最新刊期
卷 ， 期 7 ， 2010
- 摘要：The carboxylic fluorocarbon polymer poly(hexafluorobutyl acrylate-co-methacrylic acid)(P(HFBA-co-MAA)) and poly(dodecafluoroheptyl methacrylate-co-methacrylic acid)(P(DFHMA-co-MAA)) were prepared by solution polymerization.The electrospinning experiments showed that when the amount of MMA in copolymers decreased the spinnability of P(DFHMA-co-MAA) and P(HFBA-co-MAA) copolymers became worse,at the same time the concentration of two coplymers solution decreased,and the polarity and boiling point of solvent gradually reduced; the diameter of fibers enlarged with increasing the amount of butanone in the spinning solvent; the spinnability of P(DFHMA-co-MAA) was better than that of P(HFBA-co-MAA).Using P(DFHMA-co-MAA) fibers as carrier,photocatalyst ZnS were prepared on the surface of fibers by a two-step method.The XPS results showed that Zn2+ were introduced onto the surface of fibers by coordinating with the carboxyl of fluoropolymer first,then coordinated Zn2+ reacted with S2- provided by thioacetamide to form ZnS.The amount and particle size of ZnS increased with increasing the proportion of MAA in the copolymer.Nano dimension ZnS particles could be obtained when the proportion of MAA in the copolymer was 10 wt%.The photodegradation and FTIR analysis showed that the as prepared ZnS/P(DFHMA-co-MAA) fiber composites had good stability under UV irradiation.
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发布时间：2021-03-19 - 摘要：Sodium montmorillonite (Na-MMT) was modified with 1-carboxymethyl-3-methylimidazolium chloride (CMMIm),then aniline monomers were inserted into CMMIm/MMT.Using ammonium persulfate and hydrochloric acid as oxidant and dopant,respectively,conductive polyaniline/ionic liquid/montmorillonite(PANI/CMMIm/MMT) nanocomposites were prepared by chemical oxidative polymerization of aniline(An) which was intercalated in the interlayer of MMT.PANI/CMMIm/MMT nanocomposites were characterized with the measurements of FTIR,XRD and TG.The experimental results indicated that the conductivity of PANI/CMMIm/MMT nanocomposites was 0.3 S/cm when the amount of CMMIm/MMT was 7.5%,the concentration of HCl was 1 mol/L,the mass ratio of PANI and (NH4)2S2O8 was 1∶1,the polymerization time and temperature were 6 h and 0℃,respectively.The conductivity of PANI/CMMIm/MMT nanocomposites was 2.5 times as high as that of PANI/Na-MMT and 7.5 times as high as that of PANI.The conducting stability of PANI/CMMIm/MMT nanocomposites is higher than that of PAn because the carboxyl of 1-carboxymethyl-3-methyl imidazolium chloride provided partial proton acid.
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发布时间：2021-03-19 -
EFFECT OF MULTIFUNCTIONAL MONOMER ON RHEOLOGICAL BEHAVIOR FOR MALEIC ANHYDRIDE GRAFTED POLYPROPYLENE
摘要：The effect of multifunctional monomer triallyl trimellitate (TATM) on the melt flow rate (MFR) and rheological behavior of maleic anhydride grafted polypropylene (maleated PP) was studied.TATM is not effective for stabilizing the MFR of maleated PP based on PP powder not containing antioxidant.However,TATM can effectively stabilize the MFR of maleated PP when PP powder was first melt compounded with antioxidant and then used as grafting raw material.The rheological results showed that the grafted PP based on PP pellets containing antioxidant had higher melt elasticity,indicating some grafted or crosslinked structure.The remarkable differences of the rheological results between maleated PP based on polypropylene powder and polypropylene pellets are discussed through the mechanism of free radical grafting reactions.The effect of TATM on stabilizing MFR is due to its effect on increasing the melt elasticity,which can offset the inevitable reduction of shear viscosity caused by β scission reaction of PP molecules during melt grafting.The differences of antioxidant content in PP powder and PP pellets can strongly influence the PP degradation during melt processing,therefore TATM shows different effects in different PP systems.- 19
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发布时间：2021-03-19 - 摘要：CuBr/N,N,N′,N″,N″-pentamethyldiethylenetriamine-catalyzed self-condensing atom transfer radical polymerization (SCATRP) of N-［4-(α-bromoisobutyryloxy)phenyl］ maleimide (BiBPM) with a large excess of (N,N-dimethylamino)ethyl methacrylate (DMAEMA) was carried out,in which the conversion,relative molecular weight (MW) and its distribution,absolute MW and specific viscosity of the PDMAEMA were monitored by gas chromatography,gel-permeation chromatography coupled with multi-angle laser light scattering and online visometry.The results showed that with the increase of the monomer conversion,the MW and polydispersity of the PDMAEMA increases gradually.The specific viscosity of the so-obtained PDMAEMA in tetrahydrofuran (THF) was significantly lower than that of the linear analogues with comparable MW,indicating the presence of the branched structure.The contraction factor (g′),as a function of the MW of the branched PDMAEMA,decreases with increasing MW,suggesting that the degree of branching (OB) decreased slowly.The above results suggested that the SCATRP with a large comonomer/inimer feed ratio is a multi-step process: the inimer-initiated ATRP of comonomers forms the primary chains of several repeating units and the SCATRP of the primary chains forms low-MW and high-degree of branching PDMAEMA during the early stage,and the ATRP of DMAEMA initiated by branched PDMAEMA during the later period,gives rise to the high-MW and low-degree of branching PDMAEMA.
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发布时间：2021-03-19 - 摘要：In order to meet the requirement of proton exchange membranes in direct methanol fuel cells (DMFCs),sulfonated poly(aryle ether ketone sulfone)/polypyrrole (SPAEKS/PPy) composite membranes with different contents of PPy were prepared in chemical in situ polymerization by means of ion-dipole interaction between the sulfonate groups of SPAEKS and imino groups of polypyrrole.The incorporation of polypyrrole particles into the clusters, which was the transport pathway,could change the morphology of the SPAEKS matrix.FTIR spectra suggested that the sulfonic acid groups on the copolymer backbone strongly interacted with amonium groups of PPy.SEM pictures showed that the PPy particles were uniformly distributed not only in regions near the surface but also in the internal space of the SPAEKS membranes matrix.The composite membranes showed good thermal stability,low water uptake,low swelling ratio both at length and thickness and relatively high proton conductive capability.The methanol diffusion coefficient (1.18×10-7 cm2/s) of SPAEKS/PPy-3 composite membranes is much lower than that of pure SPAEKS membranes (8.52×10-7cm2/s).At the same time,the selectivity increased with increasing the molar ratio between PPy and the sulfonate groups,meaning that the composite membranes have more impact on the reduction of methanol diffusion coefficient than that on proton conductivity.The selectivity of SPAEKS/PPy-3 composite membranes is much higher than that of pure SPAEKS membranes and other composite membranes,which suggests that the composite membranes with 0.99 molar ratio between PPy and the sulfonate groups of SPAEKS are promising as proton exchange membranes for DMFC applications.
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发布时间：2021-03-19 - 摘要：A proton exchange membrane (PEM) was produced by simultaneous radiation grafting of p-styryltrimethoxysilane (StSi) into polytetrafluoroethylene (PTFE) membranes,followed by sulfonation,hydrolyzation and condensation.The effects of solvent,absorbed dose,absorbed dose rate and monomer concentration on the degree of grafting (DOG) were studied.Toluene was chosen for its higher boiling point and giving a higher DOG with acceptable mechanical strength.DOG increased with increasing the absorbed dose and monomer concentration and changed little with the absorbed dose rate at 10~43 Gy . min-1.Monomer concentration of 3 mol . L-1 was better for reducing the copolymer.The degree of sulfonation (DOS) was as high as 92%~97% at DOG 23%,making the properties of the PEM rely much on the DOG.Scanning electron microscopy (SEM) gave imagines of radiation grafting happened through the surface to the centre of the membrane.The ion exchange capacity(IEC),water uptake,dimension expansion and proton conductivity grew up with the increase of DOG for more hydrophilic —SO3H,—Si—O—Si— crosslinking structure,and Si—OH groups were incorporated in the PEM.In addition,proton conductivity got better with temperature increase due to the good water uptake.Most of the grafted membranes exhibited lower methanol permeability than Nafion.The prepared PEM in this work showed a good combination of high IEC (1.53 mmol . g-1),dimension stability (dimension changed less than Nafion117 at 90℃),acceptable water uptake (63% at 90℃) and proton conductivity (1.5×10-2 S . cm-1 at 90℃ and DOG 72.5%),and low methanol permeability (0.82×10-6cm2 . s-1 at DOG 50.1%).
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发布时间：2021-03-19 - 摘要：The effect of phase morphology on mechanical properties of the immiscible blends of PA1010/PP have been studied via dynamic packing injection molding (DPIM).The tensile strength,tensile modulus and notched impact strength were found largely increased by means of shear.When the content of PP was 20%,the izod impact strength of dynamic samples was 21.3 kJ/m2,which was more than 3 times that for the static samples.The tensile strength of dynamic samples was 50.9 MPa when the content of PP was 20%,which was 1.5 times that for the static samples.SEM results showed that the shear-induced morphology with core in the center and shearing layer surrounding the core was observed in the cross-section areas of the specimens.SEM results also indicated a remakably decrease of domain size and more uniform dispersion of the dynamic molded specimens,especially when the content of PP was 20%,the domain size decreased from about 3.9 μm to about 1.4 μm.The observed higher mechanical properties in dynamic samples could be due to the effect of phase morphology under shear stress.The tensile strength of dynamic samples is higher than that of static samples in the whole composition region due to the molecular orientation induced by shear stress in DPIM,and the toughing mechanism lies in shearing-induced smaller domain size and the molecular orientation induced by shear stress in DPIM.
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发布时间：2021-03-19 - 摘要：To study the effect of adamantyl groups on the properties of temperature-sensitive hydrogels,hydrophobic monomer adamantyl methacrylate（AdMA）was synthesized and copolymerized with N-isopropylacrylamide (NIPAM).A series of temperature-sensitive P(NIPAM-co-AdMA) hydrogels with different content of AdMA were prepared.Fourier transform infrared (FTIR) spectroscopy was used to confirm the chemical structure of the resultant hydrogels.The peak of CO around 1714 cm-1 in FTIR spectra demonstrated that the AdMA units were successfully incorporated into the hydrogel network.The inner morphology of copolymer hydrogels was observed using an enviromental scanning electron microscope (ESEM).It is found that the morphology strongly depends on AdMA content.In a proper range(AdMA∶NIPAM≤3％),with the increase of AdMA content,the copolymer hydrogels can form perfect porous structure,but when the AdMA content increases further,the porosity decreases,even the hydrogel surface becomes compact.The volume phase transition temperature (LCST) was characterized by differential scanning calorimetry (DSC).The results indicate that the LCSTs of the copolymer hydrogels decrease linearly with the increase of AdMA component,so it can be designed easily to obtain hydrogels with needed LCST.The equilibrium swelling ratios(SR) and the deswelling kinetics of the hydrogels were also measured gravimetrically.It is noteworthy that the swelling properties of the copolymer hydrogels can be optimized by the proportion of AdMA,with optimum AdMA content,the SR of the copolymer hydrogel can exhibt fast change with temperature,and the deswelling rate increase significantly.The hydrogel with 3% AdMA （AdMA∶NIPAM＝3％）can lose 92％ of water within 5 min and reach deswelling equilibrium within 10 min with a water retention below 4%.
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发布时间：2021-03-19 - 摘要：Four random poly(ether ether ketone ketone) copolymers (PEEKK-X/PEEKK-A)s were prepared via nucleophilic aromatic substitution polycondensation of 9,9-bis(4-hydroxyphenyl)xanthene (BHPX),1,4-bis(4-fluorobenzoyl)benzene and bisphenol A(BPA).The PEEKK-X/PEEKK-A copolymers were characterized by FTIR,DSC,TGA and WAXD,etc. The results showed that the copolymers having number-average molecular weights (Mn’s) in the range of 39500~41600,the polydispersity index ranging from 1.95 to 2.05 were all amorphous and readily soluble in common organic solvents such as N-methyl-pyrrolidone(NMP),N,N-dimethylacetamide(DMAc),THF and CHCl3 at room temperature.These polymers showed relatively high glass transition temperatures in the range of 185~218℃,almost no weight loss up to 430℃ in nitrogen or air atmosphere,decomposition temperatures at 5% weight loss ranging from 490℃ to 511℃,and 480℃ to 505℃ in nitrogen and air,respectively,and char yields at 700℃ in nitrogen higher than 40%.Transparent,flexible and tough films of these polymers cast from their solutions exhibited tensile strengths ranging from 58 MPa to 75 MPa,Young’s moduli from 1.95 GPa to 2.70 GPa,and elongations at break from 8% to 13%.The novel PEEKK-X/PEEKK-A copolymers derived from the bisphenol monomers of BHPX and BPA with molar ratio in the range of 60/40 to 50/50 might serve as new candidates for processable high-performance polymeric materials with potential applications in high technology fields.
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发布时间：2021-03-19 - 摘要：Polymer dispersed liquid crystal (PDLC) films were prepared by photopolymerization induced phase separation (PIPS) with living macromolecule,synthesized by RAFT and iniferter in sequential steps.The living macromolecule with multi-iniferter was called RAFT-MI.The effects of RAFT-MI concentration on morphologies,transmittance,threshold voltage (Vth),saturated voltage (Vsat),contrast ratio and memory effect of PDLC were studied in detail.It was found that the liquid crystal droplet of PDLC increased at first and then decreased with the concentration of RAFT-MI varying from 10 wt% to 30 wt%,while Vth decreased from 3.1 V to 1.5 V and Vsat decreased from 16 V to 6.8 V.On-state transmittance increased with the concentration of RAFT-MI varying from 10 wt% to 15 wt%,and then decreased gradually due to the mismatch between the refractive index of liquid crystal and that of polymer matrix.In addition,contrast ratio increased from 2.2 to 4.0 at first and then decreased later; memory effect of PDLC was weakened.Therefore,the new combined method of living radical polymerization RAFT and Iniferter successfully improved the electro-optical properties of PDLC.
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发布时间：2021-03-19 - 摘要：The aim of this study was to study the effect of polyamidoamine(PAMAM) dendrimers on the aqueous solubility of ketoprofen and investigate the mechanism of solubilization.PAMAM dendrimers of G1.0,G1.5,G2.0,G2.5,G3.0 and G3.5 were used as drug carriers of ketoprofen. The effects of pH and concentration of the dendrimers on the solubility of ketoprofen were studied by UV spectroscopy.In addition,the computational simulation was used to investigate the mechanism of interaction between PAMAM dendrimers and ketoprofen.Results showed that the pH,generation size,and concentration influenced the solubilization of ketoprofen.The solubility of ketoprofen increased with the increase of pH ,generation size,and concentration of PAMAM dendrimers at pH 4.0～6.0.Both amino and ester terminated dendrimers caused the increase in ketoprofen solubility.However,at each pH,the solubility of ketoprofen was greater in the presence of amino-terminated dendrimers compared to the ester-terminated dendrimers possessing the same number of surface functional groups.The results of computational simulation show that interaction between ketoprofen and PAMAM dendrimers is mainly electrostatic force.Its mechanism of solubilization maybe an electrostatic interaction between the carboxyl group of ketoprofen and the primary amines or tertiary amines of PAMAM dendrimers.
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发布时间：2021-03-19 - 摘要：Konjac glucomannan acetate with high degree of substitution (KGM acetate)was synthesized by reaction of konjac glucomannan (KGM)and acetic anhydride catalyzed with concentrated sulphuric acid.The influences of the reaction conditions on the degree of substitution (DS)were investigated,and the optimum ratio of ethanol/water,reaction time,reaction temperature,concentration of catalyst and ratio of KGM/acetic anhydride were 5∶5,2 h,75℃,0.1 mol/L and 5∶40 (g/mL),respectively,under which the DS of product was as high as 2.93,and the molecular weight of KGM acetate was significantly lower than that of KGM.KGM and KGM acetate were characterized by means of FTIR,XRD,SEM,TGA,DSC and rotary rheometer.The results showed that the carbonyl (CO)characteristic absorption peak of KGM acetate was much higher than that of KGM.Most of the apparent morphology of KGM acetate was loose flocculent.KGM and its acetate both were amorphous structure.The thermal stability of KGM acetate was lower than that of KGM,and the decomposition temperature of KGM and KGM acetate was 261.1℃ and 204.6℃,respectively.Before undergoing thermal decomposition,KGM acetate showed a glass transition temperature (Tg)at about 128.49℃,but KGM did not.The shear viscosity was very sensitive to temperature,so that the processing flowability of KGM acetate can be regulated easily by changing temperature.
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发布时间：2021-03-19 - 摘要：To develop and characterize a new cancer target gene delivery carrier,which could be used as potential blood pool magnetic resonance (MR)contrast agents,a novel FAM-AGKGTPSLETTPC-COOH/poly(ether-amide)(FAM-13/PEG/DTPA)copolymer (Ⅲ)with fluorescence probe was designed and obtained first from the reaction of the amino group terminated poly(ether-amide)(PEG/DTPA)copolymer ligand (Ⅱ)with heterobifunctional cross-linker m-maleimidobenzoyl-N-hydroxysuccinimide ester(MBS)(Step 2)，and then Michael addition of CC double bond in MBS moiety with SH group in FAM-labeled hepatocarcinoma specific adhesin peptide,FAM-AGKGTPSLETTPC-(SH)-COOH（FAM-13）,in high yield(Step 3).Ⅱ was prepared by the reaction of diethylenetriamine pentaacetic acid dianhydrid(DTPAA)with amino group terminated PEG(Ⅰ)(Step 1).The two copolymers of Ⅱ and Ⅲ were characterized by 1H-NMR and 13C-NMR measurements.The liver tumor-specific identification and antigen localization of Ⅲ with the fluorescin-labeled FAM-13 peptide were performed under cellular level.Targeting properties of Ⅲ were tested on the normal cells and liver cancer cells,respectively.No fluorescence was observed on normal liver cells L-02,while strong yellowish green fluorescence was observed on the liver cancer cells BEL-7404.The property of FAM-13 peptide in Ⅲ for recognizing specifically the liver cancer cells was demonstrated.It was also demonstrated that the chemically synthesized Ⅲ with peptide FAM-13 still had the property for targeting on the surface membrane of liver cancer cells in vitro，thus further indicating that the specific targeting effect of the objective tissue was mediated by the peptides of Ⅲ insert into the cell membrane.It is evident that the Ⅲ with FAM-13 peptide would be an excellent candidate for the targeting therapy to hepatocarcinoma.So ligand molecules Ⅲ with targeting peptides can target hepatocellular carcinoma.Ligand Ⅲ is a promising candidate,which can be coordinated with Gd3+ ion to give the macromolecular contrast agent.To develop and characterize a new cancer target gene delivery carrier,which could be used as potential blood pool magnetic resonance (MR)contrast agents,a novel FAM-AGKGTPSLETTPC-COOH/poly(ether-amide)(FAM-13/PEG/DTPA)copolymer (Ⅲ)with fluorescence probe was designed and obtained first from the reaction of the amino group terminated poly(ether-amide)(PEG/DTPA)copolymer ligand (Ⅱ)with heterobifunctional cross-linker m-maleimidobenzoyl-N-hydroxysuccinimide ester(MBS)(Step 2)，and then Michael addition of CC double bond in MBS moiety with SH group in FAM-labeled hepatocarcinoma specific adhesin peptide,FAM-AGKGTPSLETTPC-(SH)-COOH（FAM-13）,in high yield(Step 3).Ⅱ was prepared by the reaction of diethylenetriamine pentaacetic acid dianhydrid(DTPAA)with amino group terminated PEG(Ⅰ)(Step 1).The two copolymers of Ⅱ and Ⅲ were characterized by 1H-NMR and 13C-NMR measurements.The liver tumor-specific identification and antigen localization of Ⅲ with the fluorescin-labeled FAM-13 peptide were performed under cellular level.Targeting properties of Ⅲ were tested on the normal cells and liver cancer cells,respectively.No fluorescence was observed on normal liver cells L-02,while strong yellowish green fluorescence was observed on the liver cancer cells BEL-7404.The property of FAM-13 peptide in Ⅲ for recognizing specifically the liver cancer cells was demonstrated.It was also demonstrated that the chemically synthesized Ⅲ with peptide FAM-13 still had the property for targeting on the surface membrane of liver cancer cells in vitro，thus further indicating that the specific targeting effect of the objective tissue was mediated by the peptides of Ⅲ insert into the cell membrane.It is evident that the Ⅲ with FAM-13 peptide would be an excellent candidate for the targeting therapy to hepatocarcinoma.So ligand molecules Ⅲ with targeting peptides can target hepatocellular carcinoma.Ligand Ⅲ is a promising candidate,which can be coordinated with Gd3+ ion to give the macromolecular contrast agent.
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发布时间：2021-03-19 - 摘要：The bromized sodium dodecyl sulfate(SDS)-chitosan(CS)complex(Br-SCC)was synthesized by conjugating 2-bromo-2-methyl propionic acid to the hydroxyl groups of SCC which was used as an organo-soluble precursor in this study.Br-SCC was used as a macromolecular ATRP initiator to polymerize methyl ether poly(ethylene glycol)methacrylate(PMPEGMA)using copper(I)bromide/bipyridine as a catalyst,yielding SCC-O-PMPEGMA.SDS was removed from the product by precipitating SCC-O-PMPEGMA solution into aqueous tris(hydroxymethyl)amine (Tris) medium.The chemical structure of the intermediate and CS-O-PMPEGMA was studied by FTIR and 1H-NMR.The substitution degree of bromobutyric acid could be modulated by bromobutyric acid/SCC feed ratio.The degree of polymerization of PMPEGMA could be controlled by varying the PMPEGMA/Br-SCC ratio.Complexation behaviors between CS-O-PMPEGMA and heparin were studied by dynamic light scattering,zeta potential analyzer and TEM.With the increase of heparin/CS molar ratio (X),there was an increase in the nanoparticle size and decrease in the zeta potential of the particles.When X was above 2,the size and the zeta potential reached a plateau stage.The ultimate size of the spherical nanoparticles was about 44 nm and the zeta potential was -8.9 mV.CS-O-PMPEGMA which could be conveniently synthesized according to the scheme proposed in this study has well-defined chemical structure.The grafting of PMPEGMA has no effect on the cationic density of the final product.In addition,the copolymers could form spherical micelles with anionic agents.The above characteristics of CS-O-PMPEGMA make it promising for tumor targeting and gene delivery.
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发布时间：2021-03-19 - 摘要：The polyamidoamine (PAMAM)dendrimers having different generations (G2 and G4)modified by β-cyclodextrin (β-CD),PAMAM(G2,G4)-β-CD,were synthesized using substitution reaction from mono-6-iodine-β-cyclodextrin and PAMAM dendrimers，and the molecular structures were characterized by 1H-NMR and IR.The molecular interaction between various dendrimers and levofloxacin lactate (LFL)was determined by fluorimetry in buffer solution (pH=7.4)at 25℃.It was found that the PAMAM(G2,G4)-β-CD possesses higher sensitizing ability than that of the corresponding parent dendrimers and natural β-CD,and it increases concomitantly with the increases of generation and content of β-CD,suggesting that the PAMAM(G2,G4)-β-CD possesses strong inclusion ability with LFL.The possible interaction mechanism between PAMAM-CD and LFL was proposed by 1H-NMR analysis and theoretical calculation.The results showed that the LFL molecule was placed in the amino end of dendrimer molecule and between the sides of cyclodextrin cavities to form supramolecular complexes.Furthermore,the results indicate that the main driving force of the system could be attributed to the electrostatic interaction as well as hydrogen bonding between the LFL and PAMAM-CD,and fully reflects the synergistic effect of intermolecular forces.
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发布时间：2021-03-19 - 摘要：Porous high oil-absorption resin was successfully prepared via bicontinuous microemulsion polymerization. The main aims of this paper are trying to control the pore structure of the polymer. The emulsifier system, including an anionic surfactant sodium dodecyl sulfate (SDS), an anionic-nonionic mixture of sodium dodecyl sulfate (SDS) and Tween 80(T80), could be used to prepare stable, transparent microemulsion. The microemulsion phase diagrams of the system consisting of surfactants, H2O/EtOH and MMA/BA are shown. The resulting polymers were studied by SEM. The oil-absorption property of the resin was determined. The effects of emulsion system, the content of aqueous phase, ratio of monomers, the content of crosslinker and initiator on oil absorption capacity of the prepared resin were disussed. The SEM results indicated the formation of a bicontinuous structure in the high oil-absorption resin at mixture aqueous concentrations between 30 wt% and 50 wt%. The pore size or the width of the polymerized bicontinuous microemulsions increased substantially with the increase of the aqueous content (30 wt%～50 wt%) in precursor microemulsions. This total polymerization approach enables one to synthesize various bicontinuous nanostructures polymeric materials by simply adjusting the concentrations of aqueous in precursor bicontinuous microemulsions. The results indicated that the porous high oil-absorption resin could reach oil balance in two minutes with aqueous content 50 wt%. The oil-absorption in benzene, tetrahydrofuran, carbon tetrachloride can reach 15.5 g/g，15.5 g/g，31.7 g/g to the most, respectively.
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发布时间：2021-03-19 - 摘要：The role of non-native hydrogen bonding on the kinetic process of helix formation for a homopolypeptide chain was explored based on a coarse-grained lattice model and dynamic Monte Carlo simulation.It was found that,though postponing the thermodynamic helix-coil transition,non-native hydrogen bonding can decrease the energy barrier of the folding kinetic process,and further increased the folding rate below a specific temperature.The distribution of folding trajectories indicated that the slow folding trajectories were reduced with the inclusion of non-native interactions,which can evidently influence the folding time.On the other hand,the evolution of chain conformation and the length of helix segment were investigated,and the non-native hydrogen bonding was found to delay the formation of native hydrogen bond and weaken the stabilization of the corresponding native conformation,thus speeding up its unfolding process.Our research indicated that the occurrence of non-native interaction can offer a potential means for frequently dynamical adjusting of protein conformation so as to perform biological functions.
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发布时间：2021-03-19 - 摘要：Polysulfone (PSF) was chloromethylated using 1,4-bis(chloromethoxy)butane (BCMB) without carcinogenitic toxicity as chloromethylation reagent,resulting in chloromethylated polysulfone (CMPSF).The chemical structure of CMPSF was characterized by FTIR,1H-NMR and chemical analysis method.The effects of main factors on the chloromethylation reaction of PSF were examined.By using three tertiary amines,triethylamine (TEA),tripropylamine (TPA) and tri-n-butylamine (TBA),the quaternization reaction of CMPSF was carried out,respectively,and then the crosslinking reaction was performed with 4,4′-bipyridine as crosslinker,obtaining polysulfone anion-exchange membrane (PSFAEM).The main properties of PSFAEM were determined including ion-exchange capacity (IEC),water content (WC) and membrane resistance (Rm).The experimental results show that the chloromethylation reaction of PSF with BCMB can be carried out favorably,and CMPSF with a chloromethylation degree of 1.75 mmol/g can be obtained as with chloroform as solvent and SnCl4 as Lewis catalyst.The properties of PSFAEM such as IEC,WC and Rm are closely related with quaternization time and the structure of the tertiary amine.In the same quaternization time,the anion-exchange membrane PSFAEM prepared with TEA,in whose molecule the number of carbon atom in alkyl group on N atom is small,has relatively high IEC,WC and lower Rm.As using the same tertiary amine,the IEC and WC of PSFAEM are increased with increasing the quaternization time,and Rm decreases.
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发布时间：2021-03-19 - 摘要：Poly(p-phenylene terephthalamide) fibers were treated in the range of 250~400℃ under free-end in air.Their mechanical properties and structure parameters were characterized by mechanical testing,Fourier transfer infrared spectroscopy,wide angle X-ray diffraction,sonic velocimetry and viscocimetry.It was found that the tenacity of aged samples decreased rapidly at the early stage of ageing due to the disorientation of molecular chains.Then,thermal degradation made the tenacity to keep on decreasing with time,which was consistent with the second-order kinetics equation with apparent activation energy of 32.4 kJ/mol.With the increase of ageing temperature,an obvious decrease in tenacity was found.However,the tenacity decreasing rate slowed down above 350℃,which could be related to the occurrence of slight cross-linking,the increasing of crystallinity and the perfection of the crystallites.The modulus of aged sample was lower than that of untreated sample,since the disorientation of molecular chains in amorphous region was dominant below 350℃.The modulus of aged sample increased above 350℃ because of more perfect crystallization structure,which was indicated by the smaller distortion of second kind lattice,gII,and larger value of a,b axis due to the combination of adjacent crystallites.
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发布时间：2021-03-19
Research Article
- 摘要：Hyperbranched polystyrene synthesized by the copolymerization of styrene and p-chloromethyl styrene was used as initiator to initiate the ATRP reactions of styrene and methyl methacrylate with CuCl/ pentamethyldiethylenetriamine as catalysts.The reaction dynamics were studied.It was found that the ATRP the reaction gelatinized easily in good solvent chlorobenzene.The monomer conversions before gelation were small.If poor solvent 1,4-dioxane was added in chlorobenzene before gelation,the gelatinization reactions could be eliminated efficiently.The monomer conversions could reach to high values and muti-arm star polymers with high molecular weight about a million were synthesized.This is new method to prepare multi-arm star polymers with high molecular weight.
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发布时间：2021-03-19 - 摘要：The monomer 1,4-diiodo-2,5-di(propyloxysulfonate)benzene and 2,6-diethynylpyridine were synthesized and a meta-linked anionic poly(pyridinylene ethynylene) conjugated polyelectrolyte m-PPYPE-SO3Na was synthesized via Pd-catalyzed Heck-Sonogashira coupling reaction.Monomers and the polymer were characterized by Fourier transformed infrared spectroscopy and proton nuclear magnetic resonance spectroscopy.The conjugated polyelectrolyte m-PPYPE-SO3Na was characterized by UV-Vis and photoluminescence spectroscopy and the solution photophysics properties of the polymer were investigated.The fluorescence spectra of the conjugated polyelectrolyte in different solvent and under different polymer concentrations showed concentration- and solvent-dependency of the conjugated polyelectrolyte,respectively,which could be attributed to the aggregation of the conjugated polyelectrolyte in water solution.The emission peak of the aggregation disappeared approximately when the concentration of the polymer was about 1×10-6 mol/L,and this fact shows that the extent of the polymer aggregation was very low.It was found that surfactant affected the aggregation of the polyelectrolyte.The introduction of polymer-type surfactant poly(vinyl pyrrolidone) (PVP) into the water solution of m-PPYPE-SO3Na increased the fluorescence intensity of the polymer solution.The interaction of PVP with m-PPYPE-SO3Na in aqueous solution broke the aggregation of the conjugated polyelectrolyte.The solution photophysics properties suggests that the conjugated polyelectrolyte has potential to be a kind of water soluble fluorescence probe.
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发布时间：2021-03-19 - 摘要：Two kinds of epoxy-based azo polymers containing thiazoleazobenzene chromophores have been designed.An epoxy-based precursor polymer was prepared by polymerization of diglycidyl ether of bisphenol-A and aniline.Two 2-aminothiazole derivatives,such as 2-amino-4-chloro-5-formylthiazole and 2-amino-4-chloro-5-dicyanovinylthiazole, were synthesized and their diazonium salts were prepared.The precursor polymer was postfunctionalized through azo-coupling reactions to form two azo polymers BP-1A-T-F and BP-1A-T-2CN.The azo polymers were characterized by the spectroscopic methods and thermal analysis.Polymers containing heteroaromatic chromophores exhibit improved temporal stability and show good solubility and processibility.The λmaxs of BP-1A-T-F and BP-1A-T-2CN obtained by UV-Vis spectroscopy are 579 nm and 650 nm; Tgs of the polymers are 152℃ and 149℃,respectively.
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发布时间：2021-03-19 -
SYNTHESIS AND CHARACTERIZATION OF Zr CATALYST WITH PHENOL NITRONE LIGAND FOR ETHYLENE POLYMERIZATION
摘要：A new non-metallocene early transition metal catalyst with phenol nitrone ligand for ethylene polymerization was designed and successfully synthesized by the reaction of phenol nitrone ligand with zirconium tetrachloride.Phenol nitrone ligand was obtained by the reaction of phenolic aldehyde with hydroxylamine.The structure of the catalyst and the phenol nitrone ligand were characterized by infrared spectrum (IR),nuclear magnetic resonance (1H-NMR),elemental analysis and mass spectrometry (MS).The catalytic behavior of the catalyst for the ethylene homopolymerization has been investigated with methyl aluminoxane （MAO）as cocatalyst.The catalyst exhibits a high ethylene homopolymerization activity (＞106g/（molZr . h）) and good thermal stability.The catalytic activity of the catalyst increases with the increment of the temperature and keeps at 105 g/（molZr. h） even under 100℃.Besides,the molecular weight and the molecular weight distribution of the polyethylene were characterized by gel permeation chromatography (GPC).The molecular weight of the resulting polymers reaches 105,and the molecular weight distribution (Mw/Mn) is around 2.The thermal properties of the obtained polymers were also investigated with differential scanning calorimetry (DSC),the Tm of the polymer was around 132℃.Based on the above results,it can be concluded that the early transition metal catalyst with phenol nitrone ligand synthesized in this report is a single active site homogeneous catalyst with good thermal stability and high catalytic activity in ethylene polymerization.- 26
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发布时间：2021-03-19 - 摘要：Novel electroactive and biodegradable graft copolymers with aniline tetramer side chains were synthesized by conversing the side carboxyl groups of poly(L-glutamic acid) to active N-oxysuccinimide ester,which can be easily substituted by amino compounds.The main chain of grafting copolymer,poly(L-glutamic acid) was recognized as a biodegradable polymer,and the aniline tetramer side chain,which is similar with polyaniline in electrical chemical properties,enabled the copolymer to gain or lose electron reversibly,i.e.electroactivity.The chemical structures of the copolymers were confirmed by 1H-NMR，UV-Vis spectrum and elemental analysis.The copolymer can be dissolved in DMF,DMSO or alkaline aqueous solution.The UV-Vis spectrum of the copolymer was measured in DMF at different buffer pH values.The aniline tetramer side chain can be oxided to its emeraldine state in the presence of oxidant and doped by protonic acid.The cyclic voltammogram of the copolymer,measured in 1 mol/L HCl aqueous solution,showed that there were two pairs of reversible redox peaks,which correspond to two redox processes.These characters indicated that the graft copolymer showed a good electroactivity.The graft ratio of aniline tetramer was confirmed by both element analysis method and quantitative UV absorbance of the copolymer in its leucoemeraldine state.The graft ratio could reach to upon 40% by appropriate feed ratio,which meant a higher weight percentage of electroactive units compared with those block copolymers previously reported.A new route to build both electroactive and biodegradable polymers was reported,which may have potential application in nerve tissue engineering and some other aspects of biological researches.
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发布时间：2021-03-19
Research Bulletin
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