-19 - 摘要：The transesterification reaction among poly(ethylene terephthalate)(PET),poly(ethylene 2,6- naphthalate)(PEN),and PET／PEN copolymer were studied with1H-NMR．The rate constant k,the activation energy．and induction period of the transestetifieation reaction for the PET/PEN reactive blend were obtained using a kinetic expression based on a second-order reversible reaction mechanism．The relationship between transesterification and miseibility was discussed on transesterification level and induction period．It was found that miscibility of PET and PEN blends leads to or enhance transesterification,that iS,miscibility is a necessary condition for transesterification in the polyester blends：transesterification accelerates miscibility of PET and PEN blends．Both events are interrelated in the molten state of polyester blends．
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发布时间：2021-03-19 - 摘要：The comb-shaped copolymers PAn-g—PEG were prepared by chemical oxidation copolymerization of aniline and methoxyl poly(ethylane glycol)o-aminophenyl ether．The UV-visible spectra,microstructures,thermal stabilities．solubility and film-forming properties of the copolymers were investigated as functions of side-chain poly(ethylene glycol)(PEG)segments．The results show that when the PEG segments length or its content in the grafted copolymers are increased,the solubility and film-forming property of PAn—g—PEG improve remarkably,and the electrical conductivity decreases slowly,while the thermal stability becomes worse．TEM images indicate that the copolymers exhibit microphase separation and morphology change from the“sea-island’’mode to the"bicontinuous”one with increasing the length or content of the PEG segments．A soft and smooth conducting polymeric film ean be directly obtained by casting the stable aqueous dispersion of PAn—g—PEG,which becomes water-soluble when the PEG segments length or content are increased．
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发布时间：2021-03-19 - 摘要：Thermoplastic acetylated starch(TPAS)was prepared with acetylatad starch as matrix and glycerol as plasticizer by Haake Rheomix．Experimental results showed that the weight ratio of glycerol／acetylated starch should exceed 30/100 for obtaining TPAS,and the brittleness of TPAS decreased with increasing glycerol content．Dynamic mechanical thermal analysis(DMTA)indicated that acetylated starch and glycerol were partially miscible with separated aeetylated．starch—rich phase and glycerol—rich phase．The rheological properties of TPAS exhibited solid—like behavior．indicating the strong interaction among the acetylated starch molecules．In addition,the thermal stability of TPAS was also investigated in this paper．
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发布时间：2021-03-19 - 摘要：The composites of thennotropic liquid crystalline copolyesters((p-hydroxy benzoic acid)一terephthalic acid-resorcin)(HB-TA-RES)and poly(butylene terephthalate)-poly(tetramethylene glycol)thermoplastic elastomer (PBT-PTMG)with different copolyester content or copolyester composition were prepared by in-situ polycondensation method．The obtained(HB—TA—RES)／PBT-PTMG were characterized by POM,TGA,WAXD,SEM and rheological analysis．Liquid crystalline behavior of the composites was observed when the HB content in copolyester was 40 mol％ and copolyester content in composite was 30 wt％～70 wt％ or copolyester content in composite was around 50 wt％and HB content in copolyester was 20 mol％～80 mol％．When the copolyester content in composites≤50 wt％or HB content in copolyester≤60 mol％,no obvious phase separation happened．The molecular structure of copolyester in composites was more homogeneous and the crystallization of HB was limited．The good thermal stability of(HB—TA—RES)／PBT-PTMG composites with thermotropic liquid crystalline behavior was obtained as compared with the corresponding homocopolyester and the viscosity of the composites was lower than that of the matrix PBT-PTMG especially when the copolyester content was more than 30 wt％．Good processability of the composite is expected in the application．
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发布时间：2021-03-19 - 摘要：A series of blends with varies compositions was prepared by melt—mixing on the basis of poly- (phthalazinone ether sulfone ketone)(PPESK)and poly(ether sulfone)(PES)．The thermal stability of PPESK／PES blends was characterized by kinetic studies using dynamic thermogravity in nitrogen atmosphere．The dynamic mechanical properties of blends were carried out with DMTA. The results showed that the thermal degradation displayed a two—step reaction and the degradation of PPESK Was found to be a first order reaction in nitrogen．It suggested that the degradation of PPESK in nitrogen was just related with the material properties not with the rate of temperature increasing．The dynamic data such as the apparent activation energy before 15％ loss mass,Ea of 240 kJ／mol．were analyzed using Ozawa method．The thermal degradation rate of PPESK was slowed with increasing heating rate．Besides,the storage modulus of PPESK decreased a little with temperature increasing before 280℃,however,it had a remark drop in the temperature range of 280℃ to 330 ℃．The presence of PES in PPESK resin reduced the storage modulus and thermal stability．
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发布时间：2021-03-19 - 摘要：Due to the high concentration,thicken color,great toxicity and bad degradation of the dye wastewater,its treatment is always a difficult subject．Attention has been paid to the application of porphyrin and PcS as photo-catalyst for wastewater treatmem．As a bionic compound,the structure of phthalocyanine sulfonic iron(FePcS)(likep-450)is similar to that of porphyrin modified metal．In this paper,A novel catalyst ofhypercrosslinked resin,named as C-FePcS,was synthesized by using the Friedel-Crafts reaction between FePcS and post-crosslinked beads of chloremethylated polyvinylbenzene-styrene．The catalyst was characterized by diffuse reflectance absorption spectra, and essential conditions of photo reaction were discussed Upon visible light irradiation in the presence of H2O2,this catalyst was found to be hishly effective for the degradation of nonbiodegradable malachite green(MG)in aqueous solutions with decolomess rate of near 100％and total organic carbon(TOC)removal rate of 72％．The influence factors of degradation of MG with visible light at different conditions including acidity,dosage of catalyst were investigated．This catalyst was hardly affected by pH of the solution．A possible reaction mechanism was also proposed．
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发布时间：2021-03-19 - 摘要：The photo-induced eopotymerization of methyl acrylate(MA,M1)and 4-acrylamido-2,2,6,6- tetramethyl—piperidine(AATP,M2)in pyridine solutions was studied．The composition of MA and AATP copolymers was determined with1H-NMR method．According to the composition of poly(MA—CO—AATP),the reactivity ratios of MA／AATP copolymerization system were calculated as 0．88121=0．90 and r2=0．50 by the extended Kelen-Tudos method．The results showed that the reactivity ratios of both MA and AATP monomer were less than 1,as r12f1=0．73．On the basis of the reactivity ratios of two monomers,the sequence-length distribution in the MA／AATP copolymers was obtained．Forf2=O．7,the probability of the MA sequence of 1 unit in the copolymer chain is 80．0％,the monomer unit of MA is mostly separated by the sequence of AATP；and for f2=0.5,the alternating tendency prevails and a large number of mono—sequences are formed；and in the case of f2=0．1,the probability of the AATP sequence of 1 unit in the eopolymer chain is 95．0％,the monomer unit of AATP is individually separated in tlle chain of MA．
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发布时间：2021-03-19 - 摘要：Poly(ethyl glycol)-b-poly(L-phenylalanine)AB dibloek copolypeptides(MPEG44一b—Phe50 and MPEG44-b-Phe7)were synthesized from Phe-NCA monomer by using α-methoxy-ω-2-aminoethyl-poly(ethylene glycol)(MPEG-NH2)as the initiator．L-phenylalanine N—carboxyanhydride(b-Phe—NCA)was prepared with the phosgene method(Fuehs-Farthing method),through the reaction of amino acids and triphosgene．The macromoleculeas initiator,amino-terminated(MPEG-NH2)was prepared by convening the end group of hydroxyl to amino group．The structure of these copolymers were characterized by means of FTIR、1H-NMR and GPC．The results of these experiments pmvided direct evidence of the formation of the block copolymers．Self-assembled structures of the synthesized diblock copolymers in water were prepared by the dialysis method and the morphologies of the aggregates were investigated by TEM．The results proved that these amphiphilic diblock copolymers Can self-assemble into micelles in water．
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发布时间：2021-03-19 - 摘要：Diformahriphenylamine and 1-methoxy-4-octoxyl-2,5-xylenebis(triphenyl phosphonium chloride)were synthesized,and their copolymer(TPA—MOPPV) was obtained through a Wittig polycondensation．The structures of the monomer and copolymer were characterized by FT-IR．UV-Vis．1H—NMR and fluorescence spectrum．The optical properties and thermal behavior were discussed in detml．A strong blue—greenish light,with 503 nm maximum wavelength,was observed for the copolymer in 0．01 g/L CHCl3 solution．Furthermore,concentrations on photoluminescence property of the polymer was investigated．The results showed that the maximum excitation wavelength was approximately 440 nm when the concentration of the copolymer was under 0．01 g／L．but the maximum excitation wavelength exceeded 492 nm after the concentration was above 0．01g/L．The copolymer is readily soluble in common organic solvents at room temperature,so it could be easy to prepare electroluminescent device by spin-coat technology．The electrochemical studies suggested the hole injection and hole transport properties could be improved because of introducing the triphenylamine units．Its electroluminescence properties were investigated．a polymer light emitting diode with the TPA—MOPPV as the active layer(ITO／PEDOT：PSS／TPA-MOPPV／Ba／Al)showed greenish yellow emission with luminance over 369 cd／m2 at 6 V and the low turn—on voltage (3．2 V),the maximum external quantum efficiency was 0．14％．DSC analysis showed that Tg of the polymer was 23 K higher than that of triphenylamine derivatives TPD,and the results of TG indicated that the decomposition temperature of TPA—MOPPV was 208℃ and the polymer did not displays apparent weight loss until 360℃．In a word,the polymer exhibits strong fluorescence,relatively hish thermal stability,good film—forming capability,high luminance,good hole—transporting property,being a good candidate of electroluminescent material．
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发布时间：2021-03-19 - 摘要：A narrow molecular weight distribution poly(D,L-lactide—cholester01)(LC)was synthesized by bulk polvmerization．The molecular weights of LC obtained from 1H-NMR and GPC were in good agreement with the theoretical values．which indicate that the LC molecular weight can be adjusted by varying the D,L-lactide／chalesterol ratio．The chondrocyte cell attachment,proliferation and 3-(4,5-dimethyhhiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide(M'IT)cell activity on LC and poly(D,L-latic acid)(PLA)were investigated．The results showed that LC exhibited improved cell attachment and significantly better proliferation compared with pure PLA．The confocal laser scanning microscopy(CLSM)images showed that the number of chondracytes on PLA films was 1ess than that on LC．The chondrocytes on LC are spreading uniformly and completely while the chondrocytes on PLA are clotted and not in a normal spreading status．A1l the results above demonstrate that cholesterol-containing materials can construct a chondrocyte compatible surface and may have potentials for cartilage tissue engineering and other biomedical applications．
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发布时间：2021-03-19 - 摘要：The performances of propylene polymerization with a TiCl4／MgCl2／9,9-bis(methoxymethyl)fluorine (BMMF)catalytic systenm in the absence of external donor were studied at various temperatures．The influences of alkylaluminiums were investigated．The results showed that i-Bu3Al and Hex3A1,which shewed weaker coordination and alkylation than Et3Al and Me3Al,resulted in higher activity and isospeeificity at lOO ℃．With Me3 Al the catalyst produced higher proportion of steroblock polypropylene than with other alkylaluminiums．The isotactic polypropylene obtained with Et3 Al contained ethylene units when the ratio of Al to Ti was 150 at 100℃．However,the isotaetie polypropylenes obtained with iBu3 Al and Hex3 Al at 100℃ did not contain isobutene and hexene units．
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发布时间：2021-03-19 - 摘要：The stable concentrated emulsions of methyl methacrylate—butyl acrylate(MMA—BA)are prepared using sodium dodecyl sulfate(SDS)and cetly alcohol(CA)as the compound surfactants,polyvinyl alcohol(PVA)as the reinforcer of liquid films．A novel method of polymerization,the thin layer copolymedzation of the concentrated emulsion,was carried out with benzoyl peroxide／N,N'-dimethyl aniline(BPO／DMA)as redox initiators at low temperature．Effects of categories of the reinforcer of liquid films and the polymerization environment on polymerization stability were introduced．The effect of the thickness and area of films,the outside temperature,and environment of polymerization on the amount of volatilization were investigated．The conversion comparison of the thin layer polymerization with the tube polymerization and the effect of polymerization environment on the polymerization rate were discussed also．The size and distribution of particle diameter and morphology of latex particles were determined with TEM.
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发布时间：2021-03-19 - 摘要：Graft copolymers of βpinene with methyl methacrylate(MMA),butyl acrylate (BA) or styrene(St) were synthesized by the combination of living cationic polymerization and atom transfer radical polymerization (ATRP)．β-Pinene polymers with predetermined molecular weights and narrow molecular weight distributions (MWDs)were prepared by living cationic polymerization with the 1-phenylethyl chloride／TiCl4／Ti(OiPr)4／nBu4NCl initiating system,and the obtained polymers were brominated quantitatively by N—bromosuccinamide in the presence of AIBN,yielding poly(β—pinene)macroinitiators with 50％ of bromine contents(Br/β-pinene unit molar ratio=0．5)．The macroinitiator,in conjunction with CuBr and 2,2'-bipyridine,was used to initiate ATRP grafting of BA．MMA and St．All of the grafting polymerizations induced linear first-order kinetic plots and gave graft copolymers with controlled molecular weights and MWDs,suggesting that these polymerizations are controllable．The structures of the obtained graft copolymers of β-pinene with(methyl)methacrylate or styrene were confirmed by 1H-NMR spectra．
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发布时间：2021-03-19
Research Article
- 摘要：Crylic acid and azobenzene containing acrylate copolymers PEAPH were fabricated into multilayers with their counterpart polyelectrolyte poly(diallyldimethylammonium chloride)(PDAC)in N,N'-dimethylformamide (DMF)using the layer-by-layer electrostatic adsorption technique The self-assembly of wator soluble and insoluble PEAPH in DMF was studied and compared．FTIR was used to detect the ionization of carboxyl acid of PEAPH during the assembling processes．All results show that both the water-soluble and water-insoluble PEAPH can be deposited with PDAC based on the electrostatic attraction instoad of other interactions．In assembling processes PEAPH molecules ate deposited in molecular level instoad of molecular aggregation and form a cross-linking muhilayer structure．Assembling media of DMF and water do not have obvious infiuence on the muhilayer structure．
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发布时间：2021-03-19 - 摘要：Uniformly imprinted polymer microspheres were prepared by precipitation polymerization in chloroform．MCP(monocrotophos),MAA(methacrylie acid),EGDMA(ethylene glycol dimethacrylate)and AIBN (azobisisobutyronitrile)were used as template,functional monomer,cross-linker and initiator,respectively．UV and IR spectra were used to demonstrate the mechanism of the interaction between MCP and MAA．It was found that one MCP was entrapped by three MAA molecules in chloroform．Langmuir model was used to fit the adsorption data,the results showed that the MCP imprinted polymer microspheros showed specific binding sites to the MCP．The data obtained in equilibrium adsorption experiments were processed by Seatehard analysis,the dissociation contents (KDl)and the apparent maximum binding capacity(Bmax1)were KDl=0．062mmol／L,Bmaxl=3．26μmol／g for high affinity binding sites and KD2=3．03 mmol／L,Bmax2=65．70μmol／g for low affinity binding sites,respectively．The MCP imprinted polymers have showed hisher affinity to MCP than to the other organophosphorus pesticide used．So the imprinted polymers mierospheres can be used for trace pesticide residue separation,enrichment and analysis．
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发布时间：2021-03-19 - 摘要：The carbocationic polymerization of styrene(St)initiated by H2O／TiCl4 system was conducted at-60℃ in dichloromethane(CH2Cl2)／hexane(n-Hex)(50／50 V／V)in the presence of pyridine(Py),2-methyl pyridine (Mry)and 2,6-dimethyl pyridine(DMPy)．A desirable polymerization process with a relative slow polymerization rate and PS products with relatively narrow molecular weight distribution(MWD,Mw／Mnca．1．8)were obtained．Py and its derivants and／or their complexes with Lewis acid TiCl4 interact with the growing chain end to reduced its “eationieity”and thus to decrease the polymerization rate,suppress chain transfer and termination reactions and narlow MWD．The experimental results also show that the monomer conversion as well as the molecular weisht of polymer products increased but MWD almost kept unchanged with polymerization time．The number-average molecular weight of polymer increased linearly with monomer conversion but the line did not pass through the origin．
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发布时间：2021-03-19 - 摘要：Fluoro-terminated hyperbranched poly(aryl ether ketone)(HPOP—PEEK—F)with 4-phenoxyphenyl side groups was prepared from A2(2-(4-phenoxyphenyl)-1,4-diphend)and B3(1,3,5-tris[4-(4-flourobenzoyl) phenoxy]benzene)with a function group ratio of 0．48：1(A2：B3)．The chemical structure of HPOP-PEEK—F was confirmed by FTIR and1H-NMR．The degree of branching(DB) of HPOP-PEEK—F was 0．66 determined by1H-NMR measurements．The phenyl ethynyl-terminated hyperbranched poly(ether ether ketone)(HPOP—PEEK-PEP) was prepared by the end—capping approach．The HPOP—PEEK—PEP showed high glass transition temperature than HPOP-PEEK-F,but exhibited lower thermal stability．After cross—linking,the glass transition temperature,thermal stability and anti-chemical eorrodibility of HPOP—PEEK—PEP were all improved.
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发布时间：2021-03-19 - 摘要：In order to enhance the reactivity of the silyl-containing ceramic precursor,a hyperbranched silyl— containing polymer with low viscosity and plenty of terminal vinyl—groups was prepared．A novel AB4,type monomer,bis(N,N—diallylamino)methylsilane,was synthesized first by aminolysis of MeHSiCl2 and then was polymerized via hydrosilylation reaction using H2PtCl6 as the catalyst.The polymerization process was monitored by FT-IR spectroscopy．The polymer product was purified via precipitation using ethyl ether and acetonitrile and was analysed by using 1H-NMR、29Si-NMR and FT-IR spectroscopy．The results indicated that the polymer was hyperbranched polycarbosilazane,and α-hydrosilylation was the main reaction．The degree of branching(DB)of the hyperbranched polymer was 0．56 calculated from the 29Si—NMR spectrum,and the average molecular weight(M)was 13 580 g／mol determined by fight scattering method．It was found that there still existed a lot offunctional vinyl end groups,which can be used as promising reaction centers for curing or modification of the polycarbosilazane．
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发布时间：2021-03-19 - 摘要：Two commercial ethylene—propylene random eopolymers(A and B)for hot water piping of which A has better long term heat stability and slow crack growth resistance performance than B were fraetionated with respect to the isotactitv distribution by preparative temperature-rising elution fractionation(TREF)．The molecular wetght and distribution of fractions and the original resins were investigated by gel permeation chromatography．The results indicated that both A and B had broad isotacticity distribution and A had fewer portions of high isotacticity than B．At the same time A had broader and more typical double—peak molecular weight distribution．The fractions of A had higher malecular weight and broader molecular weight distribution than those of B’s．All of these results implied the differences between the catalysts or the polymerization processes for the two copolymers．
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发布时间：2021-03-19 - 摘要：The calixarene crosslinked polysiloxanes were obtained by crosslinked N-(β-aminoetbyl)aminopropyl modified silicon oil with 1,3-diglycidyl calix[4]arcne．Their structures were characterized by infrared spectra and scanning electron microscopy．The thermal degradation behaviour of the calixarene crosslinked polysiloxanes with various content of calixaren under a nitrogen atmosphere was investigated by using thermogravimetry(TG),it showed that all the crosslinked polysiloxanes exhibited two-stage decomposition,the first decomposition peak was at about 391℃ and the second was at about 5200℃,the ratio of the two fastest weight loss rates was varied with the content of calixarene．Under our experimental conditions,the calixarene crosslinked polysiloxane with 3％content of calixarene had the lowest rate of degradation during the first stage of decomposition．The thermal stability of calixarene crosslinked polysiloxanes was enhanced compared with that of N-(β-aminoethyl)aminoprepyl modified silicon oil and 1,3-bis(2’,3'-epoxypropoxy)benzene crosslinked polysiloxane．
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发布时间：2021-03-19 - 摘要：The dispersion polymerization of St with PEO marcomonomer was successfully carried out with microwave irradiation．The morphology of the PSt-g-PEO mierospheres was characterized by TEM．The results showed that microspheres were spherical in shape with narrow distributions．The effects of St concentration,PEO macromonomer concentration．AIBN concentration,water content in the solvent and microwave power on the sizes of the PSt—g—PEO microspheres were investigated by Photon correlation spectroscopy(PCS)．Under the same microwave power,the sizes of the micrespheres were increased with increasing the initial St concentration and AIBN concentration；when the PEO macromonomer concentration and the water content in the solvent were higher,the smaller mierospheres could be prepared．For the same component ratio,the PSt-g—PEO microspheres prepared under microwave irradiation of 130 W were smaller than those prepared with irradiation of 195 W．
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发布时间：2021-03-19 - 摘要：n-Dodecylamine was used as reaction terminator to contrel the molecular structures of amine terminated hyperbranched poly(ester-amine)s(HPEA) synthesized from phthalicdiglycol diacrylate and 1-(2-aminoethyl) piperazine at molar ratio of 1：1 by Michael addition reaction．From the 1H-NMR spectra of HPEA．the degree of branching increased and the amino active hydmgen content decreased with prolonging the reaction time．HPEA Were further cured with β-glycidyloxylpropyl trimethoxysilane under ambient condition．The highest gel content and best mechanical properties of the cured coatings at active hydrogen and epoxy group stoichiometrie ratio of 1：1 Can be attributed to-the stepwise curing process,involving the fast reaction between amino active hyarogen and epoxy groups,and the slow hyarelysis and self-condensation of methoxysilane groups．
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发布时间：2021-03-19
Research Bulletin
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