最新刊期
卷 ， 期 2 ， 2011
- 摘要：In recent decades, gel polymer electrolytes (GPEs) have received renewed attention in several areas such as lithium-ion batteries, solar cells and super capacitors due to their promising application.GPEs, swollen in a liquid electrolyte becoming plasticized or a gelled polymer electrolyte, have attracted particular attention because they may provide lighter and safer batteries with longer shelf life, leak proof construction and easy fabrication into desired shape and size.However, GPEs still show poor mechanical strength due to the need for impregnation with the liquid electrolytes.This significant drawback of GPEs hinders their practical application.To overcome these problems, in this review, the up-to-date technologies such as composite gel polymer electrolyte (CGPEs) and porous polymer electrolytes (PPEs) based on the gel concept have been summarized.In the CGPEs, the role of a filler in the membrane is to provide surface groups as physical cross-linking centers for the polymer segments, and thus reduce the polymer reorganization tendency which establishes additional conducting pathways on the filler surface.As a result, the nanosized particles not only lead to better ionic conductivity but also interact with the polymer hosts to enhance the mechanical strength.In PGPEs, due to the existence of the porous structure, the lithium ions can migrate not only in gel electrolyte but also in liquid electrolyte stored in the pores, leading to higher ionic conductivity.In addition, the main characteristics of these gel polymer electrolytes were mentioned.Finally, the future directions are also pointed out.关键词：Gel polymer electrolyte;Lithium ion batteries;Composite gel polymer electrolyte;Porous gel polymer electrolyte;Ionic conductivity
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发布时间：2021-03-19
Reviews
- 摘要：In order to investigate the effects of low molecular weight organic additives containing phenol hydroxyl group on the crystallization, melting and mechanical properties of biodegradable aliphatic polyester, poly (butylene succinate) (PBS) and bisphenol A (BAP) were selected to blend via solution mixing method.Then 13C-NMR spectroscopy was used to probe the interaction between PBS and BPA, and the effects of BPA on the crystallization, melting, glassy transition temperature (Tg) and dynamic mechanical properties were investigated using DSC (differential scanning calorimetry) and DMTA (dynamic mechanical thermal nalysis) .The results indicate that hydrogen-bonding was formed between phenol hydroxyls in BPA and ester groups in PBS chain, leading to the decrease of crystallization ability and melting point for PBS, which is attributed to the formation of PBS-BPA complexes via intermolecular hydrogen-bonding that disrupts the regularity of the PBS chain structure.The storage modulus of PBS-BPA complexes decreases with the increase of BPA content above the glassy transition temperature due the decreasing of crystallization ability for PBS, while the maximun position of the loss factor shifts to high temperature.关键词：Polybutylene succinate;Biphenol A;Complexes;Hydrogen-bonding;Crystallization
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发布时间：2021-03-19 - 摘要：The organic pigment phthalocyanine blue (PB) was hydrophobic and compatible with monomer, it can be dispersed into monomer dispersion and monomer drops in primary particles form just through ultrasonic and strenuous stirring procedures.Thus a series of organic pigment microcapsules with high pigment encapsulated efficiency and sharp particles size distribution can be prepared via pre-polymerization treatment and in situ micro-suspension polymerization.It was found that the pre-polymerization treatment of monomer dispersion can effectively increase the viscosity of monomer drop phase in suspension and then improve its resistivity to tear, which is conducive to improving the polymerization stability and controlling the microcapsules particles size and size distribution.Optical microscope (OM) and transmission electron microscope (TEM) images of polymerization product show that almost all of the organic pigment particles have been successfully encapsules into pigment microcapsules in a homogeneous state, and thus the spheral microencapsules possess a typical ‘guava-like’structure characterization.It was also found from OM and dynamic light scattering (DLS) that the microencapsules particles size distribution can be controlled in a narrow level, and its mean size can be effectively adjusted in a rather large range just changing tricalciun phosphate (TCP) amount and stirring rate in the in situ micro-suspension polymerization.The microcapsules of pigment by adhesive polymer can remarkably improve the adhesion between the pigment and the target matrix, and simultaneously the dispersion of pigment particles on the matrix surface, thus the resulting organic pigment microcapsules are promising for a number of applications, e.g.pigment printing, pigment dyeing and ink printing.关键词：Organic pigment;Microcapsulation;in situ Micro-suspension polymerization;Morphology
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发布时间：2021-03-19 - 摘要：Poly[ (tetrafluoropropoxy) 2-x (trifluoroethoxy) x ]phosphazenes of different substituent ratio were synthesized via nucleophilic substitution of polydichlorophosphazene (PDCP) which was prepared by vacuum thermal ring-opening polymerization of hexachlorocyclotriphosphazene (HCCP) .The final substituted polyphosphazene products were purified through the THF-benzene precipitation.31 P-NMR was used to assure the purification.The polymer structure was characterized by 1H-NMR and FTIR.The glass transition temperature was detected by differential scanning calorimetry (DSC) .The molecular weight was determined by gel permeation chromatography (GPC) and the crystallinity was tested through X-ray diffraction (XRD) .Gas permeability coefficient of N2, O2, CH4, CO2, He and H2 in these polymers at 20℃ were measured by permeate gas pressure method.The results shown that four different poly [ (tetrafluoropropoxy) 2-x (trifluoroethoxy) x ] phosphazene products with different x-value of 1.53, 1.86, 1.75 and 0 were prepared respectively.The glass transition temperature of these polymers were-45.2℃, -45.2℃, -50.3℃ and-32.3℃, and the weight-average molecular weight were 1.2 × 105, 5.6 × 105, 2.6 × 105 and 6.0 × 105 respectively.Polymer with substituted ratio x = 1.53 showed higher gas permeability.Its permeability coefficient of H2, CO2, He and O2 were 55 barrer, 75 barrer, 40 barrer and 15 barrer respectively.The selectivity coefficient of H2/N2 was 11.7, which showed potentiality in ammonia synthesized industry.In addition, the selectivity coefficient of O2/N2 was 3.1, demonstrated a promising oxygen-enriching material.关键词：Poly[ (tetrafluoropropoxy) 2-x (trifluoroethoxy) x]phosphazene;Polyphosphazene;Synthesis;Gas permeability
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发布时间：2021-03-19 - 摘要：Novel synthetic strategies and methods have been developed for the synthesis of magnetic resonance imaging (MRI) contrasts.DTPA ligand, DOTA ligand and peptide dendrimer-based MRI probes with controllable structure were prepared.The third generation L-lysine dendrimers were synthesized by solution-phase synthesis method and convergent approach, and the primary amine groups on the surface of the dendrimers were protected by different groups.The ratio between Boc group and Cbz groups was 18 ∶ 6.The peptide dendrimers were selectively deprotected and reacted with DTPA or DOTA derivates in the presence of succinic anhydride to yield controllable ‘peripheral’functional dendrimer-based MRI contrast agents.The new compounds were confirmed by NMR, ESI-TOF MS and so on.The peptide dendrimer-based MRI probes possessing highly controlled structures and single molecular weight were tested at 1.5 T magnetic field in a clinical MRI scanner, and a 3-fold increase in T1 relaxivity to 12.53 Gd mmol.L-1.s-1 was noticed comparing to that of the clinical agent Gd-DTPA.The successful approach to synthesize the controllable dendrimer-based agent and the high T1 relaxivity of the agent opened an opportunity for the design of multifunctional dendritic contrasts for MRI.关键词：Peptide dendrimers;Gadolinium chelates;Magnetic resonance imaging probes;Relaxivity
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发布时间：2021-03-19 - 摘要：Narrow-disperse poly (styrene-co-n-butyl acrylate) (P (St-co-nBA) ) microspheres were prepared by dispersion copolymerization in a mixture medium of ethanol with water initiated by 2, 2′-azobisisobutyronitrile (AIBN) using poly (N-vinylpyrrolidone) (PVP) as a steric stabilizer.Products were characterized by 1H nuclear magnetic resonance (1H-NMR) , differential scanning calorimetry (DSC) , Fourier transfer infrared spectroscopy (FTIR) , scanning electron microscopy (SEM) and laser particle size analysis (LS) .The influences of comonomer ratio of nBA to St (nBA/St) , polymerization temperature, stabilizer content, media polarity and initiator concentration on particle size, size distribution and monomer conversion were examined.Results showed that with increasing molar ratio nBA/St, the particle size increased, but the size distribution broadened, and the monomer conversion decreased slightly, when the ratio nBA/St exceeded 20/80 it decreased rapidly.As the polymerization temperature increased from 60℃ to 75℃, the monomer conversion and the particle size all increased, but the size distribution broadened.When the temperature rised to 80℃ the particles had a tendency of merging with each other, at the same time the monomer conversion rate decreased.The content of stabilizer had no obvious effect on the monomer conversion rate, but the average size of particles decreased and the size distribution of particles narrowed with increasing the stabilizer content.The particle size and polydispersity initially decreased with the increase of EtOH/H2O ratio, passed through a minimum, and then increased.When EtOH/H2O mass ratio was 80/20 ～ 90/10, the size distribution of particles was narrow.With the increasing of initiator concentration, the monomer conversion rate and the particle size increased, while the size distribution broadened.At a well-controlled condition, the narrow-disperse particles in the size range of 0.7 ～ 2 μm were achieved.The SEM images indicated the copolymer particles were smooth on their spherical surface.The1H-NMR and FTIR spectra confirmed the polymerization between St and nBA.DSC experiments showed the glass transition temperature (Tg) of the copolymers in the range of 56.7 ～ 107.1℃.The copolymer’s composition and it’s Tg could be controlled by the ratio of the comonomers.关键词：Styrene;n-Butyl acrylate;Dispersion copolymerization;Microsphere;Preparation
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发布时间：2021-03-19 - 摘要：The crystallinity distribution of polymers has a significant dependence on injection processing and determines the part properties.Speed, pressure and temperature fields are obtained from 3D numerical simulation by employing GLS (Galerkin/least-squares) , SUPG (Streamline upwind/Petrov-Galerkin) and GGLS (Galerkin gradient least-squares) methods.The non-isothermal shear stress-induced crystallization kinetics models are proposed based on the hypothesis that shear stress induced orientation of polymer chains increases the equilibrium melting temperature.The relationship between crystallinity and injection processing is modeled.SUPG method is used for the stabilized finite element formulation of crystallinity evolution in flow.Simulations for polypropylene were carried out under different processing conditions such as different injection speeds and mold temperatures, melt temperatures, and the results show that crystallinity is very low and can be neglected when the filling stage is over because of short injection time and high melt temperature.Crystallinity distribution in the final part is determined by processing parameters which can be varied to bring on the special crystallinity distribution.Latent heat due to crystallization may often affect the temperature field very much during the cooling stage.关键词：Injection molding;Shear stress-induced;Crystallization kinetics;Crystallinity distribution;Latent heat
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发布时间：2021-03-19 - 摘要：The ternary copolymers of α-methyl styrene (AMS) /styrene (St) /maleic anhydride (MAH) (referred to as PASM) were synthesized by solution polymerization.The effects of factors, such as monomer composition, temperature and time of copolymerization, were studied systematically.The copolymers of PASM were characterized by gel permeation chromatography (GPC) , Fourier transform infrared spectroscopy (FTIR) and thermogravimetery (TG) .The results indicated that the lower AMS feed ratio led to higher molecular weights and higher monomer conversion as well.When the polymerization temperature went over 70℃, the depolymerization occurred.The higher the temperature, the more serious the depolymerization.TG revealed that thermal stability of the copolymers decreased with increasing the AMS content in the copolymers, which indicated that the degradation was mainly caused by the chain scission of AMS-containing structures.The graft reaction of PASM onto polypropylene (PP) in molten state was investigated, and the functionalized production was confirmed by the FTIR spectra.Through SEM, the in situ compatibilization of polypropylene/nylon 6 (PP/ Ny6) blends with PASM was observed.The results indicated that with little PASM (PP/Ny6/PASM = 80/20/ 3 wt%) being added into PP/Ny6 blends, the in situ compatibilization role can be found distinctly, and the domain of the dispersed phase Ny6 reduced significantly.关键词：Copolymer;Polypropylene;Nylon 6;Functionalization;in situ Compatibilization
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发布时间：2021-03-19 - 摘要：The synthesis of polycarbonate (PC) was carried out by using the melt transesterification of bisphenol A (BPA) and diphenyl carbonate (DPC) catalyzed respectively by NaOH and tetraethylammonium hydroxide (TEAH) .When the molar ratio of DPC to BPA was 1.05∶ 1 and that of catalysts to BPA was 5 × 10-4∶ 1, under the process conditions selected, polycarbonates with Mn of 1.69 × 104, Mw/Mn of 1.97 (catalyzed by NaOH) and M n of 1.23 × 104, M w/M n of 1.44 (catalyzed by TEAH) were produced.The variation of intrinsic viscosity of the PC samples and the liquidity of relevant melt flow in different stages of the reaction process were determined.The 1H-NMR spectroscopy, UV spectroscopy and HPLC were employed to analyze the Fries, Kolbe-Schmitt and isopropyl radical combination rearrangement.In different catalytic processes, all these rearrangements have different forming and varying conditions.It is observed that the Fries rearrangement is the one most prone to appear among the three kinds of rearrangement reactions, which exists in the entire NaOH-catalyzed process.Kolbe-Schmitt rearrangement is impacted significantly by the high-temperature and melt viscosity of the reaction system.Compared with NaOH, in the TEAH-catalyzed system, the molecular weight of polycarbonate is lower, the molecular weight distribution is narrower and the degree of Fries and Kolbe-Schmitt rearrangements is much lower.In both catalytic processes, no rearrangement products caused by the combination of isopropyl radicals were found.关键词：Plycarbonate;Fries rearrangement;Kolbe-Schmitt rearrangement
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发布时间：2021-03-19 - 摘要：The conformation of star polyelectrolytes is simulated as a function of solution quality β by adopting the molecular dynamics method.With the development of synthetic technique, various kinds of star polyelectrolytes are synthesized, and a great deal of experiments and simulations are performed.The choice of solvent ranges from good to poor, i.e.the β value from form 0.5 to 3.5.The effects that the solvent quality has on the density curve of monomer, mean square end-to-end distance, mean square radius of gyration, mean square displacements and the systematic osmolality are investigated.The results show that the conformation of star polyelectrolytes will shrink gradually along with the increase of the solvent quality β, and at the same time, the counterion diffusion ability in the system will decrease continuously;however its coagulative power will be strengthened;what ’s more, the systematic osmolality will also continually decrease.The electrostatic intensity’s effect on the conformation of star polyelectrolytes is also discussed, and the result shows that the conformation of star polyelectrolytes will shrink to a denser state with the increase of Bjerrum length (Lb) .At the end, the effects that the salt ion’s concentration has on the conformation of star polyelectrolytes is studied.It is concluded that the increase of the salt ion’s concentration will lead to the shrinkage of the conformation of star polyelectrolytes.关键词：Molecular dynamics;Star polyelectrolyte;Solvent quality;Counterions
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发布时间：2021-03-19 - 摘要：This work relates to the development of polymeric nanosilica hybrid materials with nanosilica as node, IPDI and PPG as link and acrylate as terminal group for photopolymerization.The preparation process was as follow:nanosilica was first reacted with isophorone diisocyanate (IPDI) , then extended the chain with polypropylene glycol (PPG) in proportion to the mole of NCO on the surface of silica, further terminated the left NCO groups with hydoxyethyl acrylate (HEA) .Characterization of preparation by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) showed that IPDI, PPG and HEA were grafted onto nanosilica with chemical bonds and the percentage of grafting based on silica could be up to 92.2%.The morphology analysis of nanosilica and modified nanosilica by scanning electron microscopy (SEM) disclosed that modified nanosilica had lower aggregation and the diameters of silica particles were 30 ～ 50 nm although the sizes of nanosilica hybrid materials were beyond nanomaterial definition.Added 3% modified nanosilica into coating and compared with the coating with the same amount unmodified nanosilica, it was found that the viscosity of the coating decreased from 55 mPa.s to 48 mPa.s at 25℃ due to improvement of the compatibility of modified nanosilica with acrylic matrix, the conversion of C C double bonds in coating increased at the same UV curing time because of modified nanosilica’s better distributive performance in coating and lower scattering property for UV rays.After being cured, the pencil hardness of films increased from 3 H to 4 H and the weight loss decreased from 6.2 mg to 4.6 mg after 300 r/min abrasion due to a strong Si— O—Si bonding formed with network of film after polymeric nanosilica hybrid materials were used.关键词：Nanosilica;Modification with grafting method;UV curable;Property
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发布时间：2021-03-19 - 摘要：The aggregation behavior of the amphiphilic poly (amidoamine) (PAMAM) dendrons (ABn-Nap, Dan-ABn and Dan-ABn-Nap, n denotes the generation of the dendrons, Dan = Dansyl, Nap = Naphthyl) in water was explored and their energy transfer property was studied by using UV-Vis, fluorescence spectroscopy and transmission electron microscopy (TEM) .It was found that the modified dendritic molecules aggregated to irregular sphere-like assemblies with the size range of 150 ～ 650 nm.The critical aggregation concentration (CAC) values of ABn-Nap and Dan-ABn-Nap decreased with the generation of dendron increasing, which indicated the enhanced aggregation ability of them.Specially, Dan-AB4 displayed the lowest CAC value, indicating the dendron possessed an appropriate hydrophilic-hydrophobic balance that was a key factor for the aggregation.Notably, the efficient energy transfer occurred from the peripheral naphthyl groups to the focal dansyl unit in the aggregates.While Dan-ABn-Nap aggregates were excited at 282 nm, the fluorescence of naphthyl groups was quenched greatly, instead, strong fluorescence (400 ～ 650 nm) of dansyl groups appeared.The energy transfer efficiencies of different generation dendrons at different concentrations in water were calculated by using Frster theory.Energy transfer occurred with low efficiency when the concentration of dendrons was lower than CAC, for example, the energy transfer efficiency of Dan-AB8-Nap was only 5.7% at the concentration of 1.0 × 10-7 mol/L.However, when the concentration was above CAC (1.0 × 10-4 mol/ L) , the energy transfer efficiency improved greatly (77.1%) .Interestingly, the energy transfer efficiency of the aggregates in water was higher than that in organic solution at the same concentration.These results can be attributed to the more ordered stacking of the chromophores, closer distance between chromophores and both intermolecular and intramolecular energy transfer in the aggregates.关键词：Poly (amidoamine) dendons;Spherical aggregates;Energy transfer;Naphthyl;Dansyl
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发布时间：2021-03-19 - 摘要：Dynamic rheological properties of multi-walled carbon nanotubes (MWCNTs) filled polystyrene (PS) melt were investigated in relation to a two phase model proposed by authors.The linear viscoelastic behavior of the composites is related to the strain amplification effect of the bulky polymer phase far away from the filler inclusions and the relaxation of the filler phase.Dependence of strain amplification factor (Af) on MWCNTs volume fraction (φ) at different temperatures accords with the diffusion-controlled cluster-cluster aggregation (CCA) model.At φ < 0.020, MWCNTs are rather homogeneously dispersed in the matrix, and no remarkable change appears in the relation between Af and φ with increasing temperature.Af decreases obviously with increasing temperature at higher φ where MWCNTs form cluster aggregates.Characteristic dynamic moduli (G′f1 and G″f0) of the filler phase as a function of temperature follow Arrhenius law with the corresponding activation energies (E′a and E″a) varying discontinuously at φ = 0.025, suggesting that the temperature dependence of viscoelasticity of the homogeneously dispersed MWCNTs at φ < 0.020 is considerably different from that of the MWCNTs percolation network at φ > 0.025.The viscoelastic percolation is closely related to the conduction percolation, and the discontinuous variations of activation energies in range from 0.020 to 0.025 appear in the vicinity of the upper limit of the conduction percolation threshold.The dispersion of MWCNTs in the matrix has been verified in transmission electron microscope (TEM) observation.关键词：Two phase model;Multi-walled carbon nanotubes;Polystyrene;Composites;Dynamic rheological properties;Percolation
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发布时间：2021-03-19
Research Article
- 摘要：Reaction of 3′-trifluoromethyl-2, 2, 2-trifluroacetophenone (1) with toluene in the presence of concentrated sulfuric acid and 3-mercaptopropionic acid at reaction temperature of 40 ～ 50℃ for 8 h afforded 1, 1-bis (4-tolyl) -1- (3′-trifluoromethylphenyl) -2, 2, 2-trifluoroethane (2) , which was further oxidized to 1, 1-bis (4-carboxyphenyl) -1- (3′-trifluoromethylphenyl) -2, 2, 2-trifluoroethane (3) using oxygen catalyzed by N-bromosuccinimde (NBS) under photoirradiation in 77.4% overall yield.Then the nucleophilic substitution solution polycondensation of diacid 3 with 9, 9-bis[4- (4-aminophenoxy) phenyl]xanthene using Yamazaki method yielded a new polyamide containing trifluoromethyl and xanthene groups with high molecular weight (the number-average molecular weight is 43000, the polydispersity index is 1.8) .The polymer was amorphous and exhibited high transparency with an ultraviolet-visible absorption cut-off wavelength at 330 nm.This polyamide showed a glass transition temperature (Tg) of 242℃, decomposition temperature (Td) at 5% weight loss of 465℃ and char yield of 50% at 800℃ in N2.This new polyamide was readily soluble in organic solvents such as N, N-dimethylacetamide (DMAc) , N, N-methyl-2-pyrrolidone (NMP) , m-cresol, pyridine and tetrahydrofuran.Transparent, flexible, and tough films of the polymer cast from DMAc solution exhibited tensile strength of 85 MPa, elongation at break of 10% and tensile modulus of 2.0 GPa.The electrical properties of this polymer such as the volume resistivity of 2.85 × 1015 Ωcm, surface resistivity of 4.23 × 1014 Ω and dielectric constant of 3.55 (100 Hz) indicated its excelllent electrical resistance property.
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发布时间：2021-03-19
Research Bulletin
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