最新刊期
卷 ， 期 2 ， 2014
- 摘要：polymer materials are a class of materials of great importance for their peculiar chemical-physical properties.The basic principles of X-ray absorption fine structure (XAFS) which is promoted by synchrotron radiation,including extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) were introduced.Various XAFS methods were reviewed for applications in studies of polymers and related materials,including usual polymers,organometallic polymers,Pd-droped polymers,ionomers,carbon based materials,etc.These mentioned applications have showed the significance and advantage of XAFS in polymers and related materials field.It is confident that the promotion and growth in XAFS would bring more benefits in scientific research of polymers.关键词：Polymer materials;X-ray absorption fine structure (XAFS);Atomic structures
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发布时间：2021-03-19
Reviews
- 摘要：The performance changes of cellulose I in the ammonia environment and non-ammonia environment were studied based on molecular dynamics simulation. The end-to-end distance of one cellulose chain, the diffusion behavior of ammonia in cellulose and hydrogen bonds between cellulose and ammonia were investigated. The results indicated that the end-to-end distance of the cellulose chain in ammonia environment got longer than that in non-ammonia condition with improving the flexibility of cellulose chain, which could reasonably interpret the common sense that The treatment of liquid ammonia can be used to improve fiber flexibility. The mean square displacements (MSDs) and diffusion coefficients of ammonia rose with increasing temperatures. When the temperature rose from 298 K to 398 K, the diffusion coefficients of ammonia increased by 87.8%. So the appropriate elevated temperature could reduce the soak time and thus the production efficiency in treatment of liquid ammonia could be improved. The total number of hydrogen bonds in ammonia environment increased due to the forming of hydrogen bonds between ammonia and cellulose I. By adding ammonia, the number of intrachain hydrogen bonds in a cellulose chain remained unchanged, but interchain hydrogen bonds among cellulose chains were weakened, contributing to the stronger movement of cellulose chains and showing a good swelling property of cellulose.关键词：Cellulose I;Molecular dynamics simulation;Flexibility;Diffusion;Hydrogen bonds
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发布时间：2021-03-19 - 摘要：This research aimed to develop a novel polymeric micelle system to deliver iron oxide nanoparticles to tumor regions. To achieve the purpose above, the amphiphilic rentipede-like polymer poly(succinimide)-grafted-poly(ethylene glycol)-dodecylamine (PSI-g-PEG-DDA) was successfully synthesized. A study on structure and properties was conducted then through gel permeation chromatography (GPC) and nuclear magnetic resonance (1H-NMR). Through the phase transfer process, the amphiphilic polymer was used to encapsulate the superparamagnetic iron oxides (SPIOs) for preparing the stable water-soluble SPIOs. The product was found to form spherical micelles in aqueous media due to its amphiphilic nature with an average particle size of 50 nm measured by dynamic light scattering (DLS) and TEM imaging. Magnetization curve showed the water-soluble IONPs kept the superparamagnetic property of organic IONPs. An MTT assay showed no significant cytotoxicity of IONPs to HepG2 cells. Remarkably, MRI showed that IONPs displayed a clear concentration-dependent T2 signal reduction effect, with an R2 value of 187.3 (mmol/L)-1 s-1. The result of mice magnetic response imaging (MRI) in vivo showed that this new type of SPIOs caused a great enhancement effect on T2 magnetic resonance and long half-life in the circulation, which confirmed that it could be used as a potential contrast agent.关键词：Amphiphilic centipede-polymer;Micelle;Superparamagnetic iron oxides;Magnetic response imaging
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发布时间：2021-03-19 - 摘要：A silane coupling agent was obtained by reaction of (3-glycidyloxy-propyl)trimethoxysilane (A187) and N-phenyl-1,4-phenylenedi-amine (PPDA). Its structure was characterized by 1H-NMR, IR and MS. After that, different amounts of the silane coupling agent were used to in situ modify the silica to prepare antioxidant functionalized silica/NR composites. The processing ability, mechanical properties and antioxidation effect of the composites were compared with those of the carbon black/NR, neat silica/NR and bis(3-triethoxysilylpropyl) tetrasulfane (Si69) modified silica/NR composites. Cure characteristics and RPA results showed that the viscosity, the highest torque, optimum cure time and dispersion of filler of the antioxidant functionalized silica/NR were improved. The mechanical properties of the composites increased with increasing amount of silane coupling agent first, and then reached a plateau. When the amount of silane coupling agent was more than or equal to 10.8% (wt% to silica), the tensile strength of the composites was as high as that of carbon black/NR and Si69 modified silica/NR, which was much higher than that of neat silica/NR. Moreover, the tear strength of the composites was higher than that of all references. After air ageing at 100℃ for different days, the mechanical property retention of the antioxidant functionalized silica/NR was better than that of all references with antioxidant 4020, which illustrates that the new silane coupling agent has better ageing resistance than antioxidant 4020.关键词：Antioxidation;Silane coupling agent;Surface modification of silica;Silica/NR composites
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发布时间：2021-03-19 - 摘要：Alkali lignin/HDPE composites were prepared respectively with dioctyl phthalate (DOP), dibutyl phthalate (DBP) and epoxidised soybean oil (ESO). The influence of plasticizer on mechanical properties of composites was studied. The results showed that these plasticizers could increase the elongation at break of composites and DOP had the best effect. With adding 7.5 phr DOP, the elongation at break of composites was 146.28%, much higher than that(83.8%) of composites without DOP. Composites were prepared with different contents of DOP to study the influence of DOP on mechanical properties, fracture morphology and rheological properties of composites. The mechanical properties of composites showed that the increasing DOP content was beneficial to the increasing of elongation at break. The SEM showed that the fracture surfaces of composites became coarser with the addition of DOP, and the toughness of composites increased. The rheological properties showed that the addition of DOP can lower the apparent viscosity () and complex viscosity (*) of the composites, and the linear viscoelastic region turned narrow, the storage modulus (G') and the loss modulus (G) also gradually declined with the increasing DOP content. According to the analysis it was concluded that DOP can adsorb on the surface of lignin particles and suppress the agglomeration of lignin particles in HDPE, which may improve the dispersion of lignin particles in HDPE and reduce the interaction force between the lignin molecules and the molecular chains of PE, thus the mechanical properties and rheological properties of the composites were improved.关键词：Alkali lignin;HDPE;Composite;Plasticizing mechanism;Rheological behavior
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发布时间：2021-03-19 - 摘要：Exfoliated montmorillonite (MMT) and reduced graphene oxide(rGO) hybrids reinforced poly-(vinyl alcohol) (PVA) nanocomposites were prepared via a one-step method. The reduction of graphene oxide (GO) was directly performed in the presence of exfoliated MMT sheets, which effectively prevented the restack of graphene sheets in PVA aqueous solution. The results showed that the interfacial interaction between MMT-rGO hybrids and PVA matrix can be significantly improved by hydrogen bonds. The incorporation of MMT-rGO hybrids into PVA resulted in greatly enhanced tensile properties due to the well dispersion and strong interfacial interaction, which were higher than those of PVA nanocomposites with MMT or rGO individually. The influence of the ratio between MMT and rGO was also investigated. The tensile strength and Young's modulus of the 1 wt% MMT-rGO(2:1)/PVA composites are 85.1 MPa and 1627.8 MPa, respectively, which increased by 46% and 62% compared to those of pure PVA films. The method developed in this study makes an effective way to fabricate hybrid reinforcements for the preparation of high-performance polymer composites.关键词：PVA;MMT-rGO;Synergistic effect;Mechanical properties
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发布时间：2021-03-19 - 摘要：A novel fluorinated aromatic diamine monomer containing ether linkage, trifluoromethylphenyl and sulfonyl groups, 2,2'-bis［3-(4-trifluoromethylphenyl)-4-(4-amino-phenoxy)phenyl］sulfone 3, was successfully synthesized through free-radical substitution, Suzuki coupling and nucleophilic substitution reactions using bis(4-fluorophenyl)sulfone and N-bromosuccinimide (NBS) as starting material, and was characterized by IR spectroscpy and 1H-NMR. Then it was employed to prepare a series of fluorinated poly-(sulfone imide)s (PSI 5a~5c ) with various commercial aromatic dianhydrides via a one-step high-temperature polycondensation. IR and 1H-NMR spectra were used to investigate the chemical structure. The results confirmed that the structure of poly(sulfone imide)s was in good agreement with the proposed structure and the imidization was conducted completely. The properties of the polymers were characterized by GPC, TGA, DSC, UV etc. The PSI polymers having number average molecular weight of 70100~80000 and molecular weight distribution of 1.44~1.70 were obtained. These poly(sulfone imide)s exhibited an excellent solubility and optical property. They could be easily dissolved not only in some strong polar organic solvents, such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAC) and N,N-dimethylformamide (DMF), but also had good solubility in some low-boiling-point solvents, such as chloroform, dichloromethane and tetrahydrofuran (THF) at room temperature. Flexible and transparent membranes were obtained by solution casting. They gave the UV cutoff wavelengths between 366 and 330 nm and high transmittance at 450 nm. Furthermore, these poly(sulfone imide)s also showed good thermal and mechanical properties. The glass-transition temperatures (Tg) were in the range of 254~264℃ and their 10% weight loss temperatures were above 550℃ under ether nitrogen or air atmosphere. These poly(sulfone imide) films had tensile strengths of 87~92 MPa, elongations at break from 9% to 13%, and Young's modulus of 1.8~2.1 GPa. Moreover, all the films possessed good dielectric properties with low dielectric constants between 2.8 and 3.0 at 1 MHz frequency.关键词：Poly(sulfone imide)s;Trifluoromethyl;Solubility;Transparency;Dielectric constant
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发布时间：2021-03-19 - 摘要：To suppress the migration of epoxy fat acid methyl ester (EFAME) from plasticized PVC, EFAME, as an internal plasticizer, was covalently bound to poly(vinyl chloride) (PVC) chains via a special synthesis process. The carboxyl-containing PVC (PVC-TSA) was synthesized through nucleophilic substitution reaction between PVC and thiosalicylic acid (TSA), and then EFAME was added to react with PVC-TSA to gain the internally plasticized PVC (PVC-TSA-EFAME). Fourier transform infrared spectrometry (FTIR) and hydrogen spectrum nuclear magnetic resonance (1H-NMR) confirmed the structures of PVC-TSA and PVC-TSA-EFAME. The 1H-NMR data were further used to calculate the degree of modification. It was found that a degree of modification of 1.2 mol% was achieved using the method of this work. The glass transition temperature (Tg) determination was realized by means of differential scanning calorimetry (DSC). The Tgs of PVC and PVC-TSA-EFAME were respectively 81.4℃ and 37.8℃. Compared to PVC, the marked decrease of Tg was attributed to the introduction of EFAME which increased the flexibility of PVC chains. The extraction and fogging experiments showed that almost no extraction or atomization loss was detected in PVC-TSA-EFAME, which suggested that the migration of EFAME from the plasticized PVC was completely suppressed.关键词：PVC;Epoxy fat acid methyl ester;Graft modification;Internal plasticization;Migration
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发布时间：2021-03-19 - 摘要：Silver coated aminated polyacrylonitrile (Ag/APAN) nanofibrous composite membranes were prepared by a facile method that combined the electrospinning technique and electroless plating method. Amine modification was used to replace the environment-unfriendly sensitization, activation pretreatment used in traditional electroless plating and modify the surface of PAN nanofibers to prepare the aminated PAN (APAN) nanofiers, then electroless silver plating was applied on APAN nanofibrous surface to prepare Ag/APAN nanofibrous composite membranes. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used to characterize the morphology and structure of APAN and Ag/APAN nanofibrous membranes. The results demonstrated that Ag+ can be adsorbed on the APAN nanofibrous surface and reduced into metallic silver clusters by the amino group. These little amount of silver clusters acting as catalytic active centers can ignite the next electroless plating process resulting in silver layers deposited uniformly on the surfaces of APAN nanofibers. The prepared Ag/APAN nanofibrous composite membrane exhibited excellent catalytic performance in the reduction of o-nitroaniline with sodium borohydride as reducing agent and did not cause secondary pollution of the reaction system.关键词：Nanofibers;Electroless plating;Silver nanoparticle;Catalyst
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发布时间：2021-03-19 - 摘要：To increase number of labile sites on PVC and thus facilitate grafting from PVC by aids of free radical polymerization (FRP) under mild conditions, self-initiated, or bi-isopropyl thioxanthone (BIITX) and isopropylthioxanthone (ITX) initiated FRP of vinyl chloride (VC) in THF at 0℃ or 20℃ was carried out under UV irradiation.Influences of monomer concentration,incident light intensity, reaction time and temperature on monomer conversion, polymer molecular weight and its distribution were investigated. Radical ITX produced by dissociation of BIITX or by H abstraction of ITX from monomer could combine with a macroradical. This allowed ITX residues to be incorporated onto PVC via weak CC bonds which could be cleaved easily to regenerate radicals under UV light or heat stimuli, and thus yielded new labile sites on PVC for initiation. UV-Vis,1H-NMR and FTIR spectra analyses demonstrated the presence of labile chlorines and ITX residues on the resultant PVC, and indicated that PVC resulted from self-initiated or ITX initiated FRP contained great labile sites. Using the PVC as a macroinitiator, grafting polymerization of N,N-dimethylaminoethyl methacrylate (DMAEMA) in THF at 50℃ was started, and PVC-based graft copolymer (PVC-g-PDMAEMA) was synthesized. Compared with the initial PVC used, the graft copolymer achieved an increased molecular weight and narrowed molecular weight distribution.1H-NMR and FTIR analyses further confirmed the formation of PVC-based graft copolymer, and revealed that more labile chlorines or ITX residues on PVC favored initiation of graft polymerization. SEM and TEM observations showed that the graft copolymers containing more than 15 mol% (analyzed by 1H-NMR) of PDMAEMA segments could assemble into stable core-shell micelles in water (pH 3).The grafted hydrophilic PDMAEMA stretched towards aqueous media,forming the shell, while hydrophobic PVC portion coiled up to the core. This phenomenon suggested an amphiphilicity of the graft copolymers. In contrast, the copolymer with less content (only 0.15%) of grafted PDMAEMA could not form micelles due to its insufficient amphiphilicity.关键词：Photopolymerization;PVC;Macroinitiator;Graft copolymer;Amphiphilicity
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发布时间：2021-03-19 - 摘要：A novel chemical functionalized graphene (FG) was synthesized through facial covalent functionalization with ethanolamine, and the effects of experiment conditions on the properties of the product were investigated in detail. The results showed that the absorbance of the product increased with increasing the content of ethanolamine, reaction temperature, pH and reaction time, while the content of N in the product decreased accordingly. It was concluded that the optimal properties of ethanolamine functionalized graphene (EFG) were achieved when the mass ratio of ethanolamine to graphite oxide (GO) was 4.0, the reaction temperature was 50℃, the pH was 7.0 and the reaction time was 12 h. X-ray photoelectron spectroscopy (XPS) suggested that the ethanolamine could modify graphene and reduce graphene oxide simultaneously. Subsequently, the EFG/polyvinyl butyral (PVB) composite materials were prepared by two different ways, including solution blending method and in situ reduction method. Finally, The scanning electron microcopy, conductivity test, ultraviolet and visible spectroscopy (UV-Vis) and tensile test were performed to measure the morphology and properties of the EFG/PVB composites. It was illustrated that the introduction of EFG led to an improvement in the conductivity, the ultraviolet shielding ability and mechanical properties of PVB. Compared with the material through solution blending, the composite prepared by the in situ reduction had a better performance. When the content of the EFG reached 3.0 wt%, the composite showed a conductivity of about 10-3 S m-1, which is 106 higher than that of neat PVB. Meanwhile, the ultraviolet shielding ability reached 90% by only adding 1.0 wt% EFG.关键词：Ethanolamine;Functionalization;Graphene;Polyvinyl butyral;Composite material
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发布时间：2021-03-19 - 摘要：Sulfadiazine-containing dextran ligand (SD-Dextran-DTPA) was synthesized by the incorporation of diethylenetriaminepentaacetic acid (DTPA) and sulfadiazine (SD) as a tumor-targeting group into dextran. This ligand was further reacted with gadolinium chloride to produce tumor-targeting macromolecule gadolinium complex (SD-Dextran-DTPA-Gd). Experimental data of 1H-NMR, IR, UV, average particle sizes and zeta potential evidenced the formation of the dextran ligand and gadolinium complex. In vitro properties including the relaxivity, cell uptake assay and magnetic resonance imaging were also evaluated. In the aqueous solutions, the average diameter of the dextran ligand SD-Dextran-DTPA and complex SD-Dextran-DTPA-Gd increased when the concentration of their solutions decreased. Compared with Gd-DTPA, this tumor-targeting dextran gadolinium complex SD-Dextran-DTPA-Gd possessed obviously higher relaxation effectiveness due to a slowly tumbling system and an increase in rotational correlation time. The cell uptake assay indicated that SD-Dextran-DTPA-Gd had a high affinity to the H460, MDA-MB-231 and T40D tumor cells and can be taken up selectively by these tumor cells. Magnetic resonance imaging (MRI) tests showed that SD-Dextran-DTPA-Gd possessed the relaxation effectiveness higher than that of Gd-DTPA and can enhance the contrast of MR images of the tumor cells. Moreover, the T1 signal intensities of the MDA-MB-231 cell suspensions were obviously higher than those of the H460 and T40D cell suspensions. Therefore SD-Dextran-DTPA-Gd has shown the potential as a tumor-targeting contrast agent in MRI.
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发布时间：2021-03-19 - 摘要：PLGA microspheres were chosen as the carrier to overcome the limitations of application for parathyroid hormone related peptide (PTHrP) which can increase the number and viability of osteoblasts and promote bone formation with a low-dose,long time,intermittent administration.PLGA microspheres were prepared by a water-in-oil-in-water (W1/O/W2) double emulsion solvent evaporation and PTHrP1-34 was encapsulated to the microspheres by a technique with good sphericity and high efficiency.The micrographs of polyester microspheres were evaluated by scanning electron microscope (SEM).The polyester microspheres had a good spherical shape.PTHrP1-34 loaded microspheres exhibited a slow release behavior for about 25 days,which was accord with expection.The effect of PTHrP1-34 loaded microspheres on pre-osteoblastic proliferation was studied via cell proliferation evaluation experiments.The results demonstrated that PTHrP1-34 loaded PLGA microspheres can enhance the proliferation and differentiation of MC3T3 cell effectively.Alkaline phosphatase (ALP) quantification experiment was also performed to investigate the influence of differentiation.The cells incubated with PTHrP1-34 loaded PLGA microspheres exhibited higher ALP level which was related to the differentiation.In summary,PTHrP1-34 loaded PLGA microspheres show great potential as a promising delivering and releasing carriers for application of oral implantology.关键词：Parathyroid hormone related peptide;PLGA;Microspheres;Controlled-release
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发布时间：2021-03-19 - 摘要：The castor oil was converted into maleic acid ester (i.e. maleated castor oil, MACO) by the reaction with maleic anhydride. Afterwards, the resultant MACO was free-radically copolymerized with reactive diluents (styrene, St) and cured to form foam plastics through conventional foaming technique. By changing MACO/St ratio, mechanical properties and aerobic biodegradability of MACO foams can be easily adjusted. To understand the biodegradation mechanism of the castor oil based plastic foam, various characterization techniques were employed in a systematic way. Compost tests in laboratory soil combined with molecular characterizations demonstrated that the bio-foam has acquired excellent biodegradability. Destruction of the network structure of the castor oil based polymer resulted from fission of ester groups due to attack of microorganisms. The final product of compost tests proved to be carbon dioxide. Inoculation of fungi on the castor oil based polymer further revealed that the vegetable oil acted as carbon source of growth of aspergillus niger. Under the catalysis of lipase, castor oil, MACO and its foam were hydrolyzed to produce fatty acids. The results of different degradation tests matched each other, which not only confirmed biodegradability of MACO plastics, but also preliminarily revealed molecular mechanism of the biodegradation process.关键词：Castor oil;Foam plastics;Biodegradability;Molecular mechanism
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发布时间：2021-03-19
Research Article
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The Construction of Phase Diagrams for Coagulation Formation of the Wet Spinning of Polyimide Fibers
摘要：Based on the theory of membrane forming systems,the phase separation of polyimide wet spinning has been investigated.Poly(amic acid) (PAA) fibers were prepared by the wet spinning way.The structure and properties of fibers were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM).Experimental cloudpoints of PAA/N,N-dimethylacetamide (DMAc)/H2O systems could be achieved in the accessible low polymer content range by cloud-point titration.Linearized cloudpoint (LCP) curve correlations for ternary systems were used to extrapolate to higher polymer concentrations to produce a full-phase diagram at different temperatures.The effect of changing the monomers of PAA was discussed in detail.The results suggested that a linearized cloudpoint curve correlation held for the ternary systems undergoing liquid/liquid demixing.The fact that the intrinsic viscosity of the ternary system within a certain range had little effect on the phase diagram was discussed.By changing the monomers of PAA,the phase separation of the system showed different sensitivities to temperature.关键词：Poly(amic acid);Coagulation formation;Cloud point;Ternary phase diagram- 32
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发布时间：2021-03-19
Research Bulletin
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