最新刊期
卷 ， 期 5 ， 2006
- 摘要：With the sol-gel method,the regenerated SF(silk fibroin)／nano—TiO2 composite films were prepared．Comparod to the pure silk fibroin films,the mechanical strength of these regenerated SF／nano-TiO2 composite films were increased and the loss percentage of SF／nano-TiO2 composite films in aqueous solution were decreased．By using UV,AFM and SEM,these films were characterized．The experimental results reveal that the diameter of nano—TiO particles in films was about 80nm．The nano—TiO2 particles were well dispersed in the regenerated silk fibroin．It was found that the crystal structure of the composite films changed from typical Silk I to typical Silk Ⅱ.Furthermore,the crystallinity of the composite films was obviously improved．Through the TGA,it was demonstrated that the heat transition temperature of composite films was also changed．
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发布时间：2021-03-19 - 摘要：Amphiphilic dextran bearing biotin,cholesterol and hydrazide side groups was synthesized by esterifying of dextran polyaldehyde with cholesterol 3-hemisuccinyl chloride,followed by reacting aldehyde groups with adipic dihydrazie．and then conjugating carbodiimide—activated biotin to amino groups．The resultant dextran derivates were used to co-dialyze with poly(lactic acid)(PLA)DMSO solutions against water to form PLA submicron particles with dextran derivates anchored on the surface．The morphologies of the submicron particles were observed by TEM and AFM,and the diameter and diameter distribution were measured using photon correlation spectrum.The results showed that the submicion particles were spherical in shape,and the diameters could be controlled by adjusting the ratio of the Chol-Dex-Biotin to the(PLA)．The surface structure of the submicron particles was measured by XPS and the results demonstrated the existing of the dextran derivates．By conjugating these submicron particles with transferrin through acryl hydrazone reaction and IgG via biotin—avidin mediated physical linking,respectively,PLA submicron particles bearing transferrin and IgG protein simultaneously on the surface were obtained．The conjugation of transferrin and IgG was proved by fluorescence microscope and color development reaction of antiIgG—HRP．
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发布时间：2021-03-19 - 摘要：Polyisocyanurate from IPDI was synthesized by using quaternary amine salt,N,N,N-trimethyl—N-(2-hydroxyethyl)ammonium hydroxide(TMR-3) as catalyst．The structure analysis and characterization of the product was studied by NMR(1H,13C,DEPT,13C-1H-HMBC)．The peaks at δ3．509～3．650,4．094—5．047,3．052— 3．374,3．749—3．766 of the 1H-NMR spectrum were attributed to the hydrogen proton on the 1’。carbon atom connecting with the nitrogen atom of N＝C＝O,the hydrogen proton on the 1”acarbon of the IPDI trimer,the hydrogen proton on the 10”a carbon connecting with the nitrogen atom of N＝C＝O,the hydrogen proton on the 10’a carbon of the IPDI trimer,respectively．The peaks at δ 122．07—122．41,δ 123．04～123．41 of the 13C—NMR spectra belonged to the double bonded carbon of N＝C＝O of 12"and 11"．The peaks at δ 150．06．δ 150．87—150．97 of the 13C—NMR spectra belonged to the carbon on the carbonyl group of the IPDI trimer of 11”and l2’．The peaks at δ 48．75～49．01．δ 49．07—50．78 of the 13C—NMR spectra belonged to the tertiary carbon of 1’and 1”．The peaks at δ 51．14．δ 57．18～57．20 of the 13C—NMR spectra belonged to the l0”carbon of methylene．The peaks at δ 54．70,δ 57．18～57．20 of the 13C-NMR spectra belonged to the l0’carbon of methylene．The results show the main product of IPDI self-polymerization was trimer isocyanurate．Trimefized isocyanuric and isocyanate groups were main groups in the polyisocyanurate．1D and 2D NMR can differentiate two sorts of earbonyl groups and establish the connections of all carbon and hydrogen atoms of mixed structures that originated from four different substitutions．The calculated area values of peaks demonstrated the structure characterization of the polyisocyanurate．
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发布时间：2021-03-19 - 摘要：The association and properties of multi—block eopolymers(TP)of acrylamide(AM)and acrylic acid (AA)prepared by template copolymerization in aqueous solution were studied．The results showed that the copolymers of this type exhibited a significant structure effect compared with that of similar random copolymers(CP) obtained by copolymerization in the absence of template．Decrease the pH or add Ca2+ to the copolymer solution may cause phase separation．The TEM images demonstrated that the phase separation by adding Ca2+ was due to the formation of extensive intermolecular cross-linking．With increasing the pH of the copolymer solution the solution viscosity increased first and then decreased similar with that of the homopolyacrylie acid．However the increase range of template copolymer was higher than that of homopolyacrylic acid．TEM images indicated that at the maximal viscosity the template copolymer exhibited coiled aggregates．
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发布时间：2021-03-19 - 摘要：A poly(vinyl alcohol)hydrogel was prepared by coupling puly(vinyl alcohol)with epichlorohydrin as cross—linking agent．The structure of the hydrogel was characterized by FTIR and GPC techniques．Various amounts of water were added into the dry gel to swell it and the quantity of water in various states in the partially swollen hydrngel were determined by differential scanning calorimeter technique．The analytical results indicate that the water introduced into the dry gel first combines with the hydrophilie groups of the network chains through hydrogen bond forming non—freezable water．The ratio of the non—freezable water to dry gel in the hydrogels is about 0．20．After the non—freezable water is saturated,the additional water penetrates into the network space and forms simultaneously both in the freezable and free water states until reaching equilibrium swelling．
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发布时间：2021-03-19 - 摘要：Numerical simulation of the extrusion process of polystyrene in a intermeshing co-rotating twin screw extruder was carried out to compute the residence time distribution(RTD)of the material particles and other flow field parameters in various processing conditions．The computed RTD was compared witll the on-line measurement results,and a fairly good agreement was reached between them．Moreover,based on the numerical results,a definite relationship was determined for the influence of the screw rotation speed and feed rate on the residence time of the polymer melt．Numeric simulation results also predicted the profile of the flow field parameters such as temperature,filling ratio,pressure and viscosity along the axis of the screw under various processing conditions．The computer simulation method helps to investigate the internal flow state and residence time of the polymeric melt in a twin screw extruder and therefore helps to optimize the production．
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发布时间：2021-03-19 - 摘要：N-(4-vinyl)benzylimidazole and its copolymer with octyl methacrylate(PBIOM)were synthesized and characterized,and oxygen—binding properties of cabaltporphyrin(CoP)complexes with imdazole ligands were studied．The weight—average molecular weight and imidazole content of PBIOM were determined to be 3．4×105 and 57 mol ％ by GPC and elemental analysis,respectively．PBIOM or benzylimidazole(BIm)and CoP in chloroform solution were mixed to complex the imidazolyl residue of the ligands with the fifth coordination site of CoP under nitrogen atmosphere to get CoP complexes．CoP complex displayed a reversible change in the UV-visible absorption spectrum from the deoxy form to the oxygen-binding one with an isosbestic point,in response to the partial oxygen pressure of the atmosphere．The oxygen-binding equilibrium curves of CoP complexes obeyed a Langmuir isotherm,to give the oxygen-binding affinity P50(oxygen partial pressure at which half of the CoP binds with oxygen)．At the same partial oxygen pressure,the oxygen—binding ratio of CoP-BIm complex was a little larger than that of CoP-PBIOM complex．The oxygen—binding affinity of CoP-PBIOM complex in the solid membrane state was larger than that in chloroform solution．The half lifetime of CoP-PBIOM membrane at 60 ℃ was 40．7 h．while that of CoP-BIm membrane(poly(octyl methacrylate) as matrix)was 8．8 h,indicating that polymer ligand significantly prolonged the lifetime of CoP complex．
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发布时间：2021-03-19 - 摘要：The friction and wear behaviors of calcium sulphate whiskers modified bismaleimide resin under different friction load,coupling agent,and whisker content were investigated．The resets show that the resin matrix exhibits adhesion wear under lower friction load,but it shows serious plastic distortion and crack under high friction load．The properties of composites with calcium sulphate whisker arc improved obviously．The wear rates of the composites are decreased markedty by adding calcium sulphate whiskers．When friction load increases from 200 N to 300 N,the wear of the resin matrix is changed from an adhesion wear to a fatigue one．At lower whisker contents,the wear of the composites shows adhesion features．While at higher whisker contents,it is dominated by particle wear．
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发布时间：2021-03-19 - 摘要：Poly(N-acryloxysuccinimide)(PNAS)was synthesized by atom transfer radical polymerization(ATRP) with 2-hydroxyethyl-2-bromoisobutyrate(HEBriB)／CuBr／2,2’bipyridine(bpy)as the initiation system．Its molecular weights can he predicted from the molar ratio of NAS／HEBriB in feed and the conversion．N-oxysuccinimide(NS)groups in PNAS are very active,and can be easily substituted by anmino compounds,such as butylamine,etc．So PNAS is used as precursor in preparation of conductive polymers．The polyaerylimide containing tetraaniline(PAA-NH(PhNH)3Ph)was successively prepared by the reaction of PNAS with amine capped tetraaniline(NH2(PhNH)3Ph)at 50℃ for 24 h．The substitution reaction efficiency is determined by the reaction temperature and the feed ratio of NS units to amine capped tetraaniline．When the substitution reaction was carried out at 50℃ with a molar ratio of NS／tetranniline 1：3．1H-NMR and FT-IR spectra of the product showed that the NS units in PNAS were substituted almost completely．While,only 10％ NS Was substituted at room temperature using the same feed ratio．The cyclic voltammetry measurements of the product showed two oxidation peaks at 0．4 and 0．62V．This provides a new routeto synthesize conductive polymers with aniline oligomers as side chains．
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发布时间：2021-03-19 - 摘要：A series low band—gap conjugated copelymers(PFO—DTP)derived from 9,9-dioctylfluorene(DOF)and 5,7-dithien-2-ylthieno[3,4-b]pyrazine(DTP)is prepared by the palladium—catalyzed Suzuki coupling reaction with the feed ratios of DTP mole percents around 1％,5％,15％,30％．The resulted pdymeers are soluble in common organic solvents．There are two absorbance peak around 380 nm and 632 nm in the spectra of copolymem．The absorbanee peak around 632 nm increased as the DTP contents increased．Maximum external quantum efficiency reaches 0．1％in devices of copolymers with the DTP content at 5 mol％．In comparison with its very well studied isomer copolymer poly(2,7-(9,9-dioctyl-fluorene)-co-4,7-di-2-thienyl-2’,1’,3'-benzothiadiazole),the pdy(2,7-(9,9-dioctylfluorene)-co-5,7-dithien-2-ylthieno[3,4-b]pyrazine)(PFO—DTP)shows a red shift of about 110 nm for photoluminescence(PL)and electroluminescence(EL)emissions,and the optical onset wavelength of the PFO—DTP is red shifted about 130 nm and their optical response is more matching the optical spectra of the solar terrestrial radiation．These copolymers are promising candidate materials for near-infrared light—emitting diodes and polymeric photovoltaic solar cell．
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发布时间：2021-03-19
Research Article
- 摘要：A water soluble hydroxy-capped comb—like poly(ethylene glycol)(CPEG)was prepared via atom transfer radical polymerization(ATRP)．A stable CPEG coating was obtained via dip-coating followed by curing at 70℃ for 48 h．The CPEG-modified surface W85 proved to be stable in both aqueous environment and ambient according to contact angle behavior and weight deecrement testing．The coating forming mechanism was investigated through FTIR．the spectra data demonstrated the stability of CPEG coating derived from its hydrogen bend of inter-molecules and intra—molecules．Platelet experiment showed CPEG modified surface reacted extremely weakly with platelet and showed excellent thrombus resistance than that of both on the pure PET surface and PET surface modified with linear PEG．The model drug RD6G was applied to fabricate a drug-buried CPEG coating surface．The drug-releasing curve demonstrated the stability of the CPEG coating and the controlled-release ehavior of RD6G．The unique property of CPEG coating surface provided the potential application in the immobilization and release of aqueous drug,including protein and peptide．
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发布时间：2021-03-19 - 摘要：A carbosilane dendrimer based macrophotoinitiator(MPI-185)containing benzophenone moiety terminal groups was synthesized by a divergent bydrosilylation／allylation reaction sequence followed by alcoholysis of the silicon chloride end groups．The structure of MPI-185 was characterized by FTIR,1H-NMR,13C—NMR,and29Si—NMR,and its intrinsic viscosity,molecular weisht and polydispersity were meassured on by using a GPC complex system．Its reactivity was tested via curing a sensitive epoxy acrylate(EA)resin using FTIR,and the thermal preperty of films cured was measured by TGA．The results were compared with those of a small molecule photoinitiator(185)．It Was found that the cutting efficiency of macrophoinitiator(MPI-185)was satisfactory,and the thermal degradation temperature of EA resin eared with MPI-185 was also markedly improved．
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发布时间：2021-03-19 - 摘要：The synthesis and characterization of a series of peptide dendronswith glycin(Gly)and glutamate(Glu) as building blocks were described．The dendrons were prepared with convergent method by protection．deprotection and DCC coupling reactions．With the characterization of elemental analysis,1H-NMR,13C—NMR,FTIR,EI-MS and MAILD—TOF MS,the designed molecular structure was proved．It could be predicted that the obtained compounds will exhibit unique properties and potential applications in the fields of biology,medicine and so on．Further studies on the properties of these compounds are in progress．
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发布时间：2021-03-19 - 摘要：The damage effect of methyl silicone rubber reinforced with MQ—type silicone resin which composed of monc-functional silicon—oxygen unit and tetra-functional silicon-oxygen unit under 150 keV proton radiation was studied using space combined radiation simulator．The experimental results show that there were aging cracks appearing on the surface of the rubber after irradiation．With a lower irradiation fluence(14cm-2),the hardness and tensile strength of the rubber increase；the elongation at break decreases；the storage modulus at lower temperatures increases；the glass—transition temperature moves to higher temperature band,the Si--O content increases；the main damage of the silicone rubber is caused by the erosslinking effect．While with a higher irradiation fluence(>1014cm-2),the hardness and tensile strength of the rubber decrease．the dongation at break increases,the storage modulus at lower temperatures decreases．the glass—transition temperature moves to lower temperature band．the Si-O content decreases．the main damage of the silicone rubber is caused by the degradation effect．A mass loss of the silicone robber can be caused by the proton irradiation because the volatile substances generated by the degradation of silicone rubber subjected to proton irradiation can be extracted in the high vacuum environment.
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发布时间：2021-03-19 - 摘要：Silver-poly(4-vinylpyridine)(Ag-P4VP)hybrid microgels were synthesized by γ-irradiation and surfactant-free emulsion polymerization in a single step．The effects of dose rate and the concentrations of isopropanol,silver ion,N,N’-methylenebisacrylamide(Bis)and 4-vinylpyridine(4-VP)on the hybrid micmgels were studied in detail via transmission electron microscopy(TEM),powder X—ray diffraction(XRD) or dynamic light scattering(DIS)．The results indicated that the size of Ag nanoparticles in the hybrid microgels increased with the increase of Ag+ or Bis concentration and with the decrease of dose rate or isopropanol concentration．When the dose rate Was decreased,the phase state of AS nanoparticles was gradually transformed from amorphous state to cubic crystalline state．Although the variety of the P4VP microgels’size was more coinplex,it could also be easily adjusted by the above—mentioned conditions．
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发布时间：2021-03-19 - 摘要：The curing process of dendritic polymer PAMAM with his—phenol A epoxy resin was investigated using isothermal differential scanning calorimetry(DSC),the mechanism of this reaction was autocatalytic．The data of two reaction rate constants kl,k2 and reaction orders m,n were obtained from Kamal equation．The overall reaction order m+n was between 2．07 and 2．29,the apparent activation energies of E1 and E2 were 59．79 kJ／mol and 56．51 kJ／mol．respectively．The reaction entered into a diffusion controlled stage at the conversion of 50％,experimental data and theoretic curve had deviation at this time．The reaction conversion,at which the deviation occurred,decreased with lowering curing temperature．
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发布时间：2021-03-19 - 摘要：Polymeric micelles were prepared by dropping ethanol into solutions containing poly(γ—benzyl L—glutamate)-poly(ethylene oxide)block copolymer(PBLG-b—PEO),chloroform(CHCl3)and trifluoroacetie acid (TFA)．Viscometry,transmission electron microscopy(TEM),nuclear magnetic resonance(1H-NMR)spectroscopy and infra-red difference spectroscopy(IR)were used to investigate the influence of PBLG chain conformation on the self-assembly behavior of PBLG-b-PEO．The experimental resuhs revealed that PBLG—b—PEO could associate into polymeric micelles in ethanol solutions．The introduction of TFA not only changes the conformation of PBLG segments,but also increases the critical micelle concentration,and further affects the morphologies of the formed micelles.
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发布时间：2021-03-19 - 摘要：A kind of supramolecular building unit,2,6-di[N-(carboxyethyl carbonyl)amino]pyridine(defined as DAP)was synthesized from 2,6-diaminopyridine and succinic anhydride by a simple procedure．The structure of DAP was confirmed by 1H—NMR,IR and elemental analysis．Supramolecular hydrogels were formed during the cooling of DAP aqueous solutions at a concentration range of 3 wt％～10 wt％．As observed by scanning electron micrescopy,supramolecular fibers were noticed in the bytes and their dimensions can be regulated by the concentration of DAP．At higher concentrations of DAP,larger fibers and lower hydrogel strengths were resulted．Based on the formation of hydrogen bonds of the molecules an assembling process for supramolecular hydrogels was proposed．
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发布时间：2021-03-19 - 摘要：A method was developed to synthesize amphiphilic poly(ε-caprolactone)-b—poly(ethylene glycol)(PCL—b-PEO)block copolymers with well—defined structure and with functional antino end-group connected to the PEO block．The molecular weight,composition and chain structure of the resultant copolymers were characterized by GPC and 1H—NMR．The microspheres of the copelymers were prepared by W／O／W double emulsion solvent evaporation method．The analysis results by confocal laser scanning microscopy indicate that the anlino groups are distributed dominantly on the surface of microspheres due to the hydrophilic property of amino groups and the formation process of microspheres in aqueous phase．The surface morphology of microspheres could he regulated by changing the composition of block copolymers．The results of this work indicate that the surface properties of the miemspheres can be controlled by polymer chain structure,and that the microsoheres with amino group located on the surface can be further conjugated with peptide such as RGD．Therefore,these microspheres are promising materials as microcarriers for promoting cell growth．
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发布时间：2021-03-19
Research Bulletin
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