最新刊期
卷 ， 期 3 ， 2004
- 摘要：Eu(DBM)3·H2O nanocrystallites were obtained by the chemical precipitation method．By the elemental analyzer．irfrared spectrum,TGA-DSC and TEM,that the construction of nanocrystallines,the thermal properties and size were confirmed,in addition,fluorescence excitation and emission spectrum,ultraviolet absorption spectrums were investigation．Then the nanocrystallines were incorporated into the copolymer system of styrene and methyl acrylic acid．the fluorescence functional polymer nanometer materlal with high lanthanide content (50wt％) were obtained．The experiment indicated that Eu (DBM)3·H2O nanocrystallines particle sizes were in 30～300 nm,it exhibited eumpium ion ehar|atanistie luminescence．The optical resins could provide a rdativdy stable environment for Eu (DBM)3·H2O nanocrystallines．
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发布时间：2021-03-19 - 摘要：Discrete nano-aggregates of a poly(ethylene oxide)-b-polybutadiene diblock copolymer(PEO-b-PB)were obtmned by self-assembling of the copolymer in a selective solvent of PB followed by the shell cross-linking．The average behaviors of the PEO crystallization and melting confined within the nano-structured aggregates were studied by differential scanning calorimetry experiments The experiments demonstrated that the confinement effect arisen from the shells could be tuned by adjusting the degree of PB cross-linking．For the deeply cross-linked sample,the individual paaicles only crystallized at very low crystallization temperature(Tc),wherein the homogenous primary nucleation determined the crystallization rate．For the lightly cross-linked sample,the confinement effect is Tc dependent．When Tc exceeded 42℃,the lighfly cross-linked sample possessed a higher melting temperature and a lower crystallinity compared with the pure PEO-b-PB.
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发布时间：2021-03-19
Rapid Communications
- 摘要：A novel soluble photosensitive azo polyimide was synthesized from 4,4'-di(1,2-anhydride-4-carboxylate) azobenzene and 4,4'-diamino-4″-hexadecyloxy triphenylmethane through a polyimidization reaction The structure and properties of the obtained pelyimide weTe characterized by using 1H-NMHDSC．FrnR and UV-Vis spectroscopy The polymer showed significant photochromic effect upon UV irradiation due to the cis-trails photoisomerization．It was observed that the thin films of the polymer,after being irradiated with linearly polarized UV light and assembled in LC cells as alignment Lavers,coilld induee uniaxial homogenous orientation of nematic LC molecules．
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发布时间：2021-03-19 -
STUDY ON THERMO-SENSITIVE AMPHIPHILIC COPOLYMERS FROM N-ISOPROPYLACRYLAMIDE AND CHOLESTERYL ACRYLATE
摘要：The copolymers of N-isopropylacrylamide(NIPAM) and cholesteryl acrylate (CHA) in different molar ratios were synthesized and characterized．The surface activity and micellar behavior of the copolymers in aqueous solution were studied by surface tension method and fluorescence probe method．The Lower Critical Solution Temperature (LCST) of the copolymers was determined by fluorescence probe and turbidity measurement method Results showed that the incorporation of hydrophobic comonomer CHA led to a lower LCST than PNIPAM and the LCST decreased with the increase of the ratio of CHA．The copolymers in aqueous solution had obvious aggregation behavior with the increase of their concentrations It was evident that the introduction of a small amount of CHA units into the polymer backbone could lead to a very dramatic effect on the amphiphilic properties of the copolymers．The inner core of the micelles formed by self-aggregates of CHA segments of the copolymers was observed to encapsulate hydrophobic compounds,such as cholesterol(a drug model)．With the increase of cholesterol amount in the sample solutions with the same polymeric concentrations,the average size of the formed micelles shifted to a larger value, which indicated that more cholesteml molecules were encapsulated in the micelles．- 32
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发布时间：2021-03-19 - 摘要：Some Ni (Ⅱ) salicyladimine complexes are neutral single component polymerization catalysts which can tolerate many functional groups．They can catalyze polymerization of olefins even olefins with polar groups The catalytic polymerization mechanism was modeled by the reaction of ethylene with (NH=CH—CH=CH—O) NiCH3R The neutral reaction mechanism and the cationic reaction mechanism of ethylene polymerization were studied based on DFT method at B3LYP,LANL2MB level．The result shows that the insertion is initiated by the complexation of the incoming ethylene with the electron-deficient metal center to form a π-complex．This complexation assists the insertion of the ethylene into the metal-carbon bond via a four member cyclic transition state．After insertion,a product with γ-agostic interaction is formed．Finally,a product is formed with the β-agostic interaction species resembling the starting material,so a new vacant coordination site is available for the next ethylene to coordinate and propagate the chain．Moreover,the calculation results indicate that the neutral reaction mechanism is similar with the cationic reaction mecanism．Compared with the cationic reaction mechanism,the neutral reaction mechanism is easier to initialize．By comparing,it is shown that the interaction of ethylene with the cationic active center is stronger than that with the neutral active center The activation energy for the cationic mechanism is lower than that for the neutral mechanism It implies that the process of the cationic reaction mechanism is easier than that of the neutral mechanism．The β-agostic action plays an important role in the neutral catalytic reaction mechanism,and it dominants the Ni charges in the alkyl complexes．
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发布时间：2021-03-19 - 摘要：The thixotropic experiments were carried out for a LDPE (PE-FSB-23DO22/Q200) melt．The results show that the LDPE melt has complex time-dependent viscoelastic properties. The stress geowth experiments show further that the shear stresS will descend with the development of time at a constant shear rate of 5 s-1．A transformation of Huang equation was used to describe the thixotropy loop,and the calculated values agree well with the experiment results．At the same time,it is noted that the parameters of the transformed Huang equation m not universal and cannot be used to characterize completely the viscoelastic properties of the LDPE melt．The stress relaxation after cessation of steady shear cannot be described by the transformed Huang equation．
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发布时间：2021-03-19 - 摘要：Synthesis,characterization and nonlinear optical properties of isocyanate crosslinked epoxy-based second—order nonlinear optical (NLO) polymers were studied in this paper．The epoxy-based second-order NLO polymer (BPAN-lA-NT) was synthesized through the coupling reaction between p-nitrophenyl diazonium salt and an epoxy-based precursor polymer,which was prepared by the polycondensation of diglycidyl ether of bisphenol-A and aniline Bi-component (BPAN-lA-NT/M2OS) thin films were prepared by spin-coating from the solution of BPAN-lA-NT mixed with certain amount of a cross linking agent M2OS (MDI based isocyanate)．The epoxy-based second-order NLO polymer BPAN-lA-NT could be crosslinked by the reaction with isocyanate during the poling process．A high second-order nonlinear optical coefficient of 105.2 pm/v at 1.064 μm was obtained for the bi-component films after corona poling．Moreover,thermal stability measurement of poled BPAN-lA-NT/M20S film showed good dipole orientation stability at high temperature,retaining above 80％ of the initial d33 value at 200℃．At the sametime for the single component BPAN-lA-NT thin film its d33 value was 33.2 pm/v only and the d33 value decreased obviously when the temperature was higher than 120℃．
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发布时间：2021-03-19 - 摘要：SiO2/vinylidine fluoride-hexnfluropropene copolymer[P(VDF-HFP)] composite porous polymer electrolytes were prepared by phase inversion induced by water vapor．The influence of nano-SiO2 on the porous structure and performance of the porous polymer electrolytes was studied．The results show that when the weight ratio of SiO2 to polymer is about 0.05,the porous polymer electrolytes have improved conductivity and interfaeial stability against lithium metal electrodes；but when the amount of SiO2 is further increased,serious aggregation of nano—SiO2 can be found in the pores,and the performance of the porous polymer electrolytes is reduced．
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发布时间：2021-03-19 - 摘要：The copolymefization of aerylamide (AM) and sodium 2-acrylamido-2-methyl-propane-sulfonate (NaAMPS) was carried in aqueous solution,and a series of copolymer P(AM-co-NaAMPS) with varied composition were prepared The structure and composition of the copolymers were characterized by FTIR spectroscopy and element analysis．The viscosities of the copolymers were determined using an Ubbelohde viscometer,and the intrinsic viscosities by which molecular weight can be calculated were determined with the method of extiapolation to zeio concentration At the same time the Huggins constants by which the interaction between polymer and solvent can be displayed were also obtained．The apparent viscosities of aqueous solutions and brine of the copolymers were measured using a low shear rotational viscometer．Thermal stability experiments were carried out formeasufing the maintaining ratios of viscosity at high temperatures．In this work,the relationships between the structare and composition and the properties of the copolymers P(AM-co-NaAMPS) were studied．The experimental result shows that the properties of the copolymers P(AM-co-NaAMPS) depend strongly on their structure and compositions,and incorporation of the NaAMPS segments in polymer backbone of PAM results in excellent properties of the copolymers,such as better solubility,better thickening ability,improved resistance to temperature and improved salt tolerance due to the strong anionic property of sulfonate groups and sterlc hindrance of great side groups．These properties are significant in enhanced oil recovery．The molecular weisat of the copolymers is influenced by their composition and the polymerization process At the same time,the molecular weight is also an important parameter influencing the properties of the eopolymer．The experimental results indicate that the properties of the copolymer vary regularly with its structure and composition．
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发布时间：2021-03-19 - 摘要：The polypropylene (PP)/organic rectofite (OREC) nanocomposites were pmpamd by extruding the mixtures of OREC and PP using a twin-screw extruder The crystallization behavior of PP and PWOREC nanocompesites was studied by wide angle X-my diffraction analysis (WAXD) performed at angle range of 10～25°and differential scanning ealofimetry (DSC) conducted at constant coolingrate of 2.5 K/min,5K/rain,10K/minand 15 K/rain,respectively．The results of WAXD analysis show that the introduction of OREC does not change the crstal form of PP in the compecites．Non-isothermal crystallization kinetics of PP and PP/OREC nanocompesites WaS investigated by means of DSC．and the data are successfully analyzed by the Jeziomy and the Mo Zhishen methods．The non-isothermal crystallization kinetics parameter(Zc) and Avmmi exponent (n) for PP and PP/OREC nanocompesites were reduced with cooling rate increasing．However,for PP/OREC nanocompesites,they are higher than those of PP at the same cooling rate．The characteristic cooling rate,F(T),increases with the degree of crystallinity for both PP and PP/OREC nanocompesites,but the values of F(T) of PP/OREC nanocompesites were lower than those of PP at the same degree of crystallinity All the above analyse indicate that particles of OREC have heterogeneous nucleation effects on PP matrix．
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发布时间：2021-03-19 - 摘要：The polysiloxane/acrylates copolymer latex with core-shell structure was prepared in the semi-batch emulsion polymerization of methyl methacrylate (MMA) in the presence of polysiloxane latex as seeds．The polysiloxane seeded latex was polymerized by octamethyleyclotetrasiloxane (D4) and vinyl methylcyclotetrasiloxane (ViMeSiO)4,and methyl triethoxysilane (MTES) as the crosslinking reagent．The effects of polymerization methods and preparation conditions (the concentrations of emulsifier and initiator,the adding mode and rate of MMA) on the average particle size,and its distribution,and the morphology of the obtained particles were studied．In comparison with batch process,the semi-batch process by adding MMA is more preferable for preparing a stable copolymer latex with smaller particle size and narrower distribution．The higher concentration of emulsifier and initiator will cause smaller particle size and narrower particle size distribution,the foster adding rate of MMA will cause smaller particle size,but wider particle size distribution．The TEM photos show that the composite particles prepared in the semi-batch process by adding MMA monomers have clear core/shell structure,but particles by batch method have irregular shape and no such structure．Besides the micelle nucleation during the seeded emulsion polymerization,the homogeneous nucleation cai't be neglected because of the slight solubility of MMA in water．Under lower concentration of emulsifier and slower adding rate of MMA,the polymerization of shell monomers will be restricted in the“transition area” on the surface of the polysiloxane seeds．The particle size,distribution and morphology of the composite particles can be controlled by changing the concentration of the emulsifier and the adding rate of MMA．
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发布时间：2021-03-19 - 摘要：A series of polyether-urethane-imide(PUI)/silica(SiO2) hybrid composite materials with different silica content were successfully prepared by the Sol-Gel process．The properties of in-situ synthesized PUI/SiO2 hybrid materials weFe characterized by NMR,FTIR．SEM,DSC and TG measurements．The FTIR analysis revealed that the reaction of imidization of PUI in the organic phase and the reaction of SiO2 sol-gel transformation in the inorganic phase are simultaneously completed in this system at 100℃ The TG and the SEM results indicated that PUI/SiO2 composite materials with appropriate silica contents (approximately 9 wt％) possessed outstanding thermal stability,in these cases silica particles with diameters around 0.2～1.0μm were observed．The result showed that with increasing silica content the silica particles grew larger,resulting in obvious separation of the organic and inorganic phases The DSC results suggest that Tg of the soft segment rich phase of PUI/SiO2 hybrid materials is not Influenced obviously by introducing SiO2 to PUI systems．
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发布时间：2021-03-19 - 摘要：A series of chitosans with different molecular weight were first prepamd by chemical degradation．They were then used to synthesize N-suecinyl-chitosans(SUC-CS) labeled with a fluorescein FITC. They were incubated with K562 leukemia cells for affinity test．Fluorescence intensity of cells was determined by flow cytometry to assess the affinity of N-succinyl-chitosans for K562 leukemia cells．The results showed that the affinity of N-succinyl-chitosans for K562 leukemia cells was strong and declined with increasing their molecular weight．providing primary data of SUC-CS as targeting cartier of anti-tumor drugs．
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发布时间：2021-03-19 - 摘要：A series of biseyclopentadienyl tetraearbonyl di-iron complexes,[cp’Fe(CO)2]2(Cp’=C5H5,C9H7, C5HMe4,Me3SiC5,C5HPh4,t-BuC5H4),were employedforthe radical polymerization of styreneintoluene using Me2CBrCO2Et as initiator．It was found that the polymerization was uncontrollable for systems of [C5H5Fe(CO)2]2 and[C9H7Fe(CO)2]2．When the bulky substituents were introduced to the cyclopentadienyl rings,the polymerization rates became much slower When [C5HPh,Fe(CO)2]2 was used to catalyze the bulk polymerization of styrene,although the molecular weight distribution was somewhat broad,the molecular weisht Mn increased linearly with the converisou rate and the measured Mn values were very close to the thoretical values,indicating that the molecularweight is controllable．For the system of [(t-BuC5H4)Fe(CO)2]2,the molecular weight Mn increased linearly with the converison rate and the molecular weight distribution decreased with convemion increasing,indicating the polymerization system is controllable.
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发布时间：2021-03-19 - 摘要：The effect of solid fillers [(Al,cyclotetramethylene tetranitramine (HMX),ammonium perchlorate (AP)] on the crystallization behavior of PEG was studied by using DSC and WAXD techniques．AI and HMX have no effect on the crystallinity and crystal structure of PEG in composites There is a strong interaction between AP and PEG,which decreases the erystallinity of PEG in the mixtures．Some other metal salts have shown the same strong influence on the crystallization of PEG like AP It was found that they all are soluble in PEG melt．The decrease of crystallinity of PEG in the presence of AP and other metal salts is attributed to the formation of complex between the metal cations and the oxygen atoms of PEG molecules,which prevents the crystallization of PEG molecules in the composites．
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发布时间：2021-03-19 - 摘要：A fluorinated polypyrrolone (Pry) derived from a new aromatic tetraamlne,2,6-bis(3’,4’- diaminophenyl)-4-[3”,5″-bis (trifluoromethylphenyl)] pyridine (6FPA),which was synthesized by the Chiehibabin’sreaction,and the aromatic dianhydride ODPA by a two-step polyeondensation procedure was synthesized and characterized The flexible and tough films prepared by casting from the precursor solutions PAAA．followed by thermal dehydrating,showed good thermal stability with thermal decomposition temperature of 544℃,10％ weight loss temperature of 591℃,glass transition temperature of 318℃ and weight retention ratio of 68％ at 720℃．The PPy films exhibited exceflent alkaline-aqueous-repellent properties and retained most of the properties even after boiling in 10％ NaOH solutions for seven days,which made it a good candidate for protecting coating applications．
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发布时间：2021-03-19 - 摘要：Polystyrene (PS) was obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization,using benzyl dithiobenzoate,(PhC(S) SCHPh),as transfer agent,AIBN as initiator．A amphiphilic copolymer,P(styrene-b-4-vinyl pyridine)(PS-b-P4VP) was prepared by using PS as macro-chain transfer agent and AIBN as initiator via the RAFT mechartism．Its strdcture was obtained by 1H-NMR analysis The conversion can reach almost 95％ within 24 h．Its structure was characterized by 1H-NMR studies The results showed that the molecular weight of the copolymer increased lineady with the increasing of conversion,and the living nature of the polymerization was revealed Self-assembly of this amphiphilic block eopolymer in different selective solvents was also studied by using transmission electron microscopy (TEM) and scanning electron microscopy(SEM)．The results showed that core shell microspheres were formed with P4VP block as the core and PS block as the shell in the nitrobenzene/THF solvent．The size of particles increased with the increasing of the concentration of the block copolymer．The size and shape of the panicles were also changed with the type of the solvent and concentration．
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发布时间：2021-03-19 - 摘要：MgCl2-SiO2 supported monocyelopentadienyl titanium complex containing β-diketone ligand catalyst,CpTi(dbm)Cl2/MgCl2-SiO2/MAO,was prepared and the effect of the content of this supported catalyst on catalytic activity was investigated The activity is greatly influenced by the content of Ti,Mg and SiO2 The activity of the catalyst cab be improved by adding SiO2 with good flowability and treating MgCl2-SiO2 with MAO,and the influence of Mg on the activity of Ti is also important for improving the catalytic activity．Another supported catalyst．CpTi-(dbm)Cl2/MgCl2-ZnCl2-SiO2/MAO,whereas SiO2 was treated by MAO and ZnCl2 previously,was prepared and its catalysis for ethylene polymerization was investigated The activity increases with increasing the ZnCl2 in feed,while the molecular weight of polymers decreases and the molecular weight distribution broadens．
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发布时间：2021-03-19 - 摘要：Highly cross-linked and narrow dispersed pely(divinylbenzene)(PDVB) mierospheres were prepared by the dispersion polymerization of commerical divinylbenzene using aeetonitrile as solvent in the presence of 2,2’-azobis(2-methylpropionitrile) (AIBN) initiator and polyvinylpyrrolidone (PVP) stablizer．The particle average diameter and the particle size distribution were determined by SEM Narrow dispersed microspheres with diameters between 3 and 5μm depending on the conditions were produced．The effects of concentrations of initiator and stabilizer,solvent variety,ratio of monomer and solvent on particle average diameters and particle size distributions were investigated．Based on an optimal cedition,larger particle size and narrower dispersed microspheres can be synthesized,the particle average diameter is 3．95μm and the coefficient of particle size distributions (PSD) is 0.106. The time dependence of stabilizer (PVP) content,residual double-bonds and the relative ratio of para-and meta-divinylbenzene in the microspheres were studied by IR psectra．The ratios of characteristic absorbance of components changing with time showed the change of each component in the polymerization product．Monomer conversion was determined gravimetrically after washing residual monomers from the raw particle slurries and drying under vacuum．It is revealed from the conversion-time curve that the polymerization reaction is almost complete in 12 h. The content of residual double-bonds in the microspheres was determined by the reaction with Br2/H2O,then titrated by 0.1 mol/L criterion NaOH solution．The miemspheres produced by dispersion polymerization as mentioned above contmn(1.7±0.5)mol／g residual double-bonds The thermostability of microspheres were determined by TG．The starting temperature of decomposition is above 400℃,the fastest decomposing temperature is 461．6℃,showing that PDVB microspheres have high thermo-stability．
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发布时间：2021-03-19 - 摘要：Anchoring of 4,4'-azobis(4-cyanopenlanoic acid) (ACPA) onto nanometer silica and radical graft polymerization of methyl methacrylate (MMA) from the modified silica throush emulsion polymerization were investigated．The anchoring of ACPA onto silica was achieved by treating of silica with glycidoxypropyl-trimethoxysilane and reacting with ACPA．The anchoring of ACPA was confirmed by DSC and element analysis．Poly (methyl methacrylate) (PMMA) was effectively grafted onto nanometer silica throughe initiation of anchored ACPA during emulsion polymerization．The grafting percentnge and efficiency of PMMA were 23.2％ and 36.1％ determined by TGA．Furthermore,the aggregation degree of the original nanometcr silica was decreased by in-situ polymerization,and the stability of PMMA/nano-silica composite latex was good．
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发布时间：2021-03-19 - 摘要：Sodium carboxymethylcellulose/montmorillonite nanocomposites were prepared by using the solution intercalation technique．The (001) diffraction peak was not observed in the X-ray diffraction partem of the composites．TEM studies indicated that the silicates were exfoliated and distributed in the carboxymethyIcellulose matrix at the nanometer level．Infrared spectroscopy analysis revealed that the interaction between the ether oxygen atoms of the celulose molecules and the silicon-oxygen and/or the aluminum-oxygen bonds of montmorillonite might be the driving force for intercalation for the composite system The thermal stability and the tensile strength of the sodium carboxymethylcellucose nanocomposites were improved and their water vapor permeability was decreased as compared to those of the pure polymer.
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发布时间：2021-03-19 - 摘要：Polypmpylene/attapulgite nanoeompesites were prepared by melt blending The effects of attapulgite on crystallization of lop were investigated by meslls of X-ray diffraction(XRD). It was found that the(110) plane spacing of attapulgite in the composites did not expand．It implies that no intercalation phenomenon occurs in these composites．The add of attapulgite made the micmerystal dimension of polyprcpylene increase The thermal behavior of PP nanocomposites was analysized by differential scanning calorimetry (DSC),and the results showed that a proper amount of altapulgite can increase the crystallization temperature and crystallization rate of PP．and so make the erystallinity increase The spherulite morphology was observed by polarized optical microscopy (POM),and the addition of attapulgite acted as a nucleating agents for the crystallization of PP and reduced the sphemlite dimension When the content of attapulgite reached about 10 percent．no sphemlite was observed．The morphology of attapulgite particles and their dispersion in the PP matrix were analysized by scanning electron microscopy(SEM) and atomic force microscopy(AFM)．It was found that the attapulgite particles have a fibrous or rodlike morphology and almost homogeneously dispersed in the PP matrix,without preferential orientation．
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发布时间：2021-03-19
Research Article
- 摘要：Regioregular puly(1-butoxy-2,4-m-phe“ylenevinylene) was synthesized by Wittig reaction with salicylaldehyde as the starting material,and its pmperties were compared with poly(2,5-dibutoxy．1．4-p-phenylenevinylene-alter-p-phenylenevinylene) (Bu-PPV) and poly(2,5-dibutoxy-1,4-p-phenylenevinylene-alter-m-henyknevinylene) (Bu-PMPV)．The results showed that the introduction of m-phenylene could obviously improve the solubility．Thus,the solubility of Bu-PMPV was almost one order of magnitude higher than that of Bu-PPV．and Bu-MPV had a solubility 2～5 times of that of Bu-PMPV．The introduction of m-phenylene also caused obvious blue-shifts in the UV-Vis absorption and fluorescence spectra．The UV-Vis spectrum of Bu-MPV in CHCl,showed one absorption band λmax at 316 am．The fluorescence of Bu-MPV solution in CHCl3 exhibited a very narrow emissiorl peak with emission maxima at about 419 and 434 nm,the full width at half-maximum of the emission peak is about 60 nm.
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发布时间：2021-03-19 - 摘要：The nonisothermal crystallization of poly (butylene dodecanedioate) was studied by differential scanning calorimetry,crystals of polyesters were observed through polarized optical microscope,and an Avrami method was used to analyze the kinetics of nonisothermal crystallization The results showed that the crystallization temperature decreased slowly with an increase in the cooling rate．Furthermore,secondary nucleation was observed in the pmcess of PBDD nonisothermal crystallization,and the Avrami exponential values n of PBDD indicated that the mechanism of crystallization was a tridimensional growth with heterogeneous and homogeneous nucleation Meanwhile,the Avraml values n of P(BDD-co-BT)-20 is 1．which indicated that their mechanism of crystallization was a one-dimensional growth with heterogencous nucleation Crystallization activation energies implied that it is easier to crystallize for copolyester From the observed results of spherulites,it can be concluded that the size of sphemlites decreases with increasing the content of terephthalic acid.
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发布时间：2021-03-19 - 摘要：A novel polyimide (PI) containing pendent biphenyl ester groups was synthesized from 3,5- diaminobenzoic-4’-biphenyl ester (DABBE) and 3,3’,4,4'-oxydiphthalie dianhydride (ODPA) by a one-step high-temperature polycondensafion in m-cresol．This PI is a semicrystalline polymer．Lots of short fine fibrie crystals with length and diameter about 20 μm and 1 μm respectively disperse randomly in the PI film．The optical textures and the X-ray diffraction patterns of the PI solution and film show that the PI main chains arc in the extended conformation and pack parallel to each other,and the pendent biphenyl ester groups occupy the space between the main chain layers,more or less perpendicular to the main chains．At the same time,mechanical and thermally stable properties of the PI film were investigated．The exceUent mechanical properties of general polyimide films arc reasonably maintained．the polyimide film with pendent groups showes higher tensile strength and modulus and lower Tg. TGA study showes a typical two-step weight loss behavior corresponding to the pyrolysis of pendent groupsand nlain chains of the PI,respectively．
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发布时间：2021-03-19 - 摘要：A method determining molecular weight distribution index D (MWD) from viscosity versus shear stress flow curves for polypropylene has been presented．Based on the experimental data,the correlation between the viscosity η of molten polypropylene and its MWD can be expressed as η/ηo={1+α(τD)m}-1,where ηo is the zero shear viscosity,τ is the shear stress,α and m are empirical parameters Furthermore,a simpler method to estimate the MWD from only two experimental data,i．e．the melt index (MI) and the zero shear viscosity has also been presented,the calculated results are in good agreement with the data from GPC measurements．
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发布时间：2021-03-19 - 摘要：Silk fibroin(SF)/fucoidan blend films with different blend ratios were prepared by mixing aqueous solutions of SF and fucoidan The structural characteristics and thermal properties were examined through Fourier transform infrared (FTIR) spectroscopy,X-ray diffractometry (XRD),thermogravimetry,and differential scanning calorimetry (DSC) The conformation of SF in blend films was revealed to be a β-sheet structure,according to the results of FTIR and XRD spectra This result was also confirmed through DSC thermograms,the exotherm at around 230℃．that was attributed to the random coil conformation of SF．was not observed in blend films．These results demonstrated that the conformation change of SF occurred from a random coll to a β-sheet structure due to the formation of intermolecular hydrogen bonds between fucoidan and SF in the blend films．The crystalline SF films showed higher thermal stability than the amorphous SF film．
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发布时间：2021-03-19 - 摘要：N-[4-(aminosulfonyl)phenyl]acrylamide (ASPAA) was synthesized through the reaction of acryloyl chloride with sulfanilamide,and copolymefized with acrylonitrile (AN) and metbyl methacrylate (MMA),respeetivety．in DMF solvent using benzoyl peroxide as initiator at(70±0.5)℃．The copolymer composition was determined by using elemental analysis and the reactivity ratios of ASPAA/AN and ASPAA/MMA copolymerization systems were calculated by employing the Fineman-Ross and the Kelen-Tudos methods．The values of r1 and r2 obtained by the two methods fitted well with each other,i．e．r1(ASPAA)=1.43,r2(AN)=0.44 by Fineman-Ross method and r1(ASPAA)=1.39,r2(AN)=0.43 by Kelen-Tudos method for ASPAA/AN copolymerization system,and,r1(ASPAA)=0.88,r2(MMA)=1.42 by Fineman-Ross method and r1(ASPAA)=0.83,r2(AN)=1.35 by Kelen-Tudos method for ASPAA/MMA copolymefization system．
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发布时间：2021-03-19 - 摘要：Alginate microspheres were formed by coagulation of sedium alginate in CaCl2 solutions,followed by lyophilization which could create the porous structure．Bovine serum albumin (BSA) was incorporated into the nficmspheres by mixing BSA with sodium alginate prior to coagulation．The release behavior of BSA from the Ca-alginate microspheres was studied．Fuaher．the alginate microspheres loaded with BSA were embedded in PLGA films by mixing the alginme miemspheres with PLGA solutions in order to study the sustained release of BSA from the PLGA film,which is widdy used as cell scaffold materials in tissue engineering．The mlease behavior of BSA from the PLGA film embedded alginate mlcrospheres indicated potential application for keeping the bioaetivity of the growth factor．
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发布时间：2021-03-19 - 摘要：Magnetic ultrathin films were fabricated layer-by-layer using a serf-assembly method through the electrostatic interaction between the photosensitive diazoresin (DR) and the negatively charged Fe3O4 nanopartides (NP-Fe3O4)．The results of the UV-vis spectra and AFM show that the assembly of DR and NP-Fe3O4 is very Successful．After UV irradiation,the ionic bonds of the DR/NP-Fe3O4 film convert to covalent ones and the magnetic films become very stabletoward polar solvents．The magnetic film images with good resolution are obtained bymeans of selective UV-exposure of the film under a photo-mask and then developing the exposed film in the saturated aqueous solutian of sodium dedecyl sulfate (SDS) and cetyl trimethyl ammonium bromide (CTAB),respectively．
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发布时间：2021-03-19 - 摘要：It was demonstrated that the fast RAFT polymerization of styrene wlth almost pedect polymerization performance could be achieved by using a carefully designed miniemulsion polymerization system．With much higher levels of surfaetant (9 wt％ based on monomer) and co-stabilizer (5 wt％ based on monomer) than those in typical miniemulsion polymerization．the miniemulsion polymerization using 1-phenylethyl phenyl-dithioacetate as a RAFT agent showed a very fast polymerization rate,excellem performance of living radical polymerization during the entire polymerization process,and narrow particle size distributions．It was concluded that RAFT miniemulsion polymerization presented an excellent commercial process for a living radical polymerization system．
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发布时间：2021-03-19
Research Bulletin
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