最新刊期
卷 ， 期 5 ， 2014
- 摘要：Conjugated polymers have received more and more attention due to their widespread applications in the field of organic optoelectronics and information displays.Most of the conjugated polymers are synthesized by transition-metal-complex catalyzed coupling reactions,which usually follow the step-growth mechanism,and require high purity monomers,high temperature and long reaction time to achieve samples of high molecular weight.However,the molecular weight,polydispersity and chain-ends of the resulting polymers are in general poorly controlled.Catalyst-transfer polycondensation is a novel method for the synthesis of well-defined conjugated polymers.Because the catalyst can transfer through an intramolecular process to the propagating chain end that leads to the coupling reaction of the monomer with the polymer,such polymerization follows the chain-growth mechanism.With this newly developed method,various conjugated polymers,including homopolymers,copolymers,polymer brushes and hairy particles with controlled molecular weights and relatively narrow polydispersities (PDIs),have been prepared.In this progress report,the recent advances made in the field of catalyst-transfer polycondensation have been summarized.The problems existed are pointed out and the future trends are discussed.关键词：Catalyst-transfer polycondensation;Chain-growth mechanism;Conjugated polymers;Copolymers;Conjugated polymer brushes
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发布时间：2021-03-19 - 摘要：Click reactions,introduced by Sharpless,are a series of reactions with the characteristics of high efficient,reliable and high selectivity.They are widely used in the synthesis of topological polymers.To date,the most studied click reactions are Cu (I) catalyzed azide-alkyne cycloaddition (CuAAC),Diels-Alder reaction,thiol-ene/yne reaction and nitroxide radical coupling reaction.The combination of multiple click reactions broadens the synthetic methods of well-defined polymers with various topologies.In this review,the application of combination of multiple click reactions in the synthesis of well-defined polymers in the last a few years is briefly summarized,and the prospects of multiple click reactions in this area are also discussed.关键词：Click chemistry;Multiple click reactions;Topological polymers;Combination;Living radical polymerization
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发布时间：2021-03-19
Reviews
- 摘要：The objective of this study was to alleviate the acidity of PLGA nanofiber degradation in vitro by introducing the basic amino acid Lysine (Lys) into the PLGA nanofibers.PLGA and PLGA/Lys composite nanofibers were prepared via electrospinning,and the morphology,thermodynamic and mechanical properties of these nanofibers were characterized by SEM,DSC and mechanical testing,respectively.Release profiles of the Lys from the PLGA-based composite nanofibers were thereafter determined.Morphology of the degraded nanofibers and pH of the PBS solution,in which PLGA and PLGA/Lys nanofibrous mats were soaked at 37 ℃ for up to eight weeks,were assessed to detect the degradation behavior.Finally,cytotoxicity was performed by culturing vascular smooth muscle cells (SMCs) with fluid containing degraded product after eight weeks of degradation.It was found that the release kinetics of Lys from the electrospun PLGA/Lys nanofibers was Lys content dependent.Incorporation of Lys enhanced the degradation process of PLGA and mitigated the decrease of PBS solution pH (acidity).PLGA nanofibers containing 2% Lys are capable of maintaining the pH value between 7.4 and 6.7.Proliferation of SMCs was hindered in the presence of acidic products.But the SMCs grew well in the solution containing degraded products and Lys.关键词：Poly(lactic-co-glycolic acid);Lysine;Electrospinning;Degradation;Cytocompatibility
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发布时间：2021-03-19 - 摘要：The well-ordered 2D hexagonal structure FDU-15 mesoporous polymer with the P6mm space group has been synthesized by soft template method.Novel sulfonic acid group-functionalized FDU-15 mesoporous polymer solid acid (FDU-SO3H) catalyst was successfully prepared through vapour-phase transfer sulfonation of FDU-15.Various techniques such as X-ray diffraction (XRD),scanning electron microscopy (SEM) and elemental analysis have been adopted to track the functionalization processes,and to characterize the physicochemical properties of the FDU-SO3H.The FDU-SO3H catalyst was tested in the Biginelli reactions of aromatic aldehydes,ethyl acetoacetate and urea (or thiourea) under solvent-free conditions.In order to find the optimal reaction conditions for the FDU-SO3H catalyst,the effects of additive sequence,solvents,reaction substrates in the Biginelli reaction have been investigated.3,4-Dihydropyrimidinones/thiones and their derivatives have been synthesized under the optimum reaction conditions.A high yield of 3,4-dihydropyrimidin-2(1H)-ones as 91% was achieved when Biginelli reaction of benzaldehyde,ethyl acetoacetate and urea was carried out at 90 ℃ for 1 h under solvent-free conditions.The FDU-SO3H catalyst exhibited similar catalytic activity even after four cycles for Biginelli reaction of benzaldehyde,ethyl acetoacetate and urea.The possible mechanisms of Biginelli reaction have been discussed.The experimental results verified that the FDU-SO3H was able to act as a highly active,eco-friendly,stable and resusable heterogeneous catalyst.关键词：Mesopolymer;Solid acid;Biginelli reaction;One-pot
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发布时间：2021-03-19 - 摘要：This paper presents an approach to prepare polysiloxane-based conductive composites filled with low-cost silver coated copper (Ag-coated Cu) microscale flakes by using the hyperbranched poly(amine-ester) (HBP3-MA) as modifier which is obtained by the reaction between the hyperbranched poly(amine-ester) (HBP3-OH) with terminal hydroxyl and maleic anhydride.The structure of the HBP3-MA was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR).Curing condition of the compound system was studied by differential scanning calorimetry (DSC) since HBP3-MA was involved in the curing reaction of polysiloxane.The structural morphology (the size and dispersion) of in situ reduced AgNPs and the composite system was studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM).Also,conductivity mechanism of the composites reinforced by metal nanoparticles was discussed.At the curing temperature,silver acetate decomposed and silver nanoparticles (AgNPs) were in situ generated in the polymer matrix.The low temperature sintering of AgNPs anchored on the surface of Ag-coated Cu flakes enhanced the interfacial bond of Ag-coated Cu flakes and decreased the overall contact resistance.Last,the conductivity and shear strength of the composites were studied.When the content of silver acetate was 4.4 phr,the optimum volume resistivity and the shear strength were achieved,which were 3.610-3cm and 0.32 MPa,respectively.关键词：Hyperbranched poly(amine-ester);Low temperature sintering;Nano-silver;Polysiloxane;Volume resistivity
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发布时间：2021-03-19 - 摘要：The synthesis of poly(1,4-butylene carbonate) (PBC) catalyzed by TiO2-SiO2(PVP-gel) was studied via a two-step melt transesterification of diphenyl carbonate and 1,4-butanediol.After pre-polymerization of diphenyl carbonate and 1,4-butanediol in the standard atmosphere,the vacuum condensation reaction was operated.The PBC was characterized by IR,NMR,GPC and DSC.The experimental results showed that the optimum conditions of the reaction were as follows: the reaction time and reaction temperature were 2 h and 220~230 ℃ (N2 protection),respectively,in the standard atmosphere pre-polymerization step.The reaction time,reaction pressure and the catalyst dosage were 2 h, 300 Pa and 0.15 wt%,respectively,in the vacuum condensation step.The properties of the PBC prepared in optimum conditions,were as follows:[]was 1.12 dL/g,the Mn was 49000,the Mw was 101000,the polydispersity index was 2.07,the Tg was -32.32 ℃,the terminal hydroxyl content was 6.210-4 mol/g and the residue of the phenol was 5.26 wt%.The polymerization degree of PBC can be controlled by the evaporation rate and yield of phenol under the technological conditions.And the phenol by-product was recycled almost completely.关键词：Diphenyl carbonate;Poly(1,4-butylene carbonate);Melt-transesterification;1,4-Butanediol
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发布时间：2021-03-19 - 摘要：A pH-responsive controlled release model for bortezomib (BTZ) based on catechol borate ester bond has been constructed successfully by poly(ethylene glycol) (PEG),dodecylamine (DDA) and dopamine (DPA)-modified poly itaconic acid (PIA) (PIA-PEG-DDA-DPA-BTZ).Its structure was characterized by nuclear magnetic resonance (NMR).The result showed that the targeted products were prepared successfully.The PIA-PEG-DDA-DPA-BTZ was then made into micelles.The sizes of the micelles formed by the polymer were tested by dynamic light scattering (DLS),and observed under atomic force microscope (AFM).According to the test,the micelles showed a spherical and monodispersed construct with very small diameter of about 35 nm.The critical micelle concentration (CMC) value was 2.5410-3 mg/mL via pyrene fluorescence method.The standard curve of BTZ was portrayed based on the characteristic absorption peak of BTZ at 300 nm in UV-Vis absorption.The cumulative release rates of BTZ conjugates were then studied at pH 5.0 and pH 7.4,and the release behavior at pH 5.0 fits the first order kinetics model,Q=61.65866-62.13481e-0.32544t,the coefficient of determination was 0.99798.The cell viability studies showed that the micelles had a quite significant inhibitory effect on cancer cells which is close to that of the pure bortezomib.The pH-responsive controlled release model has the potential of becoming a promising diagnostic tool in clinical application for cancer treatment.关键词：Bortezomib;Catechol borate ester bond;pH-sensitive;Model of drug release
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发布时间：2021-03-19 - 摘要：Radical emulsion polymerization in the presence of 3-mercapto hexyl methacrylate (MHM) as the chain transfer monomer has been carried out in this study.Potassium persulfate was used as the initiator,and sodium dodecyl benzene sulfate was used as the emulsifier.The obtained polymers were characterized using 1H-NMR and triple-detection size exclusion chromatography.The primary chain length and the average MHM content per primary chain can be adjusted by the polymerization parameters.At the same feed ratio of monomer/branching agent,the molecular weight of the primary chain and its average MHM content will be increased with increase of emulsifier concentration and decrease of polymerization temperature or initiator concentration,which is beneficial to preparing branched vinyl polymers with high molecular weights and relatively narrow polydispersities because of high conversion of the primary chain into branched molecules.Excess high emulsifier concentration,low polymerization temperature or low initiator concentration will result in gelation because of excess coupling reaction between branched molecules.Compared with results reported in the literature,branched polymers with considerably higher molecular weights and relatively narrower polydispersities have been obtained without gelation at high monomer conversions because no primary chains remain.关键词：Chain transfer monomer;Branched polystyrene;Radical polymerization;Emulsion polymerization
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发布时间：2021-03-19 - 摘要：Poly(N-isopropylacrylamide) (PNIPAM) grafted polyamidoamine (PAMAM) was used as stablizer in gold colloid synthesis,and water was used as solvent by using in situ synthesis method.The prepared gold colloid showed different responsive behavior under different temperature both in the aspect of its photo-thermal properties and drug controlled release properties.1H-NMR and FTIR were used for characterizing the polymers on the gold colloid.Transmission electronic microscopy (TEM) was used for the core size determination and it revealed that the core size varied under different synthesis conditions.UV-Vis spectrum was used for its surface plasmon resonances properties study and the results showed that the maximized adsorption was different for gold colloids with different ligand densities.Further study on lower critical solution temperature (LCST) was carried out with UV-Vis spectrum and the results showed that the LCST of the polymer precursor was enhanced after the introduction of gold cores.The LCST of polymer precursor was about 33.5 ℃,and that of the gold colloids were both above 38 ℃.The morphology of the gold core after phase transition detected by TEM showed that severe aggregation occurred after phase transition,which endowed the gold colloids the thermal responsive photo-thermal conversion ability,as a result of that,the side effect of photo-thermal treatment could be reduced significantly.Laser was used to investigate the photo-thermal behavior of the gold colloids and the results showed that significant photo-thermal conversion process occurred for all of gold colloids after phase transition (the temperature after laser excitation increased sharply from 25 ℃ to 43 ℃ and 48 ℃,respectively).The drug release study indicated the controlled release behavior of the gold colloids under thermal stimuli.All these results showed that this kind of thermo-responsive gold nanospheres has great potential to be used in both photo-thermal field and controlled drug release field.关键词：Gold colloid;Thermo-responsive polymer;Photo-thermal conversion;Non-covalent carrier
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发布时间：2021-03-19 - 摘要：A series of cation exchange membranes based on multiblock suflonated poly(arylene ether sulfone)s (bSPAES) were prepared successfully and used as the separators in the microbial fuel cell (MFC) systems.The properties of the membranes relative to the MFC applications were investigated in details.After introduction of the rigid fluorenyl in the hydrophilic moieties of bSPAES,the corresponding membranes exhibited much better dimensional stability and hydrolytic stability.bSPAES showed isotropic performance in a range of 10%~20% in size change and 81~140 mS/cm of proton conductivity,which were much higher than those of commercial product of ULTREX CMI-7000.After 1000 h MFC operation,almost no changes were observed for the proton conductivity of bSPAES membranes.Hydrolytic stability test in 100 ℃ water for 24 h showed that the weight loss was between 1.5% and 6.3%.The maximum power density of MFC increased with the block length increasing.Comparing with the ULTREX CMI-7000 membrane,the bSPAES membranes exhibited much higher MFC performances,and the maximum power density for bSPAES(30/30) reached to 705 mW/m2.关键词：Microbial fuel cell;Multiblock sulfonated poly(arylene ether sulfone);MFC performance
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发布时间：2021-03-19 - 摘要：Three kinds of initiators (sodium hydroxide,sodium caprolactamate and caprolactam magnesium bromide) were selected to react respectively with microcrystalline cellulose (MCC) under vacuum at 150 ℃ for analyzing the mechanism of the severe retardation and discoloration in the reactive processing of anionic polyamide-6 and ramie fiber,with using conventional sodium initiators.Then the changes of the sodium caprolactamate (C10) and MCC before and after reaction were analyzed using Fourier translation infrared spectroscopy (FTIR),atomic absorption spectroscopy (AAS),X-ray diffraction (XRD) and nuclear magnetic resonance spectroscopy (NMR),and it was concluded that the retardation and discoloration were mainly caused by the special byproducts generated from the peeling reaction of cellulose in alkaline and high-heat conditions,which were easy to react with anions dissociated from initiator,resulting in the consumption of the initiators,so as to make the end of polymerization of anionic polyamide-6.In addition,the initiator caprolactam magnesium bromide (C1),due to low-activity and weak-alkalinity,weakened the peeling reaction and the reaction with the active groups on the byproducts,and thus the retardation and discoloration were improved significantly,which were the most important challenge during the reactive processing.Finally,the goal was achieved for manufacturing the ramie fiber-reinforced anionic polyamide-6 composites by reactive processing.关键词：Anionic polyamide-6;Ramie fiber;Reactive processing;Peeling reaction
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发布时间：2021-03-19 - 摘要：A type of 2,7-carbazole and fluorene based alternating conjugated polymer,poly［(9,9-dioctyl)-2,7-fluorene-co-2,7-N-dodec-carbazole］ (PF27Cz),was synthesized by Suzuki coupling reaction.With the addition of I- (aqueous NaI),the fluorescence of PF27Cz (in THF) was sequentially quenched.The apparent color of PF27Cz turned from colorless to light yellow within the titration process.The heavy-atom effect of I- is the possible reason for the alteration of PF27Cz's optical properties.The presence of other common anions did not bring similar influence toward the optical properties of PF27Cz as was done by I-.The detection limit of I- by PF27Cz reaches ca. 9.010-8 mol/L (evaluated by the analysis of the relationship between probe's fluorescence and I- ' s concentration).By taking advantage of the strong association constants and high matching ratio between Hg2+and I-,the fluorescence of PF27Cz-I-assembly restored gradually with the addition of incremental Hg2+,accompanied by the recovery of solution's apparent color (from light yellow to colorless).The detection limit of PF27Cz-I- toward Hg2+ can be evaluated by analyzing the detailed fluorescence alteration within the titration process,to be ca. 1.610-8 mol/L.When the concentration of Hg2+ reached ca. 6.810-5 mol/L,the fluorescence of PF27Cz-I- almost reached the initial value of pristine PF27Cz.Competition experiments about the interference of background metal ions against Hg2+ suggest that the presence of background metal ions just brought slight interference.Results show that PF27Cz can act as a sensitive,high-selective and anti-interfacial turn-on type optical probe for Hg2+.关键词：2,7-Carbazole;Conjugated polymer;Optical probe;Fluorescence turn-on;Mercury ion
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发布时间：2021-03-19 - 摘要：A new type of biodegradable micelles for glutathione-mediated drug delivery was developed on the basis of amphiphilic polyurethane (PCL-SS-MPEG) with disulfide linkages between the hydrophobic and hydrophilic moieties.The disulfide contained amphiphilic polyurethane was synthesized as follows:first,cystamine capped linear prepolymer polyurethane was synthesized with poly(-caprolactone diol) (PCL) as soft segment,lysine dⅡsocyanate (LDI) and cystamine as hard segment,then epoxy group of -methoxy--epoxy propyl glycol (EO-MPEG) reacted with amine of cystamine capped linear prepolymer polyurethane.The molecular weight of polyurethane was characterized by GPC,the structure was characterized by 1H-NMR and FTIR.Polyurethane micelles was prepared by dialysis method,the critical micelle concentration was 5.610-3g/L measured by fluorescence techniche.TEM analysis showed that the morphology of micelles is spherical,DLS analysis showed that the average particle size of micelles was 82 nm,both TEM and DLS analysis indicated that PCL-SS-MPEG was able to self-assemble into micelles in aqueous solutions benefitting from its amphiphilic structure.Reduction-triggered destabilization of PCL-SS-MPEG was determined by DLS measurements,the results showed the size of micelles significantly increased under 10 mmol/L glutathione,indicating that the micelles had reduction sensitive characteristics.Finally,a hydrophobic anti-cancer drug methotrexate (MTX) was used as a model drug to study drug release in glutathione,the results indicated glutathione can accelerate the release of the drug by breaking the disulfide bridge linkages and destabilizing the micelle structure.This result shows that the polyurethanes are promising to be used as reduction-stimulus materials in drug delivery.关键词：Polyurethane micelles;Reduction-sensitive;Drug carriers
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发布时间：2021-03-19 - 摘要：Carbon nanospheres (CSs) treated with Grignard reagent were used as carrier,which reacted with TiCl4to form supported Ziegler-Natta catalyst.In the presence of AlEt3,this catalyst catalyzed ethylene polymerization to obtain PE/CSs composites in situ.The catalytic activity for ethylene polymerization was up to 5.7106 gPE/(molTi h) and the weight average molecular weight of the obtained polymer was 4.9105.As characterized by TEM and SEM,the particles of obtained composites were spherical with diameters of about 1 m,furthermore,they featured a core-shell structure as expected.The dielectric analysis results indicated that compared with normal polyethylene,by the introduction of carbon nanospheres the PE/CSs composites dielectric properties experienced an obvious increase,which improved the anti-static function of PE.The dielectric result showed a slight decline of the dielectric constant of PE/CSs composites with increase of the polymerization time,and lower dielectric loss was also observed due to the decrease of CSs content in PE/CSs composites.Moreover,the crystalline properties and thermal stability of the PE/CSs composites were determined by WAXD,DSC and TGA.It turned out that PE/CSs composite possessed good crystalline properties and thermal stability.关键词：Carbon nanospheres;Supported Ziegler-Natta catalyst;PE/Carbon nanosphere composite;Core-shell structure
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发布时间：2021-03-19 - 摘要：Polyacrylonitrile (PAN) filaments were braided into a braid hollow tube for membrane reinforcement via two-dimensional weaving techniques.Polyacrylonitrile and polyvinylidene fluoride were used as membrane-forming polymers,N,N-dimethylacetamide (DMAc) as solvents and polyvinyl pyrrolidone (PVP) as an additive.PAN filaments braid tube reinforced homogeneous PAN hollow fiber membranes and enhanced heterogeneous polyvinylidene fluoride (PVDF) hollow fiber membranes were prepared by concentric circles squeezing-coating spinning method.Results showed that for the PAN filaments braid tube reinforced hollow fiber membranes the rupture strength was up to 75 MPa or more,and the interface adhesion between reinforcement and separation surface had a good combination in the range of 10% elongation rate.The structure of the separation surface was similar to the structure of asymmetric membranes.The casting solution could penetrate into the gap between fiber bundles of the braided tubes,and did not affect the permeability of the membrane.With polymer concentration increasing,the membrane flux was decreased,and the retention rate of BSA was increased.With additive PVP concentration increasing,the membrane water flux was increased and then decreased,in addition,maximum was at 8%; but the retention rate of BSA was increased monotonically.The results also showed that the interface adhesion of the filaments braid tube reinforced homogeneous hollow fiber membranes were better than that of the heterogeneous ones.关键词：Polyacrylonitrile;Polyvinylidene fluoride;Braid tube;Hollow fiber membrane;Reinforced
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发布时间：2021-03-19 - 摘要：PANI nanofibers oxidized by FeCl3 were employed as the supports for the immobilization of horseradish peroxidase (HRP) via covalent immobilization.These PANI-HRP enzymes have been characterized using scanning electron microscopy (SEM),Fourier transform infrared (FTIR) spectroscopy and UV-Visible spectroscopy.SEM images show that the diameters of PANI-nanofibers are in the range of 20~30 nm.The nanofibers become larger and rough after immobolization of HRP.FTIR and UV-Vis demonstrate that horseradish peroxidase can dope into PANI supports as the dopants.This method is simple,fast,and the activation of PANI support is not necessary.The maximum amount of HRP loading on PANI is 150 g/mgPANI for undoped-PANI,90 g/mgPANI for doped-PANI,respectively.Comparing with the free HRP,the optimum working pH,the optimum working temperature and thermal stability of PANI-HRP were significantly improved.No obvious activity loss was observed after 7 weeks storage at 4 ℃,and 80% of the initial activity could still remain even after 6 times usage.These results demonstrate that PANI nanofibers as a carriers for HRP enzymes have great potential applications.关键词：Polyaniline;Nanofibers;Horseradish peroxidase;Immobilization;Enzyme activity;Stability
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发布时间：2021-03-19 - 摘要：Poly(vinyl alcohol) (PVA) hydrogels were prepared under different conditions such as the various concentrations,solvents,the times of freeze-thaw circles and the introduction of polyethylene oxide (PEO).Effect of these preparation parameters on the frictional behavior of PVA hydrogels sliding on a glass surface was investigated in detail.The results show that mixed solvent of water and dimethyl sulfoxide facilitates the formation of a more uniform gel network and thus increases the strength of hydrogels.Moreover,the strength of hydrogels can also be increased by increasing freeze-thaw circle times and adding ultrahigh molecular weight PEO due to the formation of a dense and uniform network.On the other hand,stiff hydrogels with high modulus show a higher frictional stress at a low sliding velocity compared with soft hydrogels; however,it is fast to get into the hydrodynamic lubrication and exhibits a lower frictional stress at a high sliding velocity.The velocity (10-1 ~100m/s) is approximately the cartilage sliding velocity of the knee when people are walking.In addition,PEO molecular brush can reduce the frictional stress of PVA sliding against glass at high sliding velocities to some extent,however,at low sliding velocities,the reducing of frictional stress depends on the concentration of the added PEO.It suggests that increasing the modulus of hydrogels is more effective in reducing the friction at high sliding velocity region than that of introducing PEO with ultrahigh molecular weight.关键词：Polyvinyl alcohol hydrogel;Polyethylene oxide;Modulus;Frictional behavior
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发布时间：2021-03-19
Research Article
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