最新刊期
卷 ， 期 9 ， 2007
- 摘要：Natural rubber (NR) degraded under high temperature and powerful shear force was in situ grafted onto the carbon black (CB) surface.The grafted carbon black (GCB) not only accelerates the vulcanization of NR composite,but also enhances the mechanical properties of vulcanized NR such as the tensile strength and the tear strength.The results of dynamical mechanical properties showed low degrees of CB aggregation in GCB filled NR system because of the better dispersion of GCB and the increased interaction between GCB and NR matrix.
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发布时间：2021-03-19 - 摘要：By means of a closely intermeshing twin-screw extruder as the reactor ,the mixture of styrene (S) and butadiene (B) as the monomer and THF as the polar catalyst,a copolymer (S/B) was synthesized by bulk polymerization with the organic lithium initiator.The PB chain of copolymers was cleaved by reaction with hydrogen peroxide in the presence of osmium tetraoxide,then the small molecules were removed out of the system by purification.The copolymers and the segments after oxidization were characterized by GPC cooperating with a multi-angle laser light scattering instrument (MALLS).It was found that the molecular weight distributions of the S/B copolymers were broadened,on the other hand,the molecular weights of the segments after oxidization decreased by addition of THF.The content of 1,2-PB was derived from 1H-NMR.It was confirmed that the content of 1,2-PB increased obviously as THF was stepped up,but to a great extent the trend of increasing was slow down.Cooperated with the survey of TEM photographs,it was confirmed that the phase of polybutadiene was minished by THF,and its distribution was more uniform.So it could be concluded that the basic mechanism of anionic polymerization during reactive extrusion was consistent with that in anionic solution polymerization,the difference only resulted from process factors during the reactive extrusion.
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发布时间：2021-03-19 - 摘要：The molten caprolactam was polymerized by means of anionic ring-opening polymerization in the presence of a non-crystallizable semi-aromatic polyamide copolymer (NSAP) in order to in situ fabricate the resultant polyamide 6 blends with NSAP.The in situ blends exhibit remarkably improved strength and modulus compared with those of the virgin system.The results of the characterization by using scanning electron microscope (SEM) and dynamic mechanical analyzer (DMA) reveal that there exist a homogeneous morphology and single glass transition for the blends.It is suggested that the miscibility results from the interchange reaction during polymerization.The traces of differential scanning calorimeter (DSC) demonstrate that as compared with the virgin system,both the melting temperature and crystallinity for the blends decrease.Wide-angle X-ray diffraction (WAXD) analysis shows that the crystals exist exclusively in α form for the virgin system; however,a drastic increase in the fraction of γ form appears in the in situ blends,e.g.,with the addition of 20 wt% NSAP,the majority of crystals is in γ form.However,only a slight refinement of spherulites occurs as observed by polarized optical microscope (POM).It is indicated that the improvement in the strength and modulus for the blends results from the reduction of molecule mobility and the fraction of PA6 γ crystals as well.
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发布时间：2021-03-19 - 摘要：Based on the Compass force field,the relationship between microstructure and macro-properties of carbon dioxide/propylene oxide/γ-butyrolactone tricopolymer (PPCG) was investigated by the`Materials Studio' simulation successfully.The results of simulation show that the molecular chains of PPCG are of flexible.Degradable carbonic and carboxylic ester groups were distributed outside the PPCG cell.Furthermore the structure of micro-phase separation was observed in PPCG cell.The reciprocity between PPCG and caffeine molecule was also simulated and calculated.It was found that the caffeine molecule was selectively distributed in CO2 habitat,but never in γ-butyrolactone (GBL) habitat.So the structure of micro-phase separation of PPCG can be applied in achieving the self-assembly of drug molecules,and the conclusion offers a theoretical base for the self-assemble behavior of drug molecule in this kind polymer carrier.The results of molecular simulation not only verified the experimental conclusions,but also showed a clear description about the relationships between molecular structure and macroscopic properties of PPCG.Moreover,it offered the theoretical base for further studying the reciprocity between carriers and drug molecules.
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发布时间：2021-03-19 - 摘要：The first-generation poly(amidoamine)(PAMAM) dendrimer was modified by the salicylaldehyde via a Schiff-base condensation reaction,and reacted with TiCl4·2THF to give rise to a novel dendrimer-supported titanium complex.Its architecture was determined by 1H-NMR,ICP-AES and ESI-MS.The application as a catalyst precursor,activated by methylaluminoxane (MAO),for ethylene polymerization was also carried out.The results revealed that the metallodendrimer catalyst for the polymerization of ethylene had a higher activity (56.56 kg PE/(mol Ti·h),at a ratio of Al/Ti=1000) in comparison with the corresponding phenoxy-imine complexes.The melting point temperature (Tm) of the polyethylene as determined by DSC was 138℃,and the crystallization temperature (Tc) was 116℃.The apparent molecular weight of the polyethylene(Mv) was 1.28×106 by viscometry.The results implied that these polymers were linear low-density polyethylene.The viscoelastic properties of the polyethylene also indicated that the polyethylene was of ultra high molecular weight.
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发布时间：2021-03-19 - 摘要：Some methods have been developed to convert the abundant,cheap CO2 resources to polymer products,in order to receive a degradable polymer by using CO2 as the raw material.A new aliphatic polycarbonate (PBCL) was synthesized by terpolymerization of carbon dioxide,1,2-butylene oxide(BO) and ε-caprolactone(CL).The terpolymer structure was characterized by FTIR,1H-NMR,13C-NMR,DSC and WAXD measurements.The influences of various reaction conditions such as the molar ratio of the monomers and the reaction time on the polymerization progress were investigated.The terpolymers were amorphous,the glass transition temperature (Tg) of the terpolymers were above 40℃,which were higher than those of poly(butylene carbonate) (PBC) and poly(ε-caprolactone)(PCL).The biodegradation behavior of these copolymers was investigated in a pH 7.4 phosphate buffer solution at 37℃.The results showed that ε-Caprolactone was inserted into the backbone of poly［(butylene oxide)-(carbon dioxide)］ successfully.ε-caprolactone offered an ester structure unit that gave the terpolymers remarkable degradability enhanced with increasing CL content in the terpolymers,the weight loss of PBCL55 was 37.68% after 8 weeks in buffer solution immersion test.
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发布时间：2021-03-19 - 摘要：5 Series of chiral-achiral N-propargylamide copolymers were synthesized,providing copolymers with moderate number-average molecular weights in high yields.For the copolymers from the achiral monomers with appropriate bulky pendent groups,the moderate steric hindrance between the pendent groups enabled the copolymer main chains to adopt helices preferring the same handed screw sense taken by the chiral units;the corresponding copolymers exhibited higher CD signal intensity even when compared with the pure chiral polymer.However,for the achiral co-monomers with too small or too large pendent groups,they were unfavorable for the resulting copolymers to prefer the helical handedness adopted by the chiral units,leading to low CD signal intensity.These findings would be helpful for us to design and synthesize novel helical N-propargylamide poly- and copolymers with high optical activity.
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发布时间：2021-03-19 - 摘要：A set of microlayer coextrusion system was designed to prepare 2-layer,16-layer,32-layer and 64-layer composites.The blended materials were also prepared by conventional blending technology to study the effects of phase morphologies on properties of blends.The SEM micrographs showed that the multiplying elements acted as the function of delamination and multiplication.For investigating the mechanical properties of stratified and blended samples,an equivalent box model was introduced,and a series of corresponding tensile tests were performed.Both the theoretical and experimental results showed that with the same volume fraction of POE (VPOE),the stratified composites,especially multilayer samples,had higher yield strength and a comparable elongation at break comparing with those of the blends.According to stress-strain curves,it was illustrated that the yield phenomena behaved more evidently for 64-layer samples than for blends,which almost had no yield peak,when VPOE approached to 50%.By studying the effect of layer numbers on tensile properties,it was found that when VPOE was not too great,the yield strength was even larger than theoretical values acquired by an additive principle.Those distinct characteristics of multilayer materials in the aspect of mechanical properties might provide a novel approach to produce high-performance composites.
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发布时间：2021-03-19 - 摘要：Soluble,thermally stable phthalazinone-containing poly(ether nitrile ketone ketone)s (PPENKK) have been synthesized by the nucleophilic displacement reaction of five kinds of phthalazinone_containing monomers with 2,6-dichlorobenzonitrile (DCBN) and bis-1,4-(4-fluorobenzoyl)benzene (BFBB).The polymerization reactions were conducted in sulfolane in the presence of K2CO3 to give high molecular weight polymers with intrinsic viscosities of 0.51～1.15 dL\5g-1.The structure of polymers obtained was characterized by FT-IR.The polymers showed amorphous nature as determined by wide angle X-ray diffraction (WAXD) and were readily soluble in a variety of polar sovents at room temperature,such as N-methyl-2-pyrrolidone (NMP),N,N-dimethylacetamide (DMAc),N,N-dimethylformamide (DMF),chloroform,and so on,and could be easily cast into flexible and transparent films,which could be ascribed to the kink non-coplanar structure and ether linkages in the main chain.Moreover,the polymers exhibited outstanding thermal properties.The glass transition temperatures were from 252℃ to 294℃,and the temperatures for 10% weight loss in nitrogen were above 457℃.
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发布时间：2021-03-19 - 摘要：Amine-containing acrylate latex has been widely used in fabricating water-borne adhesives and coatings because of its good desirable performances.Such latex is also a fundamental component for making ambient self-curable latex compositions.During emulsion copolymerization amine-containing monomer can polymerize in water phase due to its high water solubility,and the polymer generated dissolves in water phase.This phenomenon is believed to have strong effect on the stability of latex colloids during polymerization stage and shelf stage.N,N-Dimethylaminoethyl methacrylate (DMAEMA) is a typical tertiary amino monomer employed in preparation of amine-containing latex.Its homopolymer (PDMAEMA) is water soluble and sensitive to temperature and pH.In the present study,phase transition behavior and colloid formation of PDMAEMA (Mw=8.56×104) in aqueous solution were investigated by dynamic light scattering at different temperatures,pHs and ionic strength.The effect of emulsifier on the thermo-induced phase transition of PDMAEMA was also studied.It was found that: (1) 1％ PDMAEMA aqueous solution showed no phase transition on heating at pH<8.2.The lower critical solution temperature (LCST) of the solution decreased sharply from 67℃ to 42.5℃ as pH increased from 8.2 to 9,and decreased slowly to 40℃ when pH was further increased to 11; (2) A higher ionic strength (NaCl concentration) in the solution resulted in a lower LCST; (3) The presence of emulsifier,sodium dodecyl sulfate at the concentration of 1.92%,in PDMAEMA aqueous solution (pH 8.8) could keep the polymer soluble even on heating at 70℃ (no phase transition occurred).Moreover,the relationship between the formation of homo-PDMAEMA or DMAEMA-rich copolymer in aqueous phase during emulsion polymerization and the stability of the latex were also investigated.The results obtained suggest that the stability of DMAEMA-containing polymer latex can be improved by selecting a proper emulsifier,designing optimized formulation and polymerization conditions.
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发布时间：2021-03-19 - 摘要：A series of blends of poly(2,5-benzoxazole) (PABPBO) with poly(2,5-thienylbenzobisthiazole) (PPBZTT) and their random copolymers P(ABPBO-co-PBZTT) with different PBZTT content were prepared.The effect of structure variation on optical properties of copolymers and blends were investigated in detail using UV absorption and emission spectroscopy.Copolymers both in dilute solution and in film exhibited efficient intra- and/or inter-molecule energy transfer,and the quantum efficiencies of copolymers were enhanced obviously compared to pure PPBZTT polymer.Maximum emission wavelength of copolymers red shift with increasing PBZTT content was also observed.Though energy transfer was also found in blends,the quantum efficiencies of blends were similar to that of pure PPBZTT polymer because aggregates were easily formed in blends.
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发布时间：2021-03-19 - 摘要：Poly(N,N-dimethylacrylamide-co-N-isopylacrylamide) ［P(DMAA-co-NIPAm)］ hydrogels have been prepared by photopolymerization technique in the solvent of H2O at different temperatures (50℃ and 28℃) respectively,and N,N′-methylene bisacrylamide (Bis) was used as the cross-linking agent.The Comparing performances of the hydrogels (P2) synthesized at 50℃with that (P1) at 28℃ by the photo-induced polymerization have been investigated in cluding the network structure,swelling and shrinking behavior,temperature-sensitive behavior and so on.The results show that the hydrogels (P2) synthesized at 50℃exhibit a structure different from that of hydrogels (P1) and exhibit fast responsive properties and more excellent water release behavior (shrinking behavior) at high temperature.The reasons causing the property improvement of the hydrogels were discussed.The products were characterized by Fourier transform infrared(FTIR) spectroscopy and scanning electron microscopy(SEM).Swelling dynamics,water release behavior and temperature-sensitive performances of the hydrogels were discussed.The synthetic procedure of the photo-induced copolymerization was quickly finished within two minutes.
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发布时间：2021-03-19 - 摘要：4-Benzophenone methoxyl methacrylate (BPMM) and 3,4-methylenedioxybenzene methoxyl methacrylate (MDBMM) were synthesized and the photoinitiating effect of BPMM/MDBMM combinations was evaluated as well.Real time infrared spectroscopy (RTIR) with a horizontal sample holder was used to record the polymerization kinetics of UDMA/TEGDMA (70/30 W/W) initiated by BPMM/MDBMM.Dynamic mechanical analyzer (DMA) was used to study the mechanical properties of the cured samples.The results showed that,with increasing of the amount of MDBMM,the rate of polymerization (Rp) and final double bond conversion (Pf) increased.However,with the increase of BPMM concentrations,an optimum BPMM concentration occurred (0.8%).Comparison with the conventional BP/EDMAB initiator system under the same curing conditions indicates that BPMM/MDBMM shows a lower initiating reactivity,but a comparable Pf,Tg and the storage modulus around 37℃ of the products.Moreover,as a derivative of natural component from black peppers MDBMM is more promising in biomedical applications.
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发布时间：2021-03-19 - 摘要：A small molecule core (TMP-SK3)with three terminal carboxyl groups was synthesized successfully by the reaction of 1,1,1-trihydroxymethylpropane with the excessive sebacic acid diacetic anhydride.Then,the core molecule was used as a coupling agent to condensate with polyethylene glycols (PEG)of different molecular weight or polyethylene glycol monomethyl ether (PEGm)in the presence of stannous octoate as catalyst and diphenyl ether as azeotropic agent to remove water.Thus,the three-arm star-shaped polyethylene glycol was obtained successfully,and was characterized by 1H-NMR,DSC,GPC and XRD,etc.DSC measurements indicate that the crystallizing temperature and the melting temperature of the three-arm star-shaped polyethylene glycol were different from those of the corresponding linear PEG because the existing of TMP-SK3 altered its crystallizing velocity and the perfect degree of crystals.
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发布时间：2021-03-19 - 摘要：A series of sulfonated SPEEKKS copolymers with different DS were synthesized by aromatic nucleophilic polycondensation of disodium 3,3′-disulfonate-4,4′-dichloro-diphenylsulfone(SDCDPS),tertbutylhydroquione(TBHQ)and 1,4-bi(4′-fluorobenzoyl)benzene.Synthesized sulfonated copolymers were characterized by FTIR,TGA and DSC.Moreover,the microstructure of membranes was investigated by TEM,and the relationship between structure and performance was established.Physical and electrochemical performances of all membranes were studied thoroughly.The results showed that the proton conductivity of SPEEKKS-4 membrane reached 0.061 S/cm,which was close to that of Nafion 117 at 80℃.However,the methanol diffusion of SPEEKKS-4 membranes only reached 3.4×10-7 cm2/s and was much lower than that of Nafion 117. The new membrane displayed good potential in application as proton exchange membranes (PEM) in PEMFC and DMFC.
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发布时间：2021-03-19 - 摘要：2,5-Di(4′-formylphenyl)styrene was synthesized via Suzuki cross-coupling reaction of 2,5-dibromostyrene and p-formylphenylboronic acid.In the presence of catalytic amount of glacial acetic acid,a pair of chiral nonracemic vinyl monomers,(+)-2,5-di {4′-［(N-(S)-α-methylbenzylimine)methylene］phenyl}styrene (M 1)and(-)-2,5-di {4′-［(N-(R)-α-methylbenzylimine)methylene］phenyl}styrene (M 2),was synthesized through the condensation reaction between 2,5-di(4′-formylphenyl)styrene and optically pure α-methylbenzylamine.Optically active polymers were prepared via free radical polymerization of M 1 and M 2 initiated by AIBN or BPO depending on polymerization temperature.The results from specific optical rotation,UV-Vis absorption spectra and circular dichroism spectra indicated that the polymer obtained might adopt a helical conformation with a predominance of one helical screw sense.The polymerization condition had pronounced effects on the chiroptical properties of the polymers.Polymer with larger helical chirality was obtained when the polymerization was carried out in more polar aromatic media at higher temperature.Due to the steric hindrance of the bulky p-terphenyl groups,the main chain helical chirality formed during polymerization was thermally stable and displayed memory effect.
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发布时间：2021-03-19 - 摘要：Two novel poly(p-phenyleneethynylene)(PPE) samples with liquid crystal (LC)groups were synthesized,and their liquid crystal properties and photoluminescent properties were investigated.It was found that the LC properties of these polymers were deeply affected by the density of the side-chain LC groups,and the polymer with high content of LC groups exhibited the obvious smectic mesophase as illustrated by differential scanning calorimetry and polarized optical microscopy.The photoluminescence spectra showed that there was a remarkable change for the LC polymer in the solid film state before and after annealing,likely attributed to the morphological change by thermal annealing.Additionally,Fòrst energy transfer in the concentrated solution was also reported.Moreover,atom force microscope (AFM) images were investigated with the temperature changing.As a result,we concluded that spectra can be altered by the conjugated polymer morphologies with different LC states,and this provided us a promising aspect for the future preparation of controlled light emitting polymers.
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发布时间：2021-03-19 - 摘要：The influences of activation temperature on the structure and properties of aqueous polyurethane (APU) films were studied by means of FTIR,DSC and SEM.The testing results showed that when the film of APU is treated at a higher temperature,the chain segment motion can take place easily which leads to the rearrangement of the molecular chains.Furthermore,disordered hydrogen-bond intensity of APU films increased obviously and ordered hydrogen-bond intensity increased lightly during this process,which leads to non-perfect long-range ordered structure and a little perfection.The ordered structure in APU films formed effective physical cross-link point,which is conducive to better physical properties of APU films.
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发布时间：2021-03-19
Research Article
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