最新刊期
卷 ， 期 4 ， 2002
- 摘要：The coupling reaction of butadiene-styrene anionic living coploymerization system with acryloyl chloride (AC) in extracted oil have been studied．Various factors related to the coupling reaction,such as AC／BuLi(mole ratio),reaction time,reaction temperature,relative molecular weight of the living copolymer,amount of THF,end group ot the living copolymer,monomer concentration,were investigated．Coupling efficiency and branching number were dramatically effected by AC／BuLi(mole ratio)；when 0.7≤AC／BuLi≤10,the coupling efficiency was higher than 50％ and the average branching number was higher than 3；while AC／BuLi was less than 0.7 or higher than 10,the obtained polymer was with poor coupling efficiency and the branching number was decreased．Coupling efficiency was decreased when the molecular weight of living copolymer or the temperature of coupling reaction was increased；coupling efficiency was increased while the time of coupling reaction or the amount of THF was increased；the monomer concentration was little effect on coupling efficiency；when the end group of the living copolymer was butadiene,the resulted polymer was with higher coupling efficiency but lower branching number；when the end group of the living copolymer was styrene,the obtained polymer was with lower coupling efficiency but higher branching number．The optimism conditions of the coupling reaction were established,that is AC／BuLi=0.7～10(mole ratio),reaction time 60 min,reaction temperature 50～70℃,THF／BuLi≤50(mole ration),[M]=11 wt％,the branching number and the coupling efficiency of the obtained polymer were 2.3～8.0 and 50％～80％ respectively．
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发布时间：2021-03-19 - 摘要：Hydrogels based on n-alkyl methacrylate esters (n-AMA) of various chain lengths,acrylic acid and acrylamide cross-linked with 4,4′-di (methacryloylmino) azobenzene were synthesized．The structure of three-dimensional network was characterized by the modulus of elasticity,by the effective network density and by the interaction between polymer and water．The equilibrium swelling behavior of the hydrogels in buffered solutions at pH 2.2 and pH 7.4 and the biodegradability in vivo of their azobenzene cross-linking groups as well as the mechanism of degradation by cecal bacteria were studied．The gels neither swelled nor degraded in the stomach broth；but in the medium of cecum their azobenzene cross-linking groups were degradable by anaerobes present in the cecum．The rates of degradation were found to be related to the equilibrium degree of swelling．The factors influencing the degree of swelling were also shown to influence the rates of gel degradation．By adjusting these factors including the degree of cross-linking,the lengths／content of the n-AMA side chains,it is possible to control both the degree of swelling and the degradation in vivo of the azobenzene cross-linking groups．Thus these hydrogels have potential for colon-specific delivery of drugs．
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发布时间：2021-03-19 - 摘要：Polyelectrolyte hydrogels based on n-alkyl methacrylate esters(n-AMA),acrylic acid and acrylamide cross-linked with 4,4′-di(methacryloylmino)azobenzene were prepared．The deswelling of gels was observed under non-contact electric fields,while the gels with the longer hydrophobic side-chains proceeded as welling before deswelling．The gels first bend toward the cathode under non-contact electric fields,and the direction or degree of bending waves with the passage of time or when higher voltages are applied. The gels can turn back to the swollen shape when the electric field is removed．These properties of the gels are related to electro-osmosis,electrodiffusion,electrolysis,and hydrophobic interactions．
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发布时间：2021-03-19 - 摘要：The electroconductive polymer with new function and characteristic can be synthesized by the electrochemical polymerization．This new functional material can be widely used in catalyst,electrochemical sensor and electroanalysis etc．So the film of EPU-Cu2+ coordination polymer was obtained by the reaction between CuCl2 in isopropyl alcohol solution and EPU．The EPU-Cu2+ film was characterized by ESR,FT-IR,XPS,elemental analysis and AES,and the composition and structure of the film were determined．Each Cu2+ ion is coordinated by hydroxyl from two units in EPU molecule．The Cu2+ content in the coordination polymer is 8.63％．The experiments indicated that,the EPU-Cu2+ film activated by Na2SO3 can catalyze polymerization of VAc in water phase at room temperature．The effects of temperature,concentration of Na2SO3 and VAc,weight of copper electropolyurushiol complex membrane on the polymerization rate and induction time were investigated．The polymerization rate equation can be expressed as：Rp=0.07e-2825/RT[VAc]1.54[Na2SO3]0.5．The experimental results indicate：the induction period for polymerization is 122 s,the yield of VAc is equal to abeut 79％ after 24 h,and Mw,Mn and Mw／Mn of PVAc is l.26×106,2.63×105 and 4.79,respectively．
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发布时间：2021-03-19 - 摘要：Electron beam (EB) curing of polymer matrix composites offers many particular advantages compared to conventional thermal curing．There has been a considerable development about the EB curing advanced composites for the use of aerospace and other industries in recent years．Most variety of epoxy resin has been confirmed to possess radiation reactivity and have already become chief resin matrix used in EB curable composites．The dynamic mechanical analyses on EB-cured epoxy resin were made in the paper．Epoxy resins with varied chemical structure,molecular weight and distribution index were used in the EB radiation experiment．The variation regularities of gel fraction,damping factor and dynamic modulus for different samples were studied．The experimental results indicate that the radiation reactivity of epoxy resins is directly associated with their chemical structures．Phenolic aldehyde epoxy resin exhibits high radiation reactivity,glass transition temperature and high temperature modulus after curing. But the radiation reactivity of alicyclic epoxy resin is low．The curing level of epoxy resin descends slightly with increasing molecular weight under low radiation dosage,but the glass transition temperature is enhanced．The molecular weight has a little influence on the enhanced extent of curing level with increasing radiation dosage and the degree of homogeneity in cross-linked structure is improved for samples with high molecular weight．The glass transition temperature is under the influence of curing density at high reaction level．Similarly,the curing density is key factor to determine modulus of cured samples,but the molecular weight plays chief role in the samples with similar curing density．The reaction extent in sample with high polydispersity is higher under same radiation dosage,but the degree of homogeneity in cross-linked structure is lower than that of low polydispersity sample．
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发布时间：2021-03-19 - 摘要：Spherical polypropylene (PP) granules of high porosity were synthesized using a spherical high yield TiCl4,／MgCl2 supported catalyst．As much as 50 wt％ of styrene (St)／benzoyl peroxide (BPO) mixture (based on PP weight) was adsorbed into the PP granules,and solid phase graft polymerization of St was conducted under different conditions. Effects of various reaction parameters,such as St／PP weight ratio,BPO／St ratio,reaction temperature,and reaction time on the amount of grafted PS in PP,graft efficiency,and the molecular weight of product were investigated．The structure and phase morphology of the produced PP/PP-g-PS alloy was characterized by infrared (FTIR),differential scanning calorimetry (DSC),GPC,viscometry and polarized microscope (PLM)．The results showed that solid phase graft polymerization of St in PP granule produced PP/PP-g-PS／PS alloy with high amount of grafted PS (maximum 24.3 wt％ of PS based on PP／PP-g-PS) and high graft efficiency (maximum 56.7％)．The size of PP crystals was greatly reduced after grafting PS on PP．The final product is still in the form of regular spherical granules,which is beneficial to industrial process．Under the studied conditions,there was slight degradation of the PP chains in the graft reaction．
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发布时间：2021-03-19 - 摘要：The copolymerization of 4-vinyl pyridine (4-VP) with acrylamide (AM) has been realized by radical copolymerixation in solution using potassium porsulfate as initiator．The effects of acetone／water and DMF／water solvent systems,comonomer concentration,polymerization temperature,polymerization time and initiator amount on the conversion of the polymerization and molecular weight were investigated in detail．The results showed that the mixed solvent DMF／water=1 (V/V) is suitable for the copolymerization of 4-VP and AM．The composition of copolymer was determined by ultraviolet spectrophotometry and the structure of copolymer was characterized and verified by FTIR and 13C-NMR．Finally,The monomer reactivity ratios of 4-VP and AM were obtained with Kelen-Tudos method,r4-VP=0.644,rAM=0.371．
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发布时间：2021-03-19 - 摘要：Narrowly distributed emulsifier-free cationic polymethylmethacrylate latex particles were prepared by using microwave irradiation in the presence of initiator 2,2′-azobis isobutyramidine dihydrochloride．The effects of initiator concentration,monomer concentration,ionic strength and heating method on the size,shape and stability of latex particles were discussed．Results showed that the average particle size increased with increasing the monomer concentration and ionic strength．The stability of latex had similar tendency of chage．However,it initially decreased with the increase of the initiator concentration,passed through a minimum,and then increased．In comparison with the conventional heating method,using microwave irradiation increased reaction rate and number of particles,and decreased particle diameter．No constant rate stage existed in the reaction．The method presented here is useful to prepare other type of latex particles.
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发布时间：2021-03-19 - 摘要：Poly(N-vinylisobutyramide) (PNVIBA) macromonomer was synthesized by free radical polymerizafion of N-vinylisobutyramide in the presence of AIBN and using p-chrolomethylstyrene as end capping agent．The molecular weight of PNVIBA can be controlled based on the process of prepared NVIBA oligomers by changing concentration of 2-mercaptethanol．The PNVIBA macromonomers exhibit remarkable thermosensitive properties for temperature change in aqueous solution．The PNVIBA grafted polystyrene(PNVIBA-g-PSt) polymeric nanoparticles were prepared by the free radical dispersion copolymerization of PNVIBA macromonomer and styrene in ethanol or ethanol/water mixed solvents．The effects of molecular weight and concentration of the macromonomer and composition of solvents on the particle size and morphology of the PNVIBA-g-PSt nanoparticles were studied．Changing macromonomer concentration and reaction condition could control the particle size in diameter and morphologies of the nanoparticles．
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发布时间：2021-03-19 - 摘要：With anhydrous aluminum trichloride as Friedel-Crafts catalyst,the postcrosslinking reaction of macroporous St-DVB copolymers in the presence of carbon tetrachloride was investigated．The results show that the synthesis conditions for the starting copolymers,including the DVB content,the type and amount of the porogens,play an important role in forming the pore structure of the postcrosslinked products．When the starting copolymers with relatively high DVB content were synthesized using good solvent(toluene) as porogen,the specific surface area for the postcrosslinked products could reach the value of 1000 m2／g or higher．The postcrosslinking reaction, generally,increases the pore volume,decreases the average pore diameter,and greatly increases the stability of pore structure of the resulted products．The role of the carbon tetrachloride as a crosslinker,at relatively low DVB contents of the starting copolymers,could be confirmed by the C=O group peaks in IR spectra of the postcrosslinked products．On the other hand,an alkylation reaction of the pendant vinyl groups with neighboring aromatic rings is believed to dominate the course of the postcrosslinking at high level of DVB content,as manifested by the good correlation of the consumption of pendant vinyl group with the increment of specific surface area of the copolymers after postcrosslinking reaction．
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发布时间：2021-03-19 - 摘要：The nanocomposite of phenolic resin／hexamethylenetetramine／montmorillonite,which was obtained by the treatment of inorganic montmorillonite,are prepared by casting and curing,and phenol resin exhibit crosslinked chains by chemical bonds forming a three-dimensional network while the mechanisms of phenol resin are different. As a result,it has been investigated by X-ray diffraction(XRD) that the peak of 16-MMT(2θ=4.02。) disappeared,and the first peak(n=1) of montmorillonite at the resol phenol resin／16-MMT appeared at 2θ=2.50～2.56。,while the diffraction peak of montmorillonite at the novolac resin／16-MMT has not easily bee found. Thus,resol type of resin can form the intercalated nanocomposite with the lattice spacing of 3.53～3.45 nm,while novolac phenolic resin can partly form the exfoliated nanocomposite．The curing reaction of novolac phenolic resin has been studied by differential scanning calorimetry (DSC) at various heating rates. Some kinetics parameters including the reaction order and activation energy were calculated with Kissinger,Flynn-Wall-Ozawa and Crane methods. The curing kinetic of novolac phenol resin gives information that activation energy and reaction order decrease with the addition of organic montmorillonite．The value of E obtained for the neat novolac resin was 162.3 kJ／mol,and those of the systems with 5,7 and 10 percents of organic montmorillonite were 139.2,142.8 and 122.6 kJ／mol,respectively．It was observed that the reaction order of the pure system was 1.13,and the systems with 5,7 and 10 percents of organic montmorillonite were 0.95,0.92,0.95．With the reduction of the activation energy and the raction order,it is possible to take advantage to the application of nanocomposite．
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发布时间：2021-03-19 - 摘要：Aggregation behaviors of two anionic azo polyelectrolytes with different chemical structures were studied in the tetraphydrofuran(THF)／water mixture．The aggregating process was traced by UV-Vis absorption spectroscopy and the aggregates formed were imaged with transmission electron microscopy(TEM)．The pH effect on the aggregation was also investigated．With the increasing of water content in THF／water mixture,the azo chromohpores in the polyelectrolytes aggregate gradually,which results in an obvious blue-shift of the absorption maximum and a decrease of absorption intensity in the UV-Vis spectra．In the solutions with high concentration of azo polyelectrolytes,the aggregates were visualized with TEM to be nano particles with average diameter of about 80 nm．Results shows that the aggregates are much more stable than the related aggragates formed form small azo functionalized amphiphile．In addition,due to the difference in the architecture style of zao chromophores and carboxyl groups,pH of the medium has an opposite effect on the PCAPE and PPAPE aggregates．
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发布时间：2021-03-19 - 摘要：The PVT data of five kinds of biaxially oriented polypropylene (BOPP) Resins was measured by the PVT-100 apparatus．Thermal expansion coefficients (α) and isothermal compressibility (β) were evaluated from Tait equation in the melting state and then compared with those fitted with the value of experiment．The results showed that it was reasonable to calculate α and β with Tait equation in the melting state．At the same time,it was found that thermal expansion coefficients,isothermal compressibility and the melting temperature (Tm) of one of BOPP melts (S28C) were lower than those of the others in the same test conditions,indicating that the volume deformation of S28C resin is less so that it could be realized to avoid arising surface defects of the film (biaxially oriented polypropylene film) due to contracting,thereby decrease damage to the film in the subsequence process．Accordingly superior processing properties of S28C resin are confirmed from PVT speciality．
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发布时间：2021-03-19 - 摘要：Nylon66／montmorillonite composites with 2.5 wt％ and 4.5 wt％ clay loading have been prepared by melt process．Non-isothermal and isothermal crystallization behavior of the samples has been investigated by dynamic scanning calorimeter (DSC),compared with that of pure nylon66．The results have shown that the presence of montmorillonite particles displays a high propensity to nucleate nylon66 crystallization and enhances the crystallization rate of nylon66．But the strong interaction between nylon66 and montmorillonite restricts the motion of nylon macromolecular segments,which thus leading to the increase of the activation energy of crystallization．The behavior of crystallization with the different filler contents has changed slightly．And the temperature range from 228℃ to 234℃ is an insensitive-temperature region of crystallization for composite．Liu’s method is suitable for investigating the non-isothermal process,but Ozawa’s method is not．
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发布时间：2021-03-19 - 摘要：Three(a),(b),(c) samples of luminescent Eu-containing copolymer (NaEu(Ⅲ)-TTA-PSAA) was synthesized through the reaction of copolymer of acrylic acid and styrene (PSAA,Mw=3000) with metalorganic complex(NaEu(TTA)4),which was obtained between Eu and thienyltrifluroacetone．These samples of coordination polymers were characterized by FT-IR,UV,XPS and DTA-TG,and its composition and their structure were determinated. The result of electrical conductivity methods and elemental analysis indicated that there were different compositions and structures of these coordination polymers in different pH．The results of elemental analysis show that the content of Eu3+ in sample (a),(b),(c) was 11.89％,12.55％ and 13.41％ respectively．It was ascertained in these coordination polymers each Eu3+ is coordinated by TTA- ion and carboxyl in the PSAA molecule,making these coordination polymers cross-link further．As a result,these coordination polymers,which are insoluble in most orgainc solvents and higher thermal resistance,are brown solids．But it can he soluble in N,N-dimethylformamide and the mixed solvent of glycerol alcohol and isopropanol．The coordination polymer exhibited intense red light at 615 nm under UV excitation at room temperature,which is attributed to the 5D0→7F2 transition of Eu(Ⅲ) ions．The effects of solvents and pH on the fluorescence intensity were investigated．The fluorescence spectrum indicated that the coordination polymer has good fluorescence properties as pH=10.0．
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发布时间：2021-03-19 - 摘要：Copolymer of acrylamide and 4-vinyl pyridine (CPAV),which had been synthesized by radical copolymetization in solution of DMF／water(volume／volume=1:1) using potassium persulfate as initiator,was quaternarized using dimethyl sulphate,and a series of copolymers having pendent quaternary pyridinium group have been synthesized,which have different degree of cationization and different molecular weight．The cationic copolymerwas characterized by FTIR,13C-NMR and UV analysis and its flocculation and corrosion inhibition properties were studied in detail．The cationic copolymers QCPAV displayed good properties in the experiments．The experimental results of flocculation for siliceous earth suspension showed that the transmittance of the supernatant layer of the siliceous earth suspension after being flocculated could come up to 100％；without need of adding any other coagulation aids．QCPAV has good flocculation effect under weak alkline condition (Optimum pH is about 8 and Optimum added amount is 1×10-6～2×10-6 g/g),and its performance was superior to that of non-ion polyacrylamide(PAM)．The experiments results of corrosion inhibition in 0.5 mol／L sulfuric acid solution showed that QCPAV was effective for the corrosion prevention of A3 steel in sulfuric acid solution and corrosion inhibition rate to steel A3 can reach 85％．It was found that the higher the degree of cationization is,the better flocculation and corrosion inhibition functions is,and the molecular weight of the copolymers also affects these functions obviously．The research results of the flocculation mechanism showed that the reason that the QCPAV has good flocculation property is the synergistic reaction of charge neutralization and bridging absorption．In the research of corrosion inhibition mechanism,the conclusions could be arrived at that QCPAV could form a compact adsorption film on the mental surface．The formation process of the film was closely associated with the physisorption through electrostatic gravitation and the chemisorption through coordination of π electrons of pyridine and d orbit of atom Fe．
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发布时间：2021-03-19 - 摘要：A method of using microporous filter membrane (nuclepore membrane) to filtrate a dilute solution under low pressure is established to study the size and conformation of linked polymer coils (LPC) in solution made up of the low concentration partially hydrolyzed polyacrylamide (HPAM) and aluminum citrate (AlCit,crooslinker)．The results show that the LPC is spherical．Because of the crosslinking the metamorphism of the LPc under shear is limited．Integrating the method of filtration with dynamic light scattering (DLS) and scanning electron microscope (SEM) could reveal the size distribution of the LPC．The results show that the diameter of the LPC in solution (the relative molecular weight of HPAM is 1.1×107～1.4×107,the concentration of HPAM is 0.02％,the concentration of NaCl is 0.2％,the mass ratio of HPAM to Al is 20:1) is less than 1.38 μm,the diameter of a few LPC is more than 450 nm,and the mean hydrodynamic diameter of the LPC is 492 nm．In this range of concentration of HPAM and with the same experimental condition,the higher the relative molecular weight of HPAM,the larger the size of the LPC．Since the shrinkage of the LPC on glass sheets after drying spontaneously is limited the photographs of SEM of the LPC could describe the real size distribution of the LPC．
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发布时间：2021-03-19 - 摘要：The cationic polymerizations of isobutylene (IB) initiated by MeOH／BF3 system in CH2Cl2 were carried out at various temperatures (Tp) from -100℃ to -50℃ in the presence of different concentrations of water ([H2O]) from 1.5×10-3 mol／L to 4.6×10-3 mol／L in the polymerization systems．The effects of [H2O] and Tp on the conversion,molecular weight and molecular weight distribution (MWD) of the product polyisobutylene (PIB) were investigated in order to make use of the trace of water which is impossible to remove from the polymerization system．The equations based on molecular weight with Tp were obtained and the corresponding active energy of degree of polymerization (Ep) were also calculated at [H2O] of 1.5×10-3 mol／L,2.2×10-3 mol／L,2.9×10-3 mol／L,3.5×10-3 mol／L and 4.6×10-3 mol／L respectively．The results showed that both [H2O] and Tp did affect the cationic polymerization of IB and the molecular parameters of PIB．In the cases of different [H2O] of 1.5×10-3 mol／L,2.2×10-3 mol／L and 3.5×10-3 mol／L,the conversions increased with Tp from -lOO℃ to -80℃,reached the maximum around -70℃～-80℃,and then decreased with Tp from -70℃ to -50℃．It was shown that Tp affect on molecular weight more obviously at low [H2O] than that at high [H2O]．Molecular weight increased and MWD narrowed with decreasing Tp and／or [H2O]．On the other hand,traces of water in the polymerization systems did the disadvantageous effects on the IB cationic polymerization．All Ep was minus at different [H2O] and it increased from -40kJ／mol to -17 kJ／mol when [H2O] increased from 1.5×10-3 mol／L to 4.6×10-3 mol／L．It indicates that the disadvantageous influences of H2O on the polymerization processes,the molecular weight and its distribution would become more serious when [H2O] and/or Tp increased．H2O restrained the propagation of polymer chain and accelerated the side reactions of active centers,such as chain transfer reaction and termination,which leading to low molecular weight and broad molecular weight distribution．
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发布时间：2021-03-19 - 摘要：Much work over the last 10 years has focused on composites that exhibit a change in composition and structure over a nanometer length scale．Layered silicates like montmorillonite(MMT) dispersed as a reinforcing phase in a polymer matrix are one of the most important forms of such organic-inorganic nanocomposites to afford remarkable property enhancements relative to conventionally-scaled composites．This paper focused on preparation of PVAc／organic-MMT nanocomposite by γ-ray radiation polymerization．Being organized,affinity of montmorillonite (MMT) to organic substance is improved,and the molecular of VAc penetrate into layers of montmorillonite in this experiment．The intercalation polymerization was initiated by γ-ray radiation．In this process,the layers of montmorillonite were exfoliated and PVAc/organic-MMT nanocomposite was formed．XRD patterns shown after polymerization the d(001) basal spacing of MMT uptake from 2.44 to 3.68 or 4.41 nanometer．This indicated that the montmorillonite were exfoliated into layers of nanoparticles and dispersed in PVAc matrix．FT-IR spectrum shown the characteristic absorption of PVAc in the MMT particles separated from the nanocomposite and the position of peaks shift to high wavenumbers．This shown there is polymer phase in the MMT particles and there is an interaction between PVAc and MMT nanoparticles．SEM and TEM have also proved that the PVAc／organic-MMT is a kind of nanocomposite．We also have studied the tensile atrength and tensile elongation of PVAc／organic-MMT nanocomposites and the PVAc/organic-MMT blends．The results show that the nanocomposite have high tensile strength and tensile elongation than blends when the amount of MMT is same．
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发布时间：2021-03-19 - 摘要：Starch was partially acetylated by acetic anhydride in the presence of pyridine and N,N-dimethylformide (DMF),which was used as an activator,and starch acetate (St-Ac) with substituting degree (DS) about 0.7～1.9 was obtained．The effect of the solvating time by DMF and quantity of acetic anhydride on DS was studied．Graft polymerization of ε-caprolactone (ε-CL) onto starch acetate was carried out through anionic ring-opening polymerization of ε-CL in diethylene glycol dimethyl ether solution．The graft polymerization was initiated by—ONa groups which were formed through the reaction of the remained—OH groups in St-Ac with naphthalene sodium (NS)．The grafting reaction was characterized by grafting percentage,monomer conversion,as well as gel permeation chromatography (GPC) through comparison of the Mn,Mwand Mw／Mn of St-Ac with that of the grafted copolymer,starch grafted polycaprolactone (St-g-PCL)．The influence of the reaction temperature,monomer and NS concentrations on the grafting percentage and the monomer conversion was discussed．The results showed that the grafting percentage and the monomer conversion vary in a way of S curves as grafting temperature increased from 50℃ to 150℃,but increase with the increasing of the monomer concentration and NS concentration．
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发布时间：2021-03-19 - 摘要：The native conformations and thermodynamic properties of compact polymers with chain length N(N≤22) are investigated by using exact enumeration calculation method and Monte Carlo simulation method employing the HP model．The average Helmholtz free energy 〈F〉 and average partition function 〈Z〉 can be expressed in the form of〈F〉=aN+b,ln〈Z〉=a′N+b′,where N is chain length of compact chains a,b and a′,b′ only depend on temperature．We also find that the compact chains with unique ground states have similar relationship in the thermodynamic property and the chain length．In the HP model,the number of sequences of conformations for a protein of chain length N is 2N+1,and the number of sequences with unique ground state may be expressed as NS：NS=a×2N+1 (a=0.025)．In these HP sequences,the sequences with 40％～60％ in the percentage of Hresidue have a large probability of emergence．We find that many structures are the same in those unique ground state,and the values of degeneration of structure are 3.3～4.0 (10≤N≤16)．In the processing of folding,the change of energy is fast in the beginning of folding,slow in the middle of floding and also fast in the end of folding of proteins．
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发布时间：2021-03-19 - 摘要：Novel α-cellulose membranes were prepared by using amine oxides as solvent．The mechanical performance,liquid permeation rates and the chemical resistance of the membranes were investigated．The tensile strength of the α-cellulose membranes can be up to 133.3 Mpa and 30％～60％ stronger than the cellulose membranes prepared from other methods．The retentate ratio of bovine serum albumin of the α-cellulose membranes can be up to 98％,and the liquid flux of the membranes can keep constant in a rather large pH range from pH1 to pH9．The effect of membrane preparation process on the performances of α-cellulose membrane was also revealed by comparatively studying the performances of other cellulose membranes which using different methods prepared．
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发布时间：2021-03-19 - 摘要：The blend films based on cellulose and chitin were prepared by solution casting 6％ (wt) NaOH/4 wt％ urea as a new solvent system for cellulose,which is a novel way to prepare the chitin film from the alkali solution．The structure and morphology of the blend films were investigated by infrared spectroscopy(IR),X-ray diffraction(X-RD) and scanning electron microscope(SEM),respectively．The interaction and properties in the blend films were further discussed．IR results suggested that the strong effect due to hydrogen bonding resulted in the changes of crystalline structure because of the addition of chitin,which was also confirmed by X-RD test．Such interaction directly affected the blend miscibility．When the content of chitin lower than 40 wt％ the blend films exhibited a good miscibility at a molecular scale,and or else the microphase separation occurred．The tensile test sbowed that introduction of chitin with moderate content call effectively enhance the tensile strength (σb) of the blend films．Furthermore,the blend film containing the 10 wt％ of chitin content exhibited 89.1 MPa of σb,dry and 43.7 MPa of σb,wet respectively,which were enhanced by 6.7％ and 11.5％ compared to that of the cellulose film．However,the increase of chitin content resulted in the decrease of water resistivity (R) of the blend films,suggesting that the coarse structure due to the microphase separated structure makes the water easily interpenetrate into the blend films．Simultaneously the introducing of chitin can effectively lower the adhesion,agglomeration and denaturalization of palate,namely enhance the blood anticoagulant index of the blend film．The results showed that the blend films with the chitin content higher than 50 wt％ exhibited the best blood anticoagulant activity．This kind of blend film is promising in the field of medical materials．
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发布时间：2021-03-19 - 摘要：A fume silica-supportad poly-4-oxa-6,7-dimethylselenoheptylsiloxane palladium complex has been prepared from 4-oxa-6,7-dichloroheptyltrimethoxysilane via immobilization on fume silica,followed by reacting with sodium methylselenolate and then the reaction with palladium chloride．The X-ray photoelectron spectroscopy(XPS) has been used to characterize the palladium complex and a possible structure pattern of the polymeric palladium complex has been suggested．The title complex exhibits good catalytic activity in Heck carbonylation of aryl halides with aniline or butyl alcohol under atmospheric pressure of carbon monoxide．When aryl iodides are used as the substrates,the substituted N-phenylbenzamides or butyl benzoates are obtained in good to high yields．This polymeric bidentate selenide palladium catalyst can be recovered and reused without serious loss of activity．Hence this paper presents a simple and practical synthetic method for the substituted N-phenylbenzamides and butyl benzoates．
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发布时间：2021-03-19
Research Article
- 摘要：Biocompatibility,particularly blood compatibility is the most important property required for biomedical materials．The improvement of blood compatibility is always all important research task for biomaterial research and development．It is an important way to develop biomaterials by constructing special molecules onto the proper mechanical material surface．Polyetherurethanes are widely used as biomaterials due to their good biocompotibility and mechanical properties．Nevertheless,their blood compatibility is still not adequate for the more demanding applications．The purpose of present study was to synthesis a novel nonthrombogenic biomaterial by modifying the surface of polyetherurethane．Ozone was used to introduce active peroxide groups onto polyetherurethane surface and graft polymerization of N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl) ammonium (DMMSA),asulfobetaine structure,onto the ozone activated polyetherurethane surface was conducted．The nonthrombogenic properties of grafted film were also studied．The grafted film was characterized by ATR-FTIR,XPS and contact angle measurement．The ATR-FTIR,XPS of the grafted PU film indicated that the graft polymerization did take place,the grafted PU film surface was covered with the DMMSA polymer．The grafting yields in different condition were studied．The grafting yields increased with the increase of the monomer concentration．Water absorption and contact angle showed that the hydrophilicity of the film had been improved greatly,and the hydrophilicity of the film increased with the grafting yield．The blood compatibility of the grafted films was evaluated by platelet adhesion in platelet rich plasma and scanning electron microscopy observation using PU film as the reference．No platelet adhesion was observed for the grafted films incubated for 60 min and 180 min,however,the ungrafted PU film was covered with platelet．The result of platelet adhesion experiment indicated that the PDMMSA chains could prevent platelet adhesion．That means this new material is expected to have potential biomedical applications．
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发布时间：2021-03-19 - 摘要：In order to solve the methanol crossover problem caused by the poor alcohol rejecting ability of the NafionTM membranes currently used in direct methanol fuel cell (DMFC),polyvinylidene fluoride(PVDF) was blended with Nafion material to prepare a new type of membrane for DMFC and its ionic conductivity and the methanol permeability was investigated．PVDF was used here to regulate the ratio between hydrophilic group and the hydrophobic group exist in the blend membranes according to the hydrophilic-hydrophobic balance theory proposed in pervaporation．The adding of PVDF lead to a great improvement of the membrane’s MeOH rejection．When PVDF content was increased from 25％ to 75％,the MeOH permeability was reduced from～10-7 to ～ 10-9 cm2／s,1 to 3 orders of magnitude lower than that of Nafion117．The membrane conductivity decreased,although remaining at high value( ～ 10-4 S／cm),with the increase of PVDF content．Compared with the Nafion117 membrane,the PVDF-Nafion blend membrane with only 25％ of Nafion showed an improvement in performance hy about 40 times,if the ratio(σ／P) was adopted to characterize the performance of a membrane for DMFC．Percolation theory,cocontinuous morphology features and phase transition model were applied to explain the behavior of membrane conduction．
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发布时间：2021-03-19 -
THE SYNTHESIS AND PROPERTIES OF POLYAMIDEIMIDES CONTAINING PHENYL-SUBSTITUTED PHTHALAZINONE MOIETIES
摘要：A novel diamine 2H-(4-aminophenyl)-4-(3-phenyl-4-aminophenoxy)-2,3-phthalazin-1-one (1) containing N—C coupling bond was synthesized and reacted with four aryl diimide-dicarboxylic acids to prepare a series of new aromatic poly(amide imide)s via direct polycondensation using Yamazaki phosphorylation procedure．The polymers obtained in high yield had high molecular weight with the inherent viscosity in the range of 0.50～0.70 dLg-1．Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) indicated that the polymers had high glass transition temperature of 317～343℃ and good thermostability with 10％ weight loss temperature above 440℃．They were readily soluble in polar solvents such as NMP、DMF and m-cresol etc and clear,tough,flexible films can be cast from their DMAc solutions．The structure of monomer and their polymers was characterized by MS、FT-IR and 1H-NMR and they are consistant with the proposed structure．X-ray diffraction showed that all poly(amide imide)s were amorphous．- 34
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发布时间：2021-03-19 - 摘要：Self-assembly of an amphiphilic diblock copolymer polysyrene-b-polyvinylbenzoic acid in ethanol,which is a selective solvent for the polybenzoic acid segment was studied by means of transmission electron microscopy．The diblock copolymers can self-assemble into nano scale aggregates with polystyrene segment as the core and polyvinylbenzoic acid segment as the corona．The morphology of the aggregates is mainly controlled by the ratio of the two segment of the diblock copolymer．As the content of the ethanol-insoluble polystyrene segment increased,the morphology can be changed from spheres to rods．The diameter of the aggregates increases slightly with concentration and decreases with the addition of CoCl2 salt．
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发布时间：2021-03-19 - 摘要：To achieve well-defined amphiphilic C60-containing macromolecules,C60-conjugated polystyrene(C60-PS) was first synthesized via tandem atom transfer-radical polymerization(ATRP)．With the help of tetrabutylammonium bromide(TBAB),taurine(2-aminoethanesulfonic acid) can be carried from water phase into the phenyl chloride phase and then react with C60-PS．The final product——taurine-modified C60-conjugated polystyrene——is a novel type of highly asymmetric amphiphilic diblockcopolymers,which can form spherical crew-cut type micelles by adding water in small amounts into its tetrahydrofuran solution．UV-vis spectroscopy and trasmission electronicmicroscopy have been employed to monitor the aggregating process of these spherical micelles and observe their final morphology respectively．
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发布时间：2021-03-19
Research Bulletin
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