最新刊期
卷 ， 期 8 ， 2012
- 摘要：A reductively degradable cationic polymer with comb-like architecture was synthesized by a combination of polycondensation and reversible addition and fragmentation chain transfer radical polymerization (RAFT).First,the direct polycondensation of decanediol,3,3'-dithiodipeopionic acid and malic acid was carried out using scandium triflate as catalyst.Due to the chemoselectivity of scandium triflate for esterification,the secondary hydroxyl groups of malic units were not esterified during the polycondensation process,resulting in functional polyester with numerous disulfide bones and hydroxyl groups.Then the pendant hydroxyl groups were modified into dithioester form in the presence of N,N'-dicyclohexylcarbodiimide (DCC) and 4-dimethylaminopyridine (DMAP),to give a macromolecular chain transfer agent,which could be used as multifunctional backbone to prepare comb-like polymer by grafting from method.Finally,the poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) side chains were attached to the backbone via RAFT polymerization of 2-(dimethylamino)ethyl methacrylate.The comb-like architecture of the copolymer was characterized by 1H-NMR and GPC.The reducible degradation of the comb-like polycation was studied in the presence of tributylphosphane as reducing agent,which demonstrated the cleavage of disulfide bonds in the backbone under reductive environment,resulting in low molecular weight PDMAEMA oligomers.This comb-like cationic polymer may have potential applications in gene delivery,which is being investigated in our research group.关键词：Cationic polymer;Comb-like polymer;Disulfide bond;Reductive degradation;PDMAEMA
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发布时间：2021-03-19
Rapid Communications
- 摘要：Chain diffusion is widely existed in the injection molding,welding,and blending of polymer materials.Dynamic rheological technique has been proved to be a very sensitive method for studying the chain diffusion at the polymer/polymer interface.This paper gives a brief introduction of the principle and methodology of dynamic rheological technique and its application on the study of polymer/polymer chain diffusion.Influence of the initial chain-end distribution at the surface before contact on the diffusion mechanism,numberization of asymmetric polymer/polymer interface,mutual diffusion of asymmetric polymer/polymer,effect of molecular weight polydispersity on diffusion at polymer/polymer interface,coupling between flow and diffusion at polymer/polymer interfaces,as well as rheological study on interdiffusion and reaction at polymer/polymer interface in recent years are discussed.Finally,a simple review about application of dynamic rheological technique on interdiffusion at polymer/polymer interface is made.关键词：Dynamic rheological technique;Polymer;Interface;Diffusion
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发布时间：2021-03-19 - 摘要：Electrospinning is one of the most basic techniques for the production of nanoscale fibers.Electrospun nanofibers have excellent properties including small diameter,high surface area to volume ratio and high porosity,thus making them excellent candidates for filtration,catalysis,sensors as well as in biomedical applications.Moreover,multifunctional nanocomposites can be obtained with different functions and elements being hierarchically incorporated into electrospun nanofibers,which will largely broaden their applications in water treatment,healthcare,defense and other technologies.Herein,some recent progress in preparation,structures and properties of hierarchically organized polymer nanocomposites based on electrospun nanofibers are briefly summarized and discussed along with their prospect in practical applications.关键词：Electrospinning;Hierarchical organization;Polymer nanocomposites
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发布时间：2021-03-19
Reviews
- 摘要：Real-time infrared spectroscopy (RT-FTIR) was used to study the effect of chemical structure of oligomer,reactive diluent and the ratio of oligomer and reactive diluent on the initiating activity of camphorquinone (CQ)/1,3-benzodioxole (BDO).The results showed that,urethane dimethacrylate (UDMA) with a low viscosity was prone to chain transfer reaction and had hydrogen donating ability.In the polymerization system with high content of UDMA,UDMA could be used as a competitive hydrogen donor to interact with the exited CQ,which significantly influenced the interaction of exited CQ and BDO.Another commercial oligomer 2,2-bis［4-(2-hydroxy-3-methacryloxypropoxy)phenyl］propane (bis-GMA) with a high viscosity exhibited a high reactivity.When it combined with reactive diluent triethylene glycol dimethacrylate (TEGDMA) in the formulation,a relatively less amount of TEGDMA,i.e.30%,could greatly reduce the viscosity of the monomer system and have little influence on the reactivity of Bis-GMA.At the same time,the Bis-GMA/TEGDMA (70/30,W/W) system with a lower viscosity could greatly improve the mobility of the free radical active species,which was beneficial to improve the initiating activity of CQ/BDO.关键词：Camphorquinone;Benzodioxole;Monomers;Initiating activity
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发布时间：2021-03-19 - 摘要：The living/controlled radical copolymerization of 1,2:3,4-di-O-isopropylidene-6-O-(2'-formyl-4'-vinylphenyl)-D-galactopyranose (IVDG) and 5,6-benzo-2-methylene-1,3-dioxepane (BMDO),was successfully achieved using dicumyl peroxide (DCP) as the initiator and 1-phenylethyl phenyldithioacetate (PEPD) as the reversible addition-fragmentation chain transfer (RAFT) agent at 130℃ in anisole.The number-average molecular weight of the obtained copolymers increased in direct proportion to the monomer conversion,and the molecular weight distribution was narrow (polydispersity index 1.4).Various copolymers of BMDO with IVDG were synthesized by changing the molar ratio of the two monomers in the initial feed using PEPD as chain transfer reagent under RAFT reaction conditions.There was an increase in the molecular weight from 5.2103 to 1.8104 on increasing the molar ratio of IVDG:BMDO from 20:80 to 70:30.In general,the molecular weight of the polymers increased with increase in the amount of IVDG in the copolymers.Moreover,the copolymer composition was determined by taking the ratio of peak areas of aldehyde protons of IVDG to that of of BMDO.It is observed that the mole fraction of BMDO was less in copolymers as compared to that in the initial feed.The result was mostly because the BMDO radical is neighbor to two electron-rich oxygen atoms so as to have lower reactivity as compared to IVDG radical.The copolymer compositions and structural characterization were obtained from 1H-NMR spectroscopy.Degradation behavior of these copolymers was also investigated.Removal of protective isopropylidene groups from the sugar residue in poly(BMDO-co-IVDG) was carried out quantitatively using 88% formic acid at room temperature,yielding a novel amphiphilic copolymer containing both galactopyranose and aldehyde functionalities.These amphiphilic glycopolymers self-assembled into well-defined degradable and biocompatible aldehyde-functionalized polymeric nanospheres in aqueous solutions without recourse to any surfactant.The nanospheres obtained from the resultant glycopolymer are possible to be used as nanoparticle targeted drug-delivery system.关键词：RAFT polymerization;Aldehyde-functionalized glycopolymer;Degradable;Nanosphere
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发布时间：2021-03-19 - 摘要：Polypropylene/acrylonitrile-styrene copolymer (PP/SAN,98/2,96/4,94/6 and 92/8) blend parts were molded via water-assisted injection molding (WAIM) at different water pressures and melt temperatures.The crystal and phase morphologies of the WAIM PP/SAN blend parts were studied by means of polarized optical microscopy (POM) and scanning electron microscopy (SEM).The results showed that the high shear stress and cooling rate occurring during the high-pressure water penetration in the WAIM process could cause the in situ fibrillation of the SAN droplet,followed by the formation of transcrystalline structures at the interface of PP matrix and SAN fiber.For the WAIM 96/4 PP/SAN blend part,increasing the water pressure and lowering the melt temperature were found to be favorable for the formation of transcrystalline structures through increasing the shear stress and relaxation time of PP matrix,respectively.Moreover,it was found that no transcrystalline structures could form at a low SAN content,e.g.,2 wt%.关键词：Water-assisted injection molding;Polypropylene;Acrylonitrile-styrene copolymer;Transcrystallization
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发布时间：2021-03-19 - 摘要：In the aqueous two-phase copolymerization of acrylamide (AM) with quaternary ammonium cationic monomers,such as 2-methylacryloylxyethyl trimethyl ammonium chloride (DMC),in aqueous poly-(ethylene glycol) (PEG) solution a double phase separation process was observed.In order to fix the critical points,the spectrophotometer was employed to detect the transmittance of the copolymerization system on-line.The transmittance curves showed three intervals.At the first interval,the transmittance keeps constant at the beginning,and then drops off quickly.At the second interval,the transmittance stops dropping and begins to increase.And at the last interval,the transmittance stops to keep constant for a moment,and then drops rapidly to nearly zero.When acrylamide was copolymerized with different monomers,the double phase separation process can be observed only for DMC and acryloylxyethyl trimethyl ammonium chloride (DAC).It confirms that the double phase separation is attributed to the cationic nature of DMC and DAC.Then the mechanism of the double phase separation process of the aqueous two-phase copolymerization system was brought up.At the beginning of the aqueous two-phase copolymerization,the growth of copolymer chains is the key factor,so the 1st phase separation occurs when they achieve a critical length.With the copolymerization progressing,the DMC amount in the chains increases and the electrostatic repulsion effect is strengthened,so the precipitated chains begin to dissolve again.However,when the conversion is too high,the molecular weight of the copolymers becomes large,and then the chains precipitated again,so the 2nd phase separation occurs.To validate the mechanism,different inorganic salts were added into the system respectively,and the transmittance curves were investigated.The results showed that the 2nd phase separation process of the aqueous two-phase system disappeared after added some inorganic salts.Therefore,the electrostatic repulsion effect of cationic monomer species is the true reason for double phase separation process.Lastly,the effect of reaction conditions on the double phase separation process was discussed.With the increase of overall monomers amount or PEG amount,the double phase separation process appeared and became obvious gradually,but it disappeared when the amount was too large.With the increase of PEG molecular weight,the double phase separation process became obvious.Raising the copolymerization temperature from 45℃ to 55℃,the double phase separation process was accelerated only.When the mole fraction of DMC is between 0.25 and 0.60,the double phase separation process can be observed,and the first critical conversions were very small,but the second critical conversions were high.When the mole fraction of DMC is above 0.60,the copolymerization finished mainly at the second interval,and the 2nd phase separation is difficult to be observed.关键词：Acrylamide;Quaternary ammonium cationic monomer;Aqueous two-phase copolymerization;Double phase separation;Electrostatic repulsion
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发布时间：2021-03-19 - 摘要：Seven new conjugated D-A copolymers (P1 ~ P7) containing a strong electron deficient pyromellitic diimide (PMDI) unit and a donor unit such as thiophene,bithiophene,benzo［1,2-b:3,4-b'］dithiophene,and dithieno［3,2-b:2',3'-d］silole were synthesized by the Stille coupling reaction.P1 ~ P7possess good solubility in common organic solvents and exhibit strong absorption in the range of 370~600 nm.The electrochemical properties ofP1 ~ P7were investigated by cyclic voltammetry (CV).The CV results indicate that the LUMO energy levels ofP1 ~ P7lie in the range of-3.66~-3.90 eV,while the HOMO energy levels in the range of-5.25~-6.17 eV.The bandgaps ofP1 ~ P7are tunable by incorporating of different donor units.The optical bandgaps forP1 ~ P7calculated from the absorption edge are 2.53~1.94 eV,and the electrochemical bandgaps are 2.45~1.55 eV.Polymers (P1 ~ P7) containing the PMDI unit were applied to bulk heterojunction polymer solar cells (PSCs).High open circuit voltages (Voc) were obtained for these polymers due to their low HOMO levels.Under AM1.5 G illumination (86 mW/cm2),the PSC based on P7 with a pyromellitic diimide unit and a silole unit displayed an open-circuit voltage of 0.72 V,a short-circuit current of 1.22 mA/cm2 and a power conversion efficiency of 0.27%.关键词：Pyromellitic diimide;D-A conjugated polymers;Polymer solar cells
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发布时间：2021-03-19 - 摘要：Seed emulsion polymerization was carried out to encapsulate Fe3O4nanoparticles with poly(N-isopropylacrylamide-co-methacrylic acid) for preparing polymeric microspheres(Fe3O4/P(NIPAM-co-MAA)) possessing magnetic and thermo-sensitive responses.The structure and morphology of microspheres were characterized by wide-angle X-ray diffraction (WAXD),transmission electron microscopy (TEM),dynamic light scattering (DLS),thermogravimetric analysis (TGA),vibrating specimen magnetometry (VSM) and BET specific surface area measurements.Ultraviolet-visible light (UV-Vis) spectroscopy was employed to investigate the drug loading and release behavior of microspheres using rhodamine B (RhB) as a model drug.It is indicated that the diameters of microspheres range from 80 nm to 200 nm,the specific surface area and average pore diameter are about 30.04 m2/g and 24.50 nm,respectively.The polymer content and Fe3O4 content of microspheres are about 73 wt% and 20 wt%,respectively.The saturated magnetization of microspheres reaches 16.49 emu/g,and the volume phase transition temperature (VPTT) is about 37.5℃.The RhB loading amount of microspheres is able to reach 16.38 mg/g.Under alternating magnetic field,the RhB release amount reaches 13.02 mg/g in simulative gastric-juice,and 10.47 mg/g in simulative intestinal-juice,respectively.Therefore,the synthesized polymeric microspheres (Fe3O4/P(NIPAM-co-MAA)) can be used as drug-carrier,and demonstrate good prospect in the targeted drug and drug controlled release.关键词：Thermo-sensitive;Polymeric microspheres;Magnetic induction;Controlled release
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发布时间：2021-03-19 - 摘要：Nanocrystalline cellulose (NCC) is prepared by hydrolysis of microcrystalline cellulose (MCC) with acid.Natural rubber (NR)/NCC compound co-coagulates with NR latex and NCC suspension.Carbon black (CB) is added to NR/NCC composite in the blending process.The mechanical and dynamic properties of NR/NCC/CB,NR/NCC/CB/RH (resorcinol-hexamine complex) and NR/CB were investigated.The results show that NCC disperses uniformly and orientates to the stretching direction in the NR matrix.The Payne effect weakens with the increase of NCC fraction.It indicates that NCC doesnt form a strong filler net and the total filler net in NR/NCC/CB is reduced in comparison with that of NR/CB.At the same time the variation of tan is not obvious.The addition of NCC can improve the mechanical property and the resistance to flex cracking of NR/CB and lower the heat build-up and the permanent set of dynamic compression.The abrasion resistance keeps constant when NCC is replaced by 5~20 phr of CB.DMA shows that the variation of Tg is not obvious,and the tan at 0℃ descends slightly while the tan at 60℃ descends obviously.The Payne effect of the NR/NCC/CB/RH system weakens sharply in comparison with that of the NR/NCC/CB system.And the mechanical property,the resistance to flex cracking and the abrasion resistance improve tremendously.At the same time,the heat buildup and the permanent set of the dynamic compression decrease further.关键词：Nanocrystalline cellulose;Natural rubber;Carbon black;Mechanical properties;Dynamic properties
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发布时间：2021-03-19 - 摘要：The structure and adsorption characteristics of a lignin-type superplasticizer (GCL1-JB).GCL1-JB was prepared by graft sulfonation of alkali lignin from bamboo pulp black liquor and purified by ultrafilter and ion exchange resin.Four GCL1-JB fractions with narrow molecular weight distribution were obtained from gel column chromatography separation and selected to study the structural and adsorption characteristics.Results showed that GCL1-JB had structure features of both high molecular weight and a high degree of sulfonation.The four GCL1-JB fractions had no obvious difference in chemical structure, but with increasing molecular weight,the content of sulfonate groups decreased and the content of aromatic groups increased.Four GCL1-JB fractions were used as polyanions to build up multilayer films on planar substrate by using poly-(diallydimethylammonium chloride) (PDAC) as the polycation.The surfaces of GCL1-JB/PDAC layer-by-layer self-assembled films were generally flat, and their surface roughness was about 1~2 nm.The GCL1-JB with higher molecular weight had a larger adsorbed amount.This phenomenon could be explained in this way.The GCL1-JB with higher molecular weight had a less content of sulfonate groups, inducing less electrostatic repulsion.Therefore, the GCL1-JB with higher molecular weight had larger molecular curling, which caused a larger adsorbed amount.关键词：Bamboo pulp black liquor;Modification of alkali lignin;Layer-by-layer self-assembly;Adsorption
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发布时间：2021-03-19 -
SYNTHESIS OF A 1,3,5-TRIAZINE-CONTAINING AROMATIC DIACID MONOMER AND ITS SOLUBLE AROMATIC POLYAMIDES
摘要：The synthesis,characterization and properties of phenyl-1,3,5-triazine functional monomers and aromatic polyamides are described.A novel aromatic diacid,namely 4,4'-(6-phenyl-1,3,5-triazine-2,4-diyl)dibenzoic acid (PTDA) was successfully prepared by a two-step reaction including Friedel-Crafts reaction and oxidation starting from 2,4-dichloro-6-phenyl-1,3,5-triazine (DCPT).Its chemical structure was characterized by 1H-NMR,FTIR,MS and Elemental analysis.Optimal conditions of the oxidation were chosen on the basis of the yield by using orthogonal experiments with respect to oxidizer content,solvent ratio,heating temperature and reaction time.The reaction,which was achieved at the temperature of 25℃ for 8 h with a CH3COOH/H2SO4 ratio of 10 and a CrO3/PTDA ratio of 4,gave the targeted product with a highest yield of 81.3%.A new aromatic polyamide (PPA) with an inherent viscosity of 0.49 dL/g was obtained by direct phosphorylation polycondensation of PTDA with benzene-1,4-diamine.The obtained polymer possesses good solubility.It is readily soluble in N-methylpyrrolidone, N,N-dimethyl acetamide (DMAc) and sulfolane,and can be easily cast into transparent thin films.Such polymer exhibits glass transition temperature (Tg) up to 315℃,and possesses excellent thermal and thermo-oxidative stability without significant weight loss up to temperatures of approximately 500℃.Its decomposition temperature for 5% mass-loss is in excess of 493℃ in nitrogen and it retains 90% weight at round 520℃.The obtained films exhibits attractable mechanical properties with tensile strengths of 82 MPa,elongation at break of 8.2% and initial moduli of 2.3 GPa.关键词：1;3;5-Triazine- 36
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发布时间：2021-03-19 - 摘要：Carbon black (CB)-filled polyimide (PI) composites were prepared using self-degradated low molecular poly(amic acid) (PAA) as impurity-free dispersant.CB and PAA/N-methyl-2-pyrrolidone (NMP) solution were milled in ball miller.The impurity-free dispersant was prepared in the process of in situ degradation of PAA by high-energy milling process,which was active to carbon black (CB) surface.The effect of PAA modification on the CB particles was researched by Raman,IR and UV-Vis.TEM observation showed that the PAA modified CB particles dispersed uniformly in the mixtures with an average CB size of about 200 nm.The toughness,tensile strength and the reproducibility of resistivity for resulted CB/PI composite films were greatly improved.The elongation of resulted CB/PI films was raised at least 50%,and sample-to-sample variation of elongation was decreased from 17% to 11%.The tensile strength variation range was reduced from 12 MPa to 5 MPa.Resistivity variation range was decreased from two orders down to an order.The molecular weight of PAA added in milling progress played an important role on the dispersion of CB.The dispersion uniformity of CB in PI matrix was greatly improved as the increase of PAA molecular weight.关键词：Polyamic acid;Carbon black;Nano-dispersion
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发布时间：2021-03-19 - 摘要：After MgCl2 was dissolved in ethanol with the ratio of 1:20 in mole at 120℃,the solution was cooled to 70℃ and transferred to the cooling liquid consisting of n-hexane (30 mL) and wax (0.3 g) at 0℃.Precipitate was produced.Filtrated and washed with n-hexane,the residue was dried by vacuum at 50℃,and MgCl2-CH3CH2OH particles were obtained.The size of the particles determined by TEM was at the range from 30 nm to 100 nm.The nano-sized particles of MgCl2-CH3CH2OH could become nano wires by self-assembly technology at room temperature.WAXD results showed that the crystallinity of the obtained nano-sized MgCl2-CH3CH2OH particles became poor,just a broad and weak signal at 2=32~35 was observed,while MgCl2 showed four sharp signals at 2=15,30,35 and 50.The obtained particles were useful as support for preparing nano-sized Ziegler-Natta catalysts.It was confirmed that the prepared catalysts may efficiently polymerize ethylene to form polymer particles with 200~300 nm or 2~4 m in diameter,respectively.关键词：MgCl2-CH3CH2OH complex;Nano-sized particle;Support;Ziegler-Natta catalyst;Nano-sized PE particle
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发布时间：2021-03-19 - 摘要：Diblock copolypeptides of poly(-benzyl-L-glutamate)-b-poly(-dodecyl-L-glutamate) (PBLG-b-PDLG) were synthesized by using the ring opening polymerization of N-carbonyl anhydride (NCA) method.N-hexylamine was used as the initiator,and the reaction was successfully operated in chloroform at 0℃ by adding the second NCAs sequentially after purification of the first segment of PBLG with amino terminal.The chemical contents of PBLG-b-PDLG were confirmed by 1H-NMR,which exhibits signals corresponding to the two different segmental side chains.The relative molecular mass and distribution were characterized by GPC,and the molecular weight distribution of the final PBLG-b-PDLG can be achieved to only 1.07~1.09.The secondary structure was examined by IR spectrum,which indicated the material exhibited -helical rod-like structure.The thermal behaviors of two block copolypeptides depend on the chemical composition,and both of them show thermotropic nature around 100℃ observed by polarizing microscope.No elimination of molecular alignment in magnetic orientated film takes place when heating above 100℃,therefore the phase structure of block copolymers differs from the random one of poly(-benzyl-L-glutamate-co--dodecyl-L-glutamate) exhibiting cholesteric twisting structure.The fan-shaped texture was observed in lyotropic solutions of the copolypeptide,indicating the smectic ordering existence.This appearance was believed to be contributed by its narrow molecular weight distribution.关键词：Polypeptides;Block copolymer;N-carboxyanhydrides;Polydispersity;Smectic liquid crystals
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发布时间：2021-03-19 - 摘要：A new aromatic diamine monomer,,-bis(4-amino-3,5-dimethylphenyl)phenylmethane (BADP),was synthesized via a straightforward one-step procedure with high yield.FTIR and 1H-NMR were employed to confirm the designed structure.In order to maintain the excellent thermal properties and improve the solubility of polyimides,a series of aromatic polyimides were successfully synthesized via one-step polymerization method in anhydrous N-methyl-2-pyrrolidone (NMP) by a reaction of 2-(4-aminophenyl)-5-aminobenzimidazole (BIA),the synthesized BADP and one of four dianhydrides (PDMA,BPDA,BTDA and ODPA).The structures of copolyimides were confirmed by FTIR,showing the characteristic peaks of polyimides at 1780,1720 and 725 cm-1.The UV-Vis measurements indicated that the cut-off wavelengths were at 360~380 nm without consideration of relatively weak transmittance in the range of 310~360 nm.As we expected,the polyimides exhibit excellent solubility,and can be dissolved in normal solvents such as NMP,DMAc or CHCl3.The soluble polyimides show a relatively higher glass transition temperature (Tg 410℃) measured by dynamic mechanical analysis (DMA) and a high initial decomposition temperature (Td500℃) in TGA and more than 55 wt% residues at 900℃ under nitrogen atmosphere.Moreover,the tensile strength of polyimides is 61~100 MPa.The soluble polymers can be used as high performance resins or processed into high performance fibers.关键词：Polyimides;One-step synthetic method;Soluble;Thermal stability
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发布时间：2021-03-19 - 摘要：A series of block ionomers containing sulfonated poly(phthalazinone ether ketone) hydrophilic segments and poly(fluorene ether sulfone) hydrophobic segments were synthesized via two-pot two-step nucleophilic polycondensation.Bis(4-chlorophenyl) sulfone and 9,9-bis(4-hydroxyphenyl) fluorene (BHF) were used as comonomers for hydrophobic blocks.Bisphthalazinone and sulfonated 4,4-difluorobenzophenone (SDFBP) were used to synthsize hydrophilic blocks.Ionomers with different segment sizes were synthesized by adjusting the molar ratios and prepolymerization and polycondensation.The structure of the ionomers was characterized by 1H-NMR and FTIR.The spectra and data indicated that these ploymers were in accordance with the designed backbone structure well.The TGA measurements of the ploymers were performed under a nitrogen atmosphere from 50℃ to 600℃,and results demonstrated that the so-made polymers exhibited good thermal stabilities with 5% weight loss temperature over 250℃.The polymers were soluble in common aprotic solvents,such as DMSO,DMAc,dimethylformamide (DMF),N-methylpyrroridone (NMP) and tetramethylene sulfone.The inherent viscosity of the synthesized polymers ranged from 0.40 dL/g to 0.71 dL/g,demonstrating high molecular weight of the resulted polymers.The water uptakes of the copolymers with blocks of varying size were moderate.Moreover,these copolymers demonstrated greatly improved oxidative stabilities and hydrolysis resistance.Polymers 8c ~ 8e with block size bigger than eighteen repeat units were undegradable after 720 h and unhydrolyzable after 480 h.The hydrolysis resistance of the resulted membrances were much better than that of Nafion 117.The copolymers had strong alcohol resistance at refluxing temperature.The methanol penetrabilities of the prepared membranes varied from 0.2310-6 cm2/s to 0.2810-6 cm2/s,while that of Nafion 117 was 1.3210-6 cm2/s under the identical conditions.Especially,polymer 8e gave the proton conductivity of 1.8310-3 S/cm at 80℃.It is a promising proton exchange membrane material for proton exchange membrane fuel cell using methanol or ethanol as fuel.关键词：Ionomer;Poly(ether sulfone)-b-poly(ether ketone);Fluorene bisphenol;Phthalazinone;Proton exchange membrane fuel cell
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发布时间：2021-03-19 - 摘要：The suspension polymerization of vinyl chloride (VC) was carried out at 40~70℃ in the composite dispersant system composed of poly(vinyl alcohol) and hydroxypropyl methylcellulose,with N-tert-butyl--phenylnitrone (PBN) as the source of nitroxide radicals and -cumyl peroxyneodecanoate (Lup188) as initiator.The effects of the concentration of Lup188,the concentration of PBN and polymerization temperature on the polymerization kinetics,molecular weight and polydispersity index (PDI) of poly(vinyl chloride) (PVC) were investigated in detail.The kinetics of VC suspension polymerization was monitored by gravimetric method while the molecular weight and its distribution of PVC synthesized were determined by gel permeation chromatography.The results showed that the chain propagation in VC polymerization could be efficiently controlled by adding suitable amount of PBN and Lup188 at a reasonable temperature.The optimal molar ratio of VC,Lup188 and PBN was 1000:7:1.As the polymerization temperature increased,the polymerization rate of VC first increased and then decreased,which was different from the mechanism of common radical polymerization.Simultaneously,the molecular weight of synthesized PVC first increased and then decreased,while the PDI first decreased and then increased.The optimal polymerization temperature was 50℃.At this temperature,the PDI of PVC was 1.7~2.0 and did not change significantly in the range of conversion 3%~50%,which was considerably lower than that in common radical polymerization.However,with the conversion increasing further,the PDI of PVC increased.关键词：Nitroxides;Vinyl chloride;Controlled/living radical polymerization;Suspension polymerization
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发布时间：2021-03-19 - 摘要：Two amphiphilic biodegradable block copolymers,poly(ethylene glycol)-b-poly(lactide-co-carbonate),were prepared and then conjugated with paclitaxel (PTX) and folic acid (FA),respectively,to form polymer-PTX conjugate and polymer-FA conjugate.These two conjugates were co-assembled into composite nanomicelles with an average diameter of ca.50 nm,a PTX content of 27 wt% and a FA content of 1.4 wt%.Human ovarian cancer SKOV3 cells were cultured.MTT assay and flow cytometry analysis showed that Taxol,M(PTX) and FA-M(PTX) could inhibit the growth of SKOV3 cells at a PTX concentration of 10 g/mL,M(PTX) and FA-M(PTX) were more efficient than Taxol.Xenograft subcutaneous SKOV3 cancer models were constructed in balb/c mice.Inhibition of the tumor growth by Taxol,M(PTX) and FA-M(PTX) was examined.At a dosage of 20 mg/kg,the tumor volume measurement,the tumor weight measurement on the 9th day and the survival curve all showed that Taxol,M(PTX) and FA-M(PTX) could inhibit the growth of the SKOV3 cancers,in the order of Taxol
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发布时间：2021-03-19
Research Article
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