最新刊期
卷 ， 期 12 ， 2010
- 摘要：Alginate possesses many favorable properties required for biomaterials such as biocompatibility and gelation under gentle conditions.The critical behaviour of the sol-gel transition in aqueous alginate solutions induced by cations was affected by many factors,including the molecular weight and molecular structure sequence of alginate and the kind of cations.The critical exponents suggested two categories of the gelation as growth and crosslink according to molecular size in the solution just before the gelation.Alginate is widely used in tissue-engineered cartilages and drug controlled release.This review seeks to condense information in developing materials for these applications.关键词：Alginate;Gelation;Tissue engineering;Cartilage;Drug controlled release
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发布时间：2021-03-19 - 摘要：This paper summarizes the current research results on the chain conformations of the fungi polysaccharides in solution and characterization methods.The molecular weight,particle size,and chain conformation of various polysaccharides exacted from mushrooms including Lentinus edodes,Poria cocos,Ganoderma lucidum,Auricularia auricula-judae,Xanthomonas,Schizophyllan,etc.in solution are introduced,and the relationships between the bioactivity and the chain conformation are outlined.It is concluded that extended chain,charged groups and moderate molecular weight of the polysaccharides are beneficial to enhance the antitumor activities,as results of the increasing the interaction between polysaccharide molecules and immune system.It is indicated the importance of understanding the relationship between polysaccharide chain conformation and biological activity.Polysaccharides mainly exist as random coil,double helix,triple helix,the worm-like and rod-like chain conformations,as well as aggregates in solution,depending on the type of monosaccharide and glycosidic link,the branch chain structure and intermolecular interactions.The major characterization methods include light scattering,viscosity,microscopy(TEM,SEM and atomic force microscope),microcalorimetry and small angle X-ray scattering.In addition,the polysaccharides solution theory and the calculation expression of chain conformation parameters are represented and discussed.
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发布时间：2021-03-19 - 摘要：As the most abundant natural polymer on the earth,cellulose has many attractive properties such as renewability,biodegradability,biocompatibility,and broad chemical-modifying capacity.Therefore,cellulose has been considered as the sustainable raw material of energy and chemical engineering in the future.Nowadays,cellulose has attracted a worldwide attention as a renewable resource that can be converted into high value products,in which specific attention has been paid on cellulosebased advanced functional materials.Based on about 360 relevant papers published during the past 5 years,this review highlights recent progress in cellulose-based advanced functional materials from the view of fabrication methodologies.The various cellulose-based functional materials,such as fiber materials,membrane materials,photoelectric materials,hybrid materials,smart materials,and biomedical materials,are described,along with their preparation,properties and applications.Finally,a perspective on this promising family of materials and the research that needs to be done in the future are briefly discussed.It is hoped that this review work will stimulate research and collaborations that will lead to significant progress in this area.关键词：Cellulose;Advanced functional materials;Composites
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发布时间：2021-03-19 - 摘要：Electroactive conducting polymers(ECPs),such as polypyrrole(PPy) and polyaniline(PANi),have shown potential applications in the biomedical field.ECP has been the focus of attentions by scientists,biological,tissue engineering as well as medical professionals.The current researches concentrate on biocompatibility,tissue engineering,protein separation,DNA repair adsorption,controlled drug delivery,biosensors and so on.ECP as scaffolds might find applications in regulating functions and regenerating of neuron,brain cells,cardiac stem cells and orientation induced tissue regeneration.Electric stimulation was shown to affect cell prolification and differentiation.Recent progresses in conductive polypyrrole and polyaniline in biomedical field are reviewed in this paper.Some potentially rewarding research directions are suggested.关键词：Conductive polymer;Stem cell differentiation;Biosensor;Controlled release;Tissue engineering
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发布时间：2021-03-19 - 摘要：N-(3-Trimethoxysilylpropyl)-4-azido-2,3,5,6-tetrafluorobenzamide(PFPA-silane) was used to modify zinc oxide(ZnO) nanoparticles.Then,the modified ZnO particles were grafted on silicone chains by PFPA-silane.There are two different reactive groups in PFPA-silane molecules,one reacts with hydroxyl on the surface of ZnO and the other one reacts with silicone chains by grafting reaction.Group variation during reaction was characterized by infrared spectroscopy(IR),and improvement of transparency of the composite after grafting reaction was recorded with ultraviolet-visible spectroscopy(UV-Vis).Change of refractive index was recorded with an Abbe refractometer.The influence of grafting reaction on transparency of the composite is analyzed with relationship between refractive index and light transmittance of composites.It can be concluded that refractive index of the nanocomposite is changed and the refractive index mismatch between ZnO nanoparticles and silicone matrix is reduced through grafting reaction,which benefits to decrease light scattering of ZnO nanoparticles and increase transparency of the composite.The maximal increase amount of light transmittance is 50% in this experiment.The result shows that the match between inorganic fillers and polymer matrix in refractive index can be adjusted by grafting reaction of coupling agent to polymer.The chemical grafting process is useful in preparation of high transparency inorganics-polymer nanocomposites.关键词：Nanocomposite;Zinc oxide modification;Silicone;Optical property;LED packing adhesive
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发布时间：2021-03-19 - 摘要：The conductive polyaniline(PANI) was synthesized by microemulsion polymerization in the presence of magnetic field.The effects of the magnetic field and preparation conditions such as the oxidant concentration and the polymerization time on the electrochemical properties of PANI were discussed by cyclic voltammetry(CV) using the carbon paper loaded with PANI as working electrode,and the reliability of CV characterization result was proved by the analysis of the FTIR spectra(FTIR),X-ray diffraction(XRD) and four-probe conductivity measurements.The experimental results showed that compared with the PANI synthesized in the absence of a magnetic field,the PANI synthesized in the presence of magnetic field exhibited significant improvement in the crystalline degree and the conductivity properties.FTIR results indicated that the interaction force between molecules reduced,the delocalization of molecular chain increased,and the main characteristic peaks of the PANI prepared in the presence of magnetic field had the trend of moving to lowfrequency due to the orientation effect of magnetic field,but the influence of magnetization on the basic structural units of PANI was not observed.The results indicate that electrochemical behavior of the PANI synthesized by microemulsion polymerization can be real-time characterized efficiently by using the carbon paper loaded with PANI as working electrode.关键词：Polyaniline;Magnetic field;Carbon paper;Electrochemistry;Microemulsion
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发布时间：2021-03-19 - 摘要：Considering the difference of shape and dipole of side groups,the modified formulas of mean-square dipole moment and mean-square radius of gyration of the poly(alkyl acrylate) s chains were deduced by the conformational-configurational statistic theory and the generator matrix method,and they were used to investigate the conformational dependent properties of ploy(methyl acrylate)(PMA) and ploy(ethyl methacrylate)(PEMA).It is found that the characteristic ratios of mean-square dipole moment of atactic PMA4(4-state PMA) and PEMA are respectively 0.63 and 0.66,and their temperature coefficients are-0.66 × 10-3 K-1 and 1.72 × 10-3 K-1 respectively.The characteristic ratios of mean-square radius of gyration of atactic PMA4 and PEMA are 1.73 and 1.43 respectively,and their temperature coefficients are-1.05 × 10-3 K-1 and-1.28 × 10-3 K-1 respectively.The obtained results are in agreement with the experiment data.Moreover,the differences of ratios between PMA and PEMA from the change of the chain tacticity and the orientation of ester group dipole are obvious.Especially for the short chains of PMA4,there are maxima of both the dipole moment and its temperature coefficient in the syndiotactic configuration.The results display that the effect of side groups on the conformational properties of poly(alkyl acrylate) s can not be neglected.关键词：Ploy(methyl acrylate);Ploy(ethyl methacrylate);Side group;Mean-square dipole moment;Mean-square radius of gyration
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发布时间：2021-03-19 - 摘要：Amino-acid-doped polypyrroles obtained by electrochemical polymerization of pyrrole in various natural α-amino acid aqueous solutions under the nitrogen atmosphere have been studied in this paper.The experiments show that the oxidation potential is relatively low and the polymerization rate is relatively high in acidic amino acid solutions,but the electrochemical polymerization barely occurs in alkaline solutions.In the electrolytic polymerization process,the amino acids act both as supporting electrolytes,and as dopant ions doped into the polymer,which can be proved by Raman,FTIR,and UV-Vis spectra.The electronic conductivity of polypyrrole is measured in the range of 0.3 and 1.0 S /cm,and the conductivity of the products obtained in strong amino acid is obviously higher than that obtained in weak amino acid.The polymers exhibit good electrochemical activity and stability,the cyclic voltammograms of these polymers have a pair of oxidationreduction peaks between-0.5 V and 0.5 V,and their shape and trait of the polymers can stay stable after 100 electrochemical cycles.Different amino acids have different effects on the shape of the polypyrrole,polypyrrole with nano-fiber structure forms in some of the amino acid solutions due to the soft template effect,which can be seen from the SEM and TEM images.关键词：Natural α-amino acid;Electrochemical polymerization;Polypyrrole;Nano-fiber
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发布时间：2021-03-19 - 摘要：Silk fibroin(SF) was used to enhance the biocompatibility of poly(3-hydroxybutyrate-co-3-hydroxylhexnoate)(PHBHHx) porous scaffold through surface-coating.The decrease in the water contact angle from 90° to 51° and the increase in the surface free energy from 37.9 mJ /m2to 57.4 mJ /m2on the basis of comparison of SF modified PHBHHx films with SF un-modified ones,respectively,demonstrated that SF was successfully anchored on the surface of PHBHHx,enhancing the PHBHHx hydrophilicity.In order to verify the influence of the modification on the cells growth,the human umbilical vein endothelial cells(HUVECs) were seeded on the SF /PHBHHx scaffolds with un-modified PHBHHx scaffolds as control.MTT assay quantitatively demonstrated that HUVECs adhered faster and proliferated better on the SF /PHBHHx porous scaffolds than on the un-modified PHBHHx scaffolds at day 3,5 and 7.The cell morphologies observed by SEM at day 5 indicated that HUVECs formed continuous cell monolayer on the SF /PHBHHx scaffolds,while they did not on the un-modified PHBHHx scaffolds.Also,the higher collagen content on the modified scaffolds demonstrated that more extracellular matrices(ECM) were secreted by HUVECs similar to the environment of the cell growing in vivo.Therefore,the SF-modified PHBHHx is potential to be applied into the cardiovascular tissue engineering.关键词：Silk fibroin(SF);Poly(3-hydruxybutyrate-co-3-hydroyhexanoate)(PHBHHx);Human umbilical vein endothelial cells(HUVECs);Biocompatibility
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发布时间：2021-03-19 - 摘要：The copolymers of 2,2,2-trifluoroethyl methylacrylate(TFEMA) and styrene(St) were synthesized using reversible addition-fragmentation chain transfer(RAFT) polymerization in 1,4-dioxane solution,using S-1-dodecyl-S′-(α-methyl-α′-acetic acid)trithiocarbonate as the RAFT agent and 2,2′-azobisisobutyronitrile(AIBN) as initiator.The RAFT polymerization kinetics under different reaction conditions was discussed in detail.The molecular weight and chemical structure of P(TFEMA-co-St) were characterized by GPC and FTIR,respectively.The surface property and micro-topography of P(TFEMA-co-St) films were measured by contact angle method and AFM.The relatively suitable polymerization conditions were that the ratio value of [TFEMA]/[St]/[RAFT]/[AIBN]was 200∶200 ∶2∶1,and the polymerization temperature was 75℃.The results of copolymerization kinetics showed that the copolymerization was"living" and controllable.The activation energy of this polymerization was 36.49 kJ /mol.Plots of Mn versus conversion were linear.PDI of P(St-co-TFEMA) was between 1.2 and 1.4.FTIR and 1H-NMR results proved that P(TFEMA-co-St) were obtained,and that the copolymer chain showed a gradient-chain-structure character.The P(TFEMA-co-St) films had high water contact angles and relatively low surface energy,showing fluoropolymer’s characters.The micro-phase separation structure was observed in P(TFEMA-co-St) films.关键词：Reversible addition-fragmentation chain transfer polymerization;Fluorinated copolymer;Preparation
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发布时间：2021-03-19 - 摘要：In order to investigate the interfacial interaction in nano-CaCO3 /compatibilizer /polypropylene composites,three kinds of compatibilizers,polypropylene grafted with maleic anhydride(PP-g-MAH),ethylene-octene copolymer grafted with maleic anhydride(POE-g-MAH) and ethylene-vinyl acetate copolymer grafted with maleic anhydride(EVA-g-MAH) with the same polar groups(MAH) but different backbones were used as compatibilizers.Nano-CaCO3 filled polypropylenes(PP /CC) modified by PP-g-MAH,POE-g-MAH and EVA-g-MAH were prepared by on a twin-screw extruder.In the compatibilized composites,the MAH polar groups of compatibilizers associated with the surface of nano-CaCO3 particles by polarity-polarity interaction,resulting in the formation of the core-shell structure in the composites and two interfaces were obtained: PP /compatibilizer interface and compatibilizer /CC interface.The effect of PP /compatibilizer and CC /compatibilizer interfaces on crystalline morphology,crystallization and melting behavior as well as mechanical properties of PP /CC was investigated by DSC,DMA,POM and WXRD.It was observed that the interfacial interaction between PP and CC in the PP /CC composites increased the crystallization temperature due to the heterogeneous nucleation of nano-CaCO3 particles,tensile modulus and impact strength of PP.In the compatibilized composites,the interfacial interaction between CC and compatibilizer further increased the crystallization temperature of PP.The chemical reaction between polar groups(MAH) of compatibilizer and nano-CaCO3 particles in this interface may lead to the formation of carboxylate salts with more heterogeneous nucleation.The carboxylate salts acted as a more effective nucleating agent further increases the crystallization temperature and crystallization rate of PP and induces the formation of β-crystal of PP.However,the heterogeneous nucleation of carboxylate salts was dependent on the interfacial interaction of PP /compatibilizer interface.The high compatibilization between PP and PP-g-MAH was favor to increase the heterogonous nucleation of carboxylate salts and tensile property of PP composites,but decrease the impact strength of PP / CC.The partial compatibility between PP and POE-g-MAH had little influence on the heterogonous nucleation of carboxylate salts and tensile property,but significantly increased the impact strength of PP /CC.However,poor compatibilization between PP and EVA-g-MAH retarded the heterogeneous nucleation of carboxylate salts and decreased the impact strength of PP /CC.关键词：Polypropylene;Nano-CaCO3;Interfacial interaction;Crystallization;Mechanical property
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发布时间：2021-03-19 - 摘要：Amino-functionalized polystyrene nanoparticles were prepared by a facile approach.First,an amino functionalized monomer N-(3-aminopropyl)-p-vinylbenzylimine(CVPD) was synthesized by the displacement reaction of 4-vinylbenzy chloride and 1,3-propane diamine between dichloromethane.Then the nano-latex of styrene and N-(3-aminopropyl)-p-vinylbenzylimine copolymer were synthesized by UV-induced emulsion polymerization with water-soluble 4-(2-hydroxyethoxy) phenyl-(2-hydroxy-2-propyl) ketone(Irgacure 2959) as the photo-initiator and cetyltrimethylammonium bromides(CTAB) as the surfactant.The surfactant amount is only 0.1 wt% ～ 0.8 wt% of the total system,much lower than that of micoemulsion polymerization system which is generally used to synthesize nanoparticles.The diameter and diameter distribution of the P(St-co-CVPD) nanoparticles were characterized by transmission electron microscopy(TEM) and dynamic light scattering(DLS).The amino groups of the copolymer were evident from Fourier transform infrared spectroscopy(FTIR) and nuclear magnetic resonance(NMR),and the quantity of the amino groups was calculated by ninhydrin reaction.The effects of St /CVPD ratios,initiator concentrations,surfactant concentrations and UV light intensity on the polymerization system were investigated,respectively.The results show that amino-functionalized polystyrene particles with diameters of 30 ～ 600 nm,and amino group contents of 1.2 × 10-5 ～ 1.6 × 10-4 mol /g could be conveniently prepared by this method.The polymerization rate of this emulsion polymerization system is fast,and the monomer conversion can reach 80% within 60 min.The amino group content can be controlled by varying St /CVPD ratios.The particle size can be tuned by changing St /CVPD ratios,initiator concentrations,surfactant concentrations and UV light intensity.关键词：Emulsion;Amino;Nanoparticles;UV-induced polymerization
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发布时间：2021-03-19 - 摘要：The thermal properties of polymer light-emitting diode(PLED) was simulated with the light intensity of 1000 cd /m2 by using the thermal structure element in ANSYS finite element analysis software.Temperature distribution,thermal flow distribution and thermal gradient distribution were obtained,the simulation results show that the maximum temperature is in 9,9-dioctylfluorene-co-2,1,3-benzothiadiazole(PFO-BT) emitting layer of the PLED device,with temperature of 45.968℃,the minimum temperature is at the end of the quartz glass substrate,about 45.95℃;the total thermal resistance is 1305℃ /W,but the thermal resistance between polymer light-emitting layer and the end of the quartz glass substrate is only 1℃ /W.The thermal properties of PLED devices according to different input powers,substrate materials and substrate thickness were compared.The simulation results indicates that the maximum temperature TH and the device input power P show a good linear relationship;the highest temperature of the PLED device changes slightly with changing quartz glass substrate to borosilicate glass substrate,the cathode side is the main route for heat dissipation;when the substrate thickness increases continuously,the maximum temperature TH increases at the same time,however the minimum temperature TL of PLED device decreases,the total thermal resistance of the PLED device is essentially the same,the thermal resistance between light-emitting layer and the end of quartz glass substrate rises linearly.These results provide a basis for the optimization of PLED devices.
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发布时间：2021-03-19 - 摘要：Polyacrylonitrile(PAN) /polyaniline(PANI) composite nanofibers with diameter about 500 nm were successfully prepared by electrospinning a precursor mixture of PAN and aniline(ANI),followed by slow oxidative polymerization of ANI with ammonium persulfate(APS) in aqueous solutions.Morphology and structure of the resulting PAN /PANI nanofibers were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD) and laser Raman spectroscopy.The factors influencing the morphology,size and uniformity of the composite nanofibers as well as the impact of the content of PANI on the electrical conductivity of the composite nanofibers were discussed,respectively.The results demonstrated that the PAN concentration,content of ANI added and applied electric voltage were the main factors which may influence the properties of the composite nanofibers.Moreover,PANI was nanodispered in the PAN matrix.The PAN /PANI composite nanofibers possessed good electrical conductivity,and the electrical conductivity could reach 10-2 S /cm,when the PANI content was over 18%.关键词：Electrospinning;Polyaniline;Polyacrylonitrile
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发布时间：2021-03-19
Reviews
- 摘要：A solvent mixing method has been developed to enhance the field-effect mobility of poly(3-hexylthiophene)(P3HT),in which a poor-solvent,i.e.dioxane,was added into P3HT chloroform solutions.UV-Vis absorption spectra,grazing-incidence X-ray diffraction and atom force microscope reveal that the P3HT films obtained from pure chloroform solution have poor crystallinity and the molecules in crystal domains adopt a"plane-on"mode.However,the films obtained from mixing solvent show significant increase in crystallinity and change of molecule orientation to an"edge-on"mode.The reason for these improvements can be ascribed to the formation of ordered P3HT aggregates upon the addition of poor solvent,which can promote the crystallization of P3HT molecules and neutralize the adverse impact caused by the fast evaporation of low boiling point solvent.Therefore,when the concentration of dioxane is 10 vol%,the filed-effect mobility reaches the highest value 1.7 × 10-2 cm2V-1 s-1,while the mobility of the P3HT films obtained from pure chloroform is 3.1 × 10-4 cm2 V-1 s-1.The filed-effect mobility increased by a factor of 50.This method is a simple procedure for the fabrication of ordered aggregated P3HT films and can be applied to a wide range of commercial applications without post-treatment.关键词：Organic thin-film transistor;Poly(3-hexylthiophene);Field effect mobility;Mixed solvent
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发布时间：2021-03-19 - 摘要：This paper aimed to describe a bioactive polymer biointerface for endothelial cells specifically recognition.In particular,biomembrane mimetic polymers with a phospholipid group were designed.A phospholipid polymer-poly[2-methacryloyloxyethyl phosphorylcholine(MPC)-co-n-stearyl methacrylate(SMA)-co-p-nitrophenyloxycarbonyl poly(ethylene glycol) methacrylate(MEONP)](PMSN) was synthesized using AIBN as an initiator and coated on substrate(PET) by solvent evaporation.MPC unit could reduce nonspecific adsorption such as platelet,protein and cells.MEONP unit contains active ester groups on the side chains for immobilization of antibody or peptide sch as REDV.The peptide sequence Arg-Glu-Asp-Val(REDV) was known to bind preferentially to endothelial cells.As a result,MEONP units could conjugate REDV and enhance the specific endothelial cells adsorption.HNMR,UV and FTIR spectrum were used to characterize the composition of polymer and immobilization of REDV peptide plasma recaleification time(PRT) was detected to show the hemocompatibility of polymer coating.Cell adhesion and proliferation experiments showed excellent specific recognition of endothelia cells on biomimetic coatings.Many endothelial cells were observed and the number of endothelial cells adhering to the PMSN polymer surfaces increased but cell adhesion was markedly reduced on poly(MPC-co-SMA)(PMS).For smooth muscle cells(SMC),many adherent cells were observed and well spread on PET but little on PMS and PMSN by the reason of nonspecific adhesion of MPC for smooth muscle cells.In conclusion,MEONP units and MPC units of PMSN are important for supporting ECs and for reducing SMCs.The PMSN-coated surface was suitable for biorecognition and preservation of cell function.The biomembrane mimetic phospholipid polymer produced an excellent prospect in cardiovascular stent coating.关键词：Endothelial cell selectivity;Stent coating;MPC;REDV peptide
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发布时间：2021-03-19 - 摘要：A method was presented to prepare polyimide microspheres in non-aqueous inverse emulsion.The non-aqueous inverse emulsion was compounded with N,N-dimethyl formamide /(pluronic-F127,dodecylbenzenesulf) /liquid paraffin,in which the poly(amic acid) was synthesized with monomers of pyromellitic dianhydride and 4,4′-diaminodiphenyl ether.Then the polyimide particles were precipitated through the chemical imidization using the acetic anhydride /pyridine mixture as dehydrating agent.Ultimately,polyimide particles were completely imidized via thermal imidization.The stability of non-aqueous inverse emulsion were investigated,and the effects of solid content and thermal imidization temperature on the morphology of polyimide microspheres were also discussed.The properties of the product were characterized with FTIR,SEM and TG /DTG.The results showed that it was favorable to form the polyimide microspheres with higher solid content and better emulsion dispersity.The non-aqueous inverse emulsion was optimal when the volume ratio of N,N-dimethyl formamide to liquid paraffin was 1 ∶ 4,the mass ratio of pluronic-F127 to dodecylbenzenesulf was 3 ∶ 2,and the content of emulsifiers was 9 wt%.In addition,the polyimide particles were well dispersive,spherical and highly thermal stable with a narrow size distribution when the solid content was 20% and the thermal imidization temperature was less than 330℃.The average particle diameter was about 10 μm.关键词：Non-aqueous inverse emulsion;Polyimide;Microspheres
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发布时间：2021-03-19
Research Bulletin
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