最新刊期
卷 ， 期 8 ， 2013
- 摘要：The effect of nucleating agent (zinc phenylphosphonate,PPZn) and its adjuvant (E61) on the crystallization morphology and capacity of poly(lactic acid) (PLA) was investigated.The crystallization morphologies of PLA are varied with the content of PPZn and E61.PPZn can effectively act as nucleus sites of PLA when the content of PPZn is 0.1 wt%,and spherical crystal of PLA is obtained.However,needle-like crystal is observed with an increase of PPZn (0.3 wt%) owing to the self-assembly of PPZn.The effect of E61 on the crystallization morphologies of PLA is further investigated when the content of PPZn is fixed at 0.3 wt%.The needle-like crystal of PLA without E61 changes to spherical crystal with low content of E61 (0.06 wt%),which may be attributed to the improvement of crystal growth mainly on the short axis but not on the long axis of PPZn.While a higher content of E61 ( 0.15 wt%) can inhibit the crystal growth of PLA,resulting in the formation of needle-like structure.In addition,the inhibition of E61 with 0.3 wt% shows more serious than that with 0.15 wt% E61.The results of DSC and rheological test demonstrate that the crystallization rate can be obviously improved by the introduction of PPZn,while the addition of E61 has little effect on that of PLA.关键词：PLA;Nucleating agent;Adjuvant;Spherical crystal;Needle-like crystal
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发布时间：2021-03-19 - 摘要：The copolymer PMT82 was synthesized by free radical polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) and trimethoxysilylpropyl methacrylate (TSMA) with the monomer ratio of 8∶2.The copolymer PMT82 was dip-coated onto glutaraldehyde-crosslinked chitosan (CS-GA) surfaces to prepare phosphorylcholine-coated CS-GA film (CS-GA-PMT82a) and then stabilized by the amine-catalyzed crosslinking reactions of the trimethoxysilane groups,obtaining the phosphorylcholine-crosslinked CS-GA surfaces (CS-GA-PMT82b).The hydrophilicity and elementary composition of the modified surfaces of were characterized by dynamic contact angle (DCA) measurements and X-ray photoelectron spectroscopy (XPS).The obvious decrease in the contact angles and the new signals for P2p,Si2p and N+(CH3)3 provided strong evidences for the successful establishment of PMT82 on the CS-GA surface.The anticoagulation property of the surfaces was estimated by platelet adhesion measurements.Compared with the chitosan films,the CS-GA-PMT82b surfaces massively reduced the platelet adhesion,indicating that the cell outer membrane mimetic structures were formed on the modified surfaces with PMT82 as the coat,which led to the significantly improved anticoagulation property of the modified surfaces of the composite material.This facile method of fabricating the stable cell outer membrane mimetic surfaces by dip-coating and catalytic crosslinking may have potential applications in the fields of anticoagulation property coatings,drug delivery,and tissue engineering.关键词：Chitosan;Cell outer membrane mimetic structures;Phosphorylcholine;Anticoagulation
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发布时间：2021-03-19
Rapid Communications
- 摘要：Azobenzene-containing liquid crystalline block copolymers represent a special category of block copolymers and functional materials.The combination of photoresponsive properties of azo polymers and hierarchical supramolecular structures of liquid crystalline block copolymers leads to their unique characteristics and functions.Research in this field has generated a number of new block copolymers and recorded some newly discovered properties of the copolymers.In this review,a few examples were chosen to discuss the recent developments in this area with emphasis on the photoinduced morphological changes and holographic properties of this type of polymers and materials.关键词：Azo polymer;Block copolymer;Liquid crystal;Photoresponsive properties;Holography
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发布时间：2021-03-19
Reviews
- 摘要：In this article,our main goal is to establish a novel functional poly(amidoamine) dendrimer with cyclodextrin core for further application in the complex drugs delivery system.Therefore,the different generation poly(amidoamine) dendrimers with a core of cyclodextrin (CP) were synthesized via the divergent approach by using (aminoethyl)amino--cyclodextrin (EDA--CD) and methyl acrylate as the starting materials.Then the CP modified by salicylaldehyde (CPS) having different generations was obtained by co molecular interaction of various dendrimers with bovine serum albumin (BSA) was a investigated by ndensation reaction.All of them were characterized by 1H-NMR,13C-NMR and IR.The molecular interaction between various dendrimers with bovine serum albumin(BSA) was investigated by fluorescence in buffer solution (pH=7.4).The results show that BSA fluorescence was strongly quenched by the two types of dendrimers.As shown by Ksv values,the quenching mechanism was a static quenching one,and the data increase with the increases of generation.In addition,the two types of dendrimers (CP and CPS) possess higher interaction ability than the corresponding dendrimers with an ethylenediamine core,which indicates that the dentrimers with a core of cyclodextrin and end groups modified by salicylaldehyde can enhance the ability of interaction between dendrimers and BSA.关键词：Poly(amidoamine) dendrimer;-Cyclodextrin;Bovine serum albumins;Fluorescence quenching
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发布时间：2021-03-19 - 摘要：-Triethoxysilylpropylamine (APTES) was grafted onto the surface of attapulgite rod crystals to get the modified particles AT-APTES,and then a redox initiating system was constructed with the primary amino groups on the surface of AT-APTES particles and the ammonium persulphate in the solution,the surface-initiated graft polymerization of methyl methacrylate was realized and the hybrid particles AT-g-PMMA with a high grafting degree of 29.4% were obtained at last.The hybrid particles were characterised by FTIR,Raman,TEM and TGA.The results showed that APTES was grafted onto the surface of attapulgite rod crystals and PMMA was grafted from the surface of AT-APTES particles successfully.The effects of some factors on the grafting polymerization of MMA were investigated mainly.The experimental results show that the optimal temperatures is of the surface-initiated graft polymerization is 65 ℃ and the decrease of grafting degree at higher temperatures is due to the heat decomposition of ammonium persulphate.The quantity of APS which accounted for 1 wt% of the monomer mass was chosen as the most reasonable amount,and the appropriate monomer concentration 6 wt% of the water mass.In addition,the grafted polymer layer would restrain subsequent grafting polymerization and polymerization location would transfer from the surface of attapulgite to half polymer micelle with higher temperature and excessive monomer or ammonium persulphate.关键词：Attapulgite;Methyl methacrylate;Redox initiating system;Surface-initiated graft polymerization;Grafting degree
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发布时间：2021-03-19 - 摘要：A structured nanoparticle support was prepared by using diol as precipitant to recrystallize nano-sized MgCl2 on the surface of SiO2.TiCl4 was immobilized on the surface of the resulting structured nanoparticle support,forming structured nanoparticle Ziegler-Natta cataylst.The resulting catalyst was used to catalyze the slurry-phase polymerization of ethylene.Polyethylene produced was characterized with scanning electron microscopy (SEM),differential scanning calorimetry (DSC) and particle size analysis.In order to obtain the proper catalyst,the influence of diol/MgCl2 ratio on support morphology,catalysis features of structured nanoparticle catalyst and characteristics of products were investigated.Results showed that the structured nanoparticle Ziegler-Natta catalyst was an excellent catalyst for producing ultra high molecular weight polyethylene (UHMWPE) because of its special particle morphology.Polymerization activity and molecular weight of products were both sensitive to the temperature.At the optimum temperature,polymerization activity could reach as high as 1261 kg PE(molTi)-1h-110-5Pa-1 and molecular weight of product could reach as high as 5.87106.UHMWPE produced with structured nanoparticle Ziegler-Natta catalyst had a high crystallinity degree which could reach 49.5%.It also performed a uniform spherical morphology with an average particle size of 68~69 m and moreover the distribution of particle size was very narrow.These were all beneficial to the processing of UHMWPE.关键词：Ultra high molecular weight polyethylene;Structured nanoparticle catalyst;Diol recrystallization;Ziegler-Natta catalyst
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发布时间：2021-03-19 - 摘要：The hydrophobically associating hydrogels,namely HA gels and SHA gels,were prepared by free radical copolymerization of acrylamide (AM) and sodium 9 or 10-acrylamidostearic acid (NaAAS) in pure water and in aqueous solution of sodium dodecyl sulphate (SDS),respectively,without any chemical crosslinkers.The mechanical properties of HA gels and SHA gels were systematic investigated by one-way tensile experiments,and the results confirmed the high toughness of the as-obtained hydrogels.Further more,by adjusting the AM and NaAAS contents,the SHA gels could exhibit ultrahigh toughness compared to the HA gels without SDS.The swelling behaviors of HA and SHA gels in aqueous solutions and in 0.1 mol/L NaCl were studied,respectively.The HA gels were not soluble in water,and almost no weight loss was detected during the purification and swelling processes.However,SDS could escape from the hydrogel networks into water,leading to the unique process of swelling-deswelling-swelling equilibrium; in brine,both of the HA gel and SHA gel show the swelling curves just like those of chemical cross-linked hydrogels because the hydrophobically association strength of the physical cross-linked units are strengthened by introduction of NaCl.Moreover,the HA gels couldnt heal themselves at room temperature.However,the SHA gels exhibited well self-healing ability,and the self-healing effect could be improved by adjusting the SDS and polymer contents.关键词：Hydrogel;Hydrophobic association;Mechanical strength;Swelling behavior;Self-healing
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发布时间：2021-03-19 - 摘要：In order to meet the requirements of proton exchange membranes in direct methanol fuel cells (DMFCs),sulfonated poly(aryl ether ketone) bearing pendant sulfonic acid groups/PVA (S-SPAEK/PVA) crosslinked composite membranes with different contents of PVA are prepared by solution blend method.S-SPAEK/PVA crosslinked composite membranes are obtained by a heating reaction at 120 ℃.FTIR spectra show that crosslinked structure is formed due to the bonds of COS between the sulfonic acid groups on S-SPAEK and hydroxyl groups on PVA.The swelling ratio both at length and thickness,water retention capacity and methanol permeability of S-SPAEK/PVA cross-linked membranes are improved due to the introduction of PVA.The water diffusion coefficient of the S-SPAEK/PVA (85/15) cross-linked membrane reaches 2.910-9 cm2/s which is lower than that of pure S-SPAEK membrane (3.110-8 cm2/s).The methanol diffusion coefficient values of S-SPAEK/PVA (85/15) cross-linked membranes at 25 ℃ and 60 ℃ reach 2.610-7cm2/s and 3.910-7 cm2/s,respectively,which are obviously lower than 8.110-7 cm2/s and 14.510-7 cm2/s of pure S-SPAEK membranes under the same test conditions.It can be obviously seen that the methanol diffusion coefficient of S-SPAEK/PVA cross-linked membranes decreases with increasing the content of PVA.Although the proton conductivities of S-SPAEK/PVA (85/15) cross-linked membranes are decreased,they still reach 0.055 S/cm at 25 ℃ and 0.083 S/cm at 80 ℃,respectively.All the results indicate that the S-SPAEK/PVA (85/15) crosslinked composite membranes are promising as proton exchange membranes for DMFCs applications.关键词：Sulfonated poly(aryl ether ketone);PVA;Crosslinked composite membranes
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发布时间：2021-03-19 - 摘要：A series of equimolar blends of poly(L-lactic acid)/poly(D-lactic acid) (PLLA/PDLA) were prepared by melt mixing and the blends were investigated by means of differential scanning calorimetry (DSC),nuclear magnetic resonance (13C-NMR),wide angle X-ray diffraction (WAXD),etc.It was found that when the blending temperature was 210 ℃, the stereocomplex (sc) formed from equimolar PLLA/PDLA blends exhibited a high melting temperature at 229 ℃ and showed 98.1% crystallinity degree.As for the sample after isothermal annealing up to 120 ℃,the Vicat softening temperature approached to 126.4 ℃.It was indicated that double melting endotherms were characteristic for the sc crystals in the DSC thermograms,where formation of the stereoblock (sb) occured at high processing temperatures.The high-temperature-side (230 ℃) endotherm and the low-temperature-side (210 ℃) endotherm resulted from the melting of sc and sb crystals respectively.As the blending temperature increased,the high-temperature-side endotherm was reduced and the low-temperature-side endotherm was emphasized.The relative amounts and crystallinity degree of sc crystals decreased significantly with the increase of blending temperature.The sc-PLA had good processing stability.The melting temperature of sc crystals stayed constantly after second blending.Moreover,the relative amounts of sc crystals increased slightly.The PLLA/PDLA blends composed of networks of sc might be applicable to the heat-resistant materials,and this paper provided a new method of improving thermal stability and processing property of PLA.关键词：PLA;Stereocomplex;Stereoblock;Melting blending
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发布时间：2021-03-19 - 摘要：Aqueous copolymer dispersion of acrylamide (AM) and 2-methylacryloylxyethyl trimethyl ammonium chloride (DMC) was synthesized through dispersion polymerization in aqueous solution of ammonium sulfate and a modicum of sodium chloride or lithium sulfate,using poly(acryloylxyethyl trimethyl ammonium chloride) (PDAC) as the stabilizer and the combination of 2,2'-azobis(N,N'-dimethyleneisobutyramidine) dihydro chloride (VA-044) and potassium persulfate (KPS)/formaldehyde sodium bisulfite (SFS) as the initiator.The resultant product was characterized using Fourier transform infrared (FTIR) spectroscopy and H nuclear magnetic resonance (1H-NMR) spectroscopy to evaluate the chemical composition and structure.The results showed that DMC participated in the copolymerization process with AM in accordance with the feeding ratio.Copolymerization progress was monitored with optical microscopy to reveal the particle formation mechanism.Polydisperse spherical particles were formed in the system.The effects of initiator type and concentration,inorganic salts concentration,stabilizer concentration as well as AM/DMC molar feed ratio on the polymerization conversion,the dispersion viscosity,the copolymer molecular weight were systematically studied.The optimum reaction conditions for preparing stable dispersion with good fluidity were concentrations of 28%~32% of ammonium sulfate,1% of sodium chloride or lithium sulfate and 0.5%~1.5% of the stabilizer.关键词：Cationic polyacrylamide;Aqueous dispersion;Dispersion polymerization;Sludge dewatering
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发布时间：2021-03-19 - 摘要：Oleic acid capped Li3PO4 nanocrystals were synthesized in high boiling coordinating solvent.After modifying Li3PO4 nanocrystals with amphiphilic polymer poly(ethylene glycol)-oleate (PEG-oleate),Li3PO4/PMMA nanocomposites were obtained by means of in situ photopolymerization method.The X-ray diffraction (XRD) pattern indicates a pure orthorhombic structure of Li3PO4(JCPDS:25-1030) with a space group of Pmn 21(31).The boarding peaks suggest that the size of Li3PO4 nanocrystals is about 10 nm,which is also demonstrated by TEM.The XRD pattern of the nanocomposites shows obvious peaks of Li3PO4,which confirm the existence of Li3PO4 nanocrystals in PMMA matrix.The TEM analysis of ultramicrotome cut of composite demonstrates that Li3PO4 nanocrystals are dispersed in the PMMA matrix with about 50 nm agglomerations,which contributes to the decrease of transparence of the nanocomposites.The FTIR spectroscopy of as synthesized Li3PO4 nanocrystals shows absorbance bands at 2920 and 2850 cm-1,which are attributed to CH symmetric and asymmetric stretches respectively.The weak absorption at 2955 cm-1results from the asymmetric stretching of the terminal CH3 group of the alkyl chain.The spectrum indicates the presence of an adsorbed carboxylate group with symmetric and asymmetric modes around 1634 and 1466 cm-1,respectively.The FTIR spectroscopy indicates the Li3PO4 nanocrystals are well capped by oleic acid.The UV-Vis transmission spectra show the nanocomposites still maintain the transmittance of 75% even with 14.6 wt% Li3PO4 content.The thermogravimetric analysis (TGA) reveals the thermal stabilities of nanocomposites are significantly improved after incorporating the Li3PO4,as evidenced by a retardation of degradation initiation of 95 K.The improvement in the thermal property of Li3PO4/PMMA nanocomposites could be attributed to the increase of surface area and the interaction between the surface of Li3PO4 nanocrystals and the polymer chains.All the results indicate that the as prepared Li3PO4/PMMA nanocomposites are promising materials for thermal neutron detection.关键词：Li3PO4 nanocrystals;PMMA;In situ polymerization;Nanocomposites;Thermal neutron detection
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发布时间：2021-03-19 - 摘要：The high-efficient assembly of plasmid DNA by polymers has become important for successful delivery of gene materials into the target cells.In this research,four polymers were synthesized by coupling phenylalanine (Phe) and tryptophan (Trp) to poly(amidoamine) dendrimers of generation 2(G2) and 4(G4),respectively,so as to mimic the function of viral proteins.Then,the assembly of the plasmid DNA and polymeric vectors was investigated with agarose gel electrophoresis,ethidium bromide displacement assay and dynamic light scattering.The results indicated that Phe-G4 and Trp-G4 could self-assembly with the plasmid DNA to form more compact nano-sized particles with hydrodynamic radii of ca. 40 nm.It was driven by electrostatic interaction and structural rearrangement.Moreover,Phe-G4 and Trp-G4 exhibited high cell viability in COS-7 cell lines,meaning low cell toxicity of the polymeric vectors.The plasmid pEGFP-CL was transfected successfully in vitro by both Phe-G4 and Trp-G4 and the transfection efficiency of Phe-G4/plasmid DNA polyplexs was over four-times higher than that of liposome-mediated delivery method.In concern with these results,it is confirmed that Phe-G4 is a potential candidate as a high-efficient gene delivery system.关键词：Poly(amidoamine) dendrimers;Gene delivery;Plasmid assembly;Light Scattering;Isothermal titration calorimetry;Transfection
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发布时间：2021-03-19 - 摘要：Poly(2,3-dimethylaniline)(P(2,3-DMA)) was synthesized by a rapid emulsion polymerization using ammonium peroxydisulfate and ferrous ion (APS/Fe2+) as composite oxidants.The effect of Fe2+ on the rate of polymerization of 2,3-dimethylaniline (2,3-DMA) was discussed by open circuit potential (OCP) curves,and the molar ratio of APS and Fe2+ and the amount of composite oxidant were optimized by cyclic voltammetry and Tafel curves.And the characterization results of electrochemical properties of P(2,3-DMA) were proved by contrast analysis of infrared spectroscopy (FTIR) and X-ray diffraction (XRD).The experimental results showed that main infrared absorption peaks of P(2,3-DMA) which was synthesized by the composite oxidant exhibited red-shift.The phenomenon revealed that the structure of products was relatively complete and the electron delocalization increased.The optimal properties of P(2,3-DMA) were achieved when the molar ratio of APS to Fe2+ was 10∶1,the molar ratio of APS to 2,3-DMA was 3∶1.The open-circuit potential measurements indicated that the rate of polymerization of 2,3-DMA with the aid of Fe2+ had a substantial increase.The P(2,3-DMA) with higher yield,better electrochemical and crystal properties have been prepared by composite oxidant APS/Fe2+.关键词：Poly(2,3-dimethylaniline);Emulsion polymerization;Composite oxidant;Rapid polymerization
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发布时间：2021-03-19 - 摘要：Poly(glycidylmethacrylate),(PGMA) is prepared by atom transfer radical polymerization (ATRP),while 2-bromoisobutyrate ethyl (NA) is used as the initiator.Hydrophilic comb polymer PGMA-g-EDA is prepared through the ring-opening reaction of PGMA with ethylenediamine (EDA).Nuclear magnetic resonance,infrared spectroscopy and gel permeation chromatography were used to characterize the structure and molecular weight distribution of PGMA and PGMA-g-EDA.The comb polymer PGMA-g-EDA modified quantum dots (QDs) by ligand exchange to prepare water-soluble quantum dots.The quantum dots has good stability in water,UV-Visible spectroscopy and fluorescence emission spectra were used to study the optical properties of quantum dots,indicating that the QDs arent destroyed and have the same optical properties of the unmodified QDs.Transmission electron microscopy and dynamic light scattering color test show that the water-soluble quantum dots are monodisperse,uniform,and have small size,no significant surface deterioration or aggregation and solubility in water.The stability of QDs is studied against photo-oxidation,H2O2-oxidation and acid etching,the result implies that the QDs are very stable in water,and no deterioration or aggregation of the quantum dots occurrs in water.Whats more,the way of synthesis of PGMA and PGMA-g-EDA and modification of QDs are extremely convenient.关键词：Glycidylmethacrylate;Atom transfer radical polymerization;Ring-opening reaction;Quantum dots;Water-soluble
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发布时间：2021-03-19 - 摘要：By adopting sulfydryl-benzoyl peroxide redox initiating system,the surface-initiated graft-polymerization of glycidyl methacrylate (GMA) on micron-sized silica gel particles was first realized,obtaining grafted particles PGMA/SiO2 with a high grafting degree,and then the ring-opening reaction of the epoxy groups of the grafting macromolecule PGMA with 5-aminosalicylic acid (ASA) was carried out,leading to bonding salicylic acid (SA) onto the side chains of the grafting macromolecule PGMA and resulting in the functional grafting particles SA-PGMA/SiO2.The chemical structure and surface-electrical property of SA-PGMA/SiO2 particles were characterized.The interaction between the functional grafting particles SA-PGMA/SiO2 and theophylline molecule as the substitute of caffeine was examined in depth.The investigation result shows that there exist strong secondary bond forces between the functional grafting particles SA-PGMA/SiO2 and theophylline molecules,including electrostatic interaction and hydrogen bonding.On that basis,the molecular imprinting towards the grafted SA-PGMA was performed with theophylline as template molecule and ethylene glycol diglycidyl ether (EGDE) as crosslinking agent by using the novel surface-molecular imprinting technique established by our research group,and the theophylline molecule-imprinted material MIP-SAP/SiO2 was prepared.With diprophylline and matrine as two contrast compounds,both static and dynamic methods were adopted to investigate the binding properties and molecule recognition character of MIP-SAP/SiO2 for theophylline molecule.The experiment results show that MIP-SAP/SiO2 have specific recognition selectivity and excellent binding affinity for theophylline.Relative to the contrast substance,diprophylline,the coefficient of recognition selectivity of the imprinted material MIP-SAP/SiO2 for theophylline is equal to 7.72,displaying excellent recognition selectivity for the template molecule.关键词：Poly(glycidyl methacrylate);Silica gel;Molecular surface-Imprinting;Caffeine substitute;Molecule recognition
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发布时间：2021-03-19 - 摘要：The dynamics of different helical protein-like chains translocating through a channel has been studied by Dynamical Monte Carlo (DMC) simulation.Translocation time,translocation probability,the number of monomers inside channel nin, shape factor and mean-square displacement of center of mass g are discussed.It is shown translocation time of protein-like chain with small helical energy is short,and changes little.However,for chains of large helical energy,the translocation time quickly increases when h becomes stronger.The results show that the translocation probability is smaller as the electric field becomes stronger.For different helical chains the translocation probability of h=0 is the largest,about 80%,smaller than that of SAW chain.But it suddently drops for h=-0.5.Then the translocation probability increases again as the helical energy becomes stronger.Furthermore,the curve of nin shows the translocation process of SAW chains is more steady than that of protein-like chains.The maximum value in the curves of suggests there exists the loosest conformation during translocation.Another discussion about the mean-square displacement of center of mass g shows that g of h=0 changes faster than others.It shows diffusion of h=0 is the fastest.It is also observed that the value g of h=-3.0 changes faster than that of h=-1.5.The discussion of shape factor and mean-sqare displacement can explain the different properties of different helical protein-like chains.All these studies will be useful for the complex translocation behaviors of macromolecules.关键词：Dynamical Monte Carlo (DMC);Protein-like chain;Helical structure
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发布时间：2021-03-19 - 摘要：In order to obtain polymer electrolytes with high ionic conductivity at room temperature,multi-arm star polymers (HBPS-PEO) containing polyoxyethylene arms of different molecular weights (PEO750,PEO1000 and PEO1900) were successfully synthesized by click chemistry of hyperbranched polystyrene with azide groups (HBPS-N3) and polyoxyethylene with an alkynyl group (ay-PEO).The structures of the obtained star polymers were characterized by ATR-FTIR,1H-NMR,GPC,respectively.Ionic conductivities of polymer electrolytes composed of HBPS-PEO and lithium trifluoromethane-sulfonimide (LiTFSI) were investigated via electrochemical impedance spectroscopy.The influences of the arm length of the prepared star polymer,the content of lithium salt in polymer electrolyte and the structure of the polymer matrix on ionic conductivity were also studied.The results showed that star polymer electrolyte with arms of PEO1000 exhibited the highest ionic conductivity,while star polymer electrolyte with arms of PEO1900 had the lowest ionic conductivity,indicating the star polymer with shorter PEO arms possessing lower crystallinity was benefit for the transport of ions.The content of lithium salt also affected the ionic conductivity.The result suggested that ionic conductivity first increased and then decreased gradually with the change of the content of lithium salt.The maximum was achieved when n(EO)/n(Li)=40.Besides,DSC results showed that the star-shaped structure of the polymer could inhibit the formation of crystals.Lower degree of crystallinity of star polymer and star polymer electrolyte than corresponding linear PEO was observed,and higher ionic conductivity at low temperatures was found for electrolyte based on star polymer than that of corresponding linear PEO electrolyte.The conductivity of the star polymer electrolyte was 6.710-5 Scm-1 at 30 ℃,and could reach 1.210-4 Scm-1 at 40 ℃.TGA results showed that all of the prepared star polymers exhibited good thermal stability with Tonset above 360 ℃.It is concluded that star-branched structure can inhibit the formation of crystals,which facilitates the improvement of ionic conductivity at low temperatures,and proper length of PEO chains is necessary to achieve high ionic conductivity.关键词：Click reaction;Multi-arm star polymer;Polymer electrolyte;Ionic conductivity
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发布时间：2021-03-19 - 摘要：To overcome the shortcomings of pure phenolic resin,such as high brittleness and easy pulverization,the blending modification of phenolic resin with polyimide was introduced.Polyethylene glycol was also added into the phenolic/polyimide composite to investigate its influence on the composite properties.The composites were characterized by FTIR,TG and HRTEM.The peak of CO stretching vibration (1008 cm-1) becomes weaker in phenolic/polyimide composite than that in neat phenolic resin which means that hydrogen bonds form between PI and PF polymer molecules.From the HRTEM morphologies,the formation of interpenetrating networks in phenolic resin composite could be observed.The modified phenolic resin by polyimide shows obvious improvement in thermal stability,compression strength and thermal insulation properties.The chalking rate and water absorption are also reduced.However,the brittleness of the phenolic/polyimide composite still remains high.The addition of polyethylene glycol into the phenolic/polyimide composite can well resolved this problem.The brittleness of the phenolic/polyimide composite system got better while the other properties such as the compression strength,thermal stability and thermal insulation became worse.From the study we could draw a conclusion that the optimum addition quantities of polyimide and polyethylene glycol are 3% to 5% for the improvement of the overall performance of phenolic foam plastic which makes such material meet the criterion for ship standard.关键词：Polyimide;Polyethylene glycol;Phenolic foam plastic;Blending modification;Compositing process
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发布时间：2021-03-19 - 摘要：A facile method to prepare the hollow microspherical polyaniline was developed utilizing potassium hexacyanoferrate (Ⅲ) as the oxidant for polymerization of aniline in aqueous condition without any acid or alkali or organic solvent,and the doped polyaniline with electrical conductivity of 10-3 S/cm could be directly obtained with hexacyanoferrate (Ⅱ) anion surrounding imine and amine atoms in polyaniline main-chain.And this value was almost seven orders of magnitude higher than the polyaniline hollow spheres synthesized in alkaline medium.This product was then characterized by Fourier transform infrared (FTIR) spectroscopy,X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM).A systematic and careful electrochemical test was carried out to deeply investigate its potential application for lithium-oxygen battery.The experimental results show that,this low cost and easily produced material could catalyze the battery discharge reaction independently,and its first discharge capacity is almost twice as high as that for the cathode made by traditional bulk polyaniline material.After an initial degradation from 2631 to 1748 mAh/g PANI during the first 5 cycles at a current density of 0.05 mA/cm-1,its discharge capacity kept relatively stable in the next 25 cycles with only 5% loss,which may provide a new choice for fabrication of high-capacity rechargeable lithium-oxygen battery for practical application.关键词：Polyaniline;Hollow microsphere;Lithium-oxygen battery;Cathode
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发布时间：2021-03-19 - 摘要：The melts of poly(lactic acid) underwent two different treatments (naturally cooling (CN) and rapidly compressing respectively).For the first time,amorphous PLA samples have been successfully prepared by rapidly compressing (RC) process,and its isothermal cold crystallization behavior and the corresponding crystalline structure were studied by using differential scanning calorimetry (DSC),Fourier transform infrared (FTIR),and wide angle X-ray diffraction (WAXD).It was found that RC samples possessed a faster crystallization rate and higher final crystallinity than those of CN samples at all selected cold crystallization temperatures (110,115,125,130,135 and 140 ℃,respectively) according to the FTIR and WAXD data.However,there was almost no difference of the crystallize size between RC and CN samples.With the FTIR and WAXD results,it could be concluded that the crystal nucleation density was higher in RC samples.Besides,polarized FTIR results exhibited that there was no orientation of molecular chains in the raw RC samples,thus the impact of molecular orientation on crystallization behavior of RC samples could be excluded.As a result,the unique crystallization behavior of RC samples could be attributed to the higher crystal nucleation density,which was caused by local order domains formed during the rapid compression process,accelerating the crystallization rate and increasing the final crystallinity of RC samples.关键词：Amorphous polylactic acid;Rapid compression;Isothermal cold crystallization;Local order domains
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发布时间：2021-03-19 - 摘要：High molecular weight linear poly(ethylene terephthalate-co-ethylene 2,5-furandicarboxylate) (PEFT) was synthesized via direct esterification method based on terephthalic acid,2,5-furandicarboxylic acid(FDCA) and ethylene glycol.Tetrabutyl titanate was used as catalyst.Magnetic resonance spectroscopy (1H-NMR and 13C-NMR) confirmed the expected PEFT structure.The results of X-ray diffraction (XRD) displayed that the PEFT copolyesters were amorphous at original ecology.The results of differential scanning calorimeter (DSC) showed that the PEFT copolyesters had a single glass-transition temperature Tg (73.3~84.2 ℃) and Tg increased continuously with the increase of PEF content.The Tgs of PEFT copolyesters were between that of PET and PEF.The results of thermo gravimetric analysis (TGA) indicated that PEFT copolyesters had excellent thermal stability,although it was slightly lower than that of PET.The PEFT copolyesters were thermally stable up to 390 ℃.The thermal properties of PEFT copolyester were between those of PET and PEF.The results of tensile tests showed that PEFT-10,PEFT-70 and PEFT-90 copolyesters had good mechanical properties compared with PET.The results showed that FDCA could partially replace terephthalic acid to synthesis polyester.关键词：Copolyester;2,5-Furandicarboxylic acid;Terephthalic acid;Direct esterification method;Synthesis and characterization
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发布时间：2021-03-19 - 摘要：With ethanol and water mixture (H2O-EtOH) as the solvent,precipitation polymerization of trihydroxymethyl propane triacrylate (TMPTA,the crosslinker monomer) and styrene (St) was carried out using 2,2'-azobis-(isobutyronitrile) (AIBN) as the initiator.Microspheres of uniform size were obtained in most of the polymerizations done with varied TMPTA/St mass ratio and in H2O-EtOH with different water amounts.The yields of the microspheres and soluble oligomers were determined.Results indicate that both the yields increased with increased TMPTA in the monomer mixture; whereas with increased water amount in the polymerization solvent,the yield of the microspheres was promoted while that of the soluble oligomers was reduced.Number average size and size distribution of the microspheres were obtained from SEM.Hansen three dimensional solubility parameters (s,h and p) were calculated for the monomers and H2O-EtOH binary solvent,and so were the differences between their solubility parameters.Boundary limitations for the formation of the uniform microspheres were established based on the difference (p) of polar solubility parameters (p) between the solvent and the monomer mixture,and that (h) of hydrogen bonding solubility parameters (h).With three sets of p and h at (5.0,12.4),(9.2,20.1) and (6.0,10.0) (expressed as p,h),an enclosed experimental zone was set,uniform microspheres can be expected when the polymerization is conducted within the limits of this enclosed zone.关键词：Precipitation polymerization;Uniform microsphere formation;Hansen solubility parameters;Trihydroxymethyl propane triacrylate;Water-ethanol mixed solvent
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发布时间：2021-03-19 - 摘要：A new method of surface modifaction for selective endothelial cell adhesion was developed.A diblock copolymer,poly［oligo (ethylene glycol) methyl ether methacrylate］-block-poly(glycidyl methacrylate) (POEGMA-b-PGMA),was grafted on silicon wafer surface via surface-initiated atom transfer radical polymerization (SI-ATRP),and endothelial specific peptide Glycine-Arginine-Glutamic acid-Aspartic acid-Valine-Tyrosine (GREDVY) was conjugated through the epoxy groups in PGMA segments.Surfaces were characterized by water contact angle and X-ray photoelectron spectroscopy (XPS) measurements to confirm the modification reactions.Ellipsometry measurements indicated that the thickness of POEGMA layer was 26 nm after 8 h ATRP,and the subsequent ATRP of second (PGMA) block for 0.5 h resulted in further increase of 19 nm in thickness.Phase segregation of the copolymer blocks in the layer was observed by atomic force microscope (AFM).Cell interactions showed that both fibroblast and endothelial cell were prevented from adhesion and growth by surface grafting of POEGMA.On GREDVY conjugated POEGMA-b-PGMA surface,only limited amount of fibroblasts were adhered and cell growth was restricted,while endothelial cell adhesion was greatly promoted and the cells showed normal morphology.The high selectivity for endothelial cells is due to the novel copolymer spacer:the bio-inert segment (POEGMA) for cell resistance and the chemically-active segment (PGMA) for binding large amount of GREDVYs which promote endothelial cell adhesion and proliferation.关键词：Poly［oligo (ethylene glycol) methyl ether methacrylate］;Poly(glycidyl methacrylate);GREDVY;Endothelial cell;Selective adhesion
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发布时间：2021-03-19
Research Article
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