最新刊期
卷 ， 期 5 ， 2002
- 摘要：Active center transformation polymerization from a radical to a cationic mechanism of para-methoxystyrene(MOS) was performed by using 2,2′-azoisobutyronitrile (AIBN) as a radical initiator and diphenyliodonium hexafluorophosphate(Ph2I+PK-6) as an electron acceptor．Block copolymers of poly(MOS-b-CHO／DECO) were prepared by one step by adding monomer cyclohexene oxide(CHO) and bifunctional monomer 1,2,5,6-diepoxycyclooctane (DECO) to the above system．Using bifunctional monomer DECO successfully eliminated homopolymers formed by chain transfer reaction during cationic polymerization．The polymers obtained by the system containing MOS,CHO,AIBN,Ph2I+ PF-6 and DECO were characterized by 1H-NMR,extraction separation,and gel permeation chromatography (GPC),etc．Neither homopolymer of PCHO nor copolymers of CHO and DECO (poly(CHO-co-DECO))were obtained by this system,suggesting the success and the efficiency of the method．
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发布时间：2021-03-19
Rapid Communications
- 摘要：Fluoropolymer films have so low surface energy that they have good special surface properties,such as water-resistant,oil-resistant and self-cleaning properties. Nowdays,surface properties of polyacrylates can be modified by introducing fluorine-containing groups to polymer chains．The acrylate copolymer emulsion containing fluorine was prepared,with fluoromoner (Zonyl TM),butyl acrylate (BA),methyl methylacrylate (MMA) as monomers,sodium dodocyl sulfonate (SDS) as emulsifier. The solid content of copolymer emulsion was about 25wt％．The kinetics of emulsion copolymerization was studied by the weight method. The effects of the concentration of emulsifier,initiator,monomer and polymerization temperature on polymerization rate (Rp) were investigated in detail. The results showed that Rp ∝ [SDS]0.28,Rp ∝ [I]0.98．The apparent activation energy was 50.756 kJ·mol-1．The copolymer emulsions had no change after stored at room temperature for 72 h,at 60℃ for 48 h and at-5℃ for 24 h respectively．The centrifugal stability of emulsions was characterized at 12000 r／min for 120 min The sedimentation ratios showed that the centrifugal stability of emulsions increased with increasing the amount of emulsifier,while decreased with increasing the amounts of initiator and fluoromonomer respectively. The latex films could be dissolved in THF and toluene,while could be swelled in methanol and ethanol．The water absorption of latex films decreased with increasing the amount of fluoromonomer. The surface property of films was determined by Wilhelmy method．The contact angles for latex films to water increased apparently by introducing fluorine-containing groups,above 100。．This result showed the water-resistant property of copolymer latex films containing fluorine was improved．
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发布时间：2021-03-19 - 摘要：Hydrophilic microporous membranes were prepared via the TIPS process using three hydrophilic ethylene-acrylic acid co-polymers with different co-unit contents and diphenyl ether．These co-polymer were confirmed to the hydrophilic by contact angle measurements．Cloud points were determined visuall by noting the appearance of turbidity under the microscope．The relevant crystallization temperatures for the thermodynamic phase diagram were determined by differential scanning calorimetry (DSC)．The crystallization temperature curves shifted to lower temperatures as the amorphous acrylic acid content of the co-polymer increased．The membrane structures were investigated by scanning electron microscope and related to the initial polymer concentration and acrylic acid content．As the polymer concentration increased or the acrylic acid content decreased,the pore size decreased． However,at the concentration above 50 wt％,the films had no microporosity．
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发布时间：2021-03-19 - 摘要：Polymer flooding agents play an important role in enhanced oil recovery (EOR)．A New way to prepare polymer flooding agents through complexation of two oppositely charged polymers has attracted much attention．Poly(acrylamide-co-dimethyldiallylammonium chloride)[P(AM-DMDAAC)] is a novel cationic polyeletrolyle which can be used as the component of polyelectrolyte complex for EOR．The basic parameters and behavior of P(AM-DMDAAC),in which cationic component is controlled,in 0.1 mol／L NaCl aqueous solution were characterized by dynamic and static laser light-scattering．The apparent basic parameters of P(AM-DMDAAC) are as follows：=5.04×l05 g·mol-1,〈Rg〉app=39.9 nm,A2,app=1.57×10-4 cm3 mol·g-2．From the results of dynamic light scattering,the curves of Dt versus c and scattering angle θ,all are nonlinear and turning down．The phenomena imply that both the chains of P(AM-DMDAAC) in 0.1 mol／L NaCl aqueous solution appear polydispersity and there are some associates．Furthermore,the distribution ranges of the hydrodynamic radii (Rh) can be divided into two parts,for Rh value,one part is relative smaller,another is relative larger．Reasonably,the later can be attributed to association. When temperature raises,both parts develop towards the direction of the reducing Rh,so the behaviors of association and disassociation are evidenced again．Under certain conditions,the existing of“metastable behavior” is a power circumstantial evidence for association behavior of P(AM-DMDAAC) in 0.1 mol／L NaCl aqueous solution．These results provide basic data for preparing novel flooding agents by complexation of polyelectrolyle.
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发布时间：2021-03-19 - 摘要：The non-isothermal crystallization kinetics of polypropylene grafted polyurethane (PP-g-PU) copolymers under the different cooling rate has been studied by DSC．A kinetic equation for nonisothermal crystallization was employed to analyze the crystallization characteristics of PP and PP-g-PU. The results show that in the range of cooling rate of 2.5 to 40 K／min,the kinetics of non-isothermal crystallization of PP and PP-g-PU with different PU content can fit the Avrami equation and a combination of Avrami-Ozwa method. The presence of the PU branches in PP-g-PU results in less crystallization enthalpy and higher crystallization temperature upon cooling．All the PP-g-PU copolymers have higher nucleation rate and overall rate of crystallization assuming that the spherulitic growth was initiated by heterogeneous nucleation alone,as characterized by the higher values of Zc and low values of t1/2 than those of pure PP．The crystallization rate is not only dependent upon the cooling rate,but also dependent on the composition ratio of PP-g-PU copolymers. It was found that,due to stronger hydrogen bonding effect among the PU branch chains,the mode of nucleation and the growth of the crystallites changed after grafting. The hydrogen bonding effect can accelerate the heterogeneous nucleation by strengthening the adsorption effect between PP chains,and result in different crystalline behavior from other PP copolymers,as proved by the fact that the n values of PP-g-PU copolymers increased with increasing cooling rate．
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发布时间：2021-03-19 - 摘要：A series of extended-chain ureas(Ui) containing polypropylene glycol(PPG) spacers with different molecular weight were synthesized．The reactive activity,dynamic mechanical behavior,impact property and morphology of the Ui modified E-51／dicy curing system were investigated systematically,the relationships among the dynamic mechanical behavior,impact strength and morphology were also discussed．Results show that the curing activity of modified E-51／dicy curing system was so greatly enhanced that the curing reaction peak temperature decreased from l90 to 140℃,and the apparent activation energy of curing reaction is reduced froml 145.5 kJ／mol to 70～80 kJ／mol．The impact strength of the Ui modified curing system was increased ignificantly,E-51／dicy/U1 (extended-chain area containing PPG flexible spacer with molecular weight 1000) system was 8 times higher than that of the unmodified E-51／dicy curing system,the fracture surfaces of the E-51／dicy/U1 systems displayed tough fracture feature,which is very different from that of the unmodified system．There exist two-phase microstructure for the modified curing systenm．This leads to the significant increasing in impact strength．
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发布时间：2021-03-19 - 摘要：A novel macromonomer,polystyrene capped with thienyl group (PST-Thp),which can undergos oxidation coupling polymerization,has been synthesized by anionic polymerization of styrene with butyl lithium as the initiator and 3-bromo-thiophene as the terminator．Its homopolymerization and copolymerization with thiophene in the presence of anhydrous ferric chloride produced poly(thiophene-g-styrene) (PThp-p-ST) and were studied by GPC,FTIR and UV-Vis spectroscopy. The homopolymerization just gave out polymacromonomer with very low polymerization degree．Copolymerization of PST-Thp with thiophene produced graft copolymer with conjugated main chain of polythiophene and narrowly-distributed branch chain of PST．Copolymerization conversion of PST-Thp and the fraction of the soluble of PThp-g-ST increase with molecular weight of PST-Thp．
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发布时间：2021-03-19 - 摘要：Many scholars have made contributions on the formulae of the colloidal dispersion gel (CDG) and the factors affecting on the gelation performance．However,few reports were concentrated on studying the microstructure of the CDG．Polyacrylamide(HPAM)／ Chromium acetate and HPAM／phenolic aldehyde colloidal dispersion gel,which come respectively from different cross-linking systems,inorganic and organic,were studied by the microscopic image analysis with the atomic force microscope(AFM)．All of the CDG is founded to present eventually a self-assembly branch-like fractal structure under the scanning range of micrometer magnitude,and the fractal of a single twig was formed by compact stock of nanometer particles on a smaller scale regardless of the concentration variation of HPAM and the cross-linking reagent in either inorganic cross-linking system or organic cross-linking system．It is revealed that formation and morphology of the branch-like fractal structure depend on the concentration of HPAM,and the presence and concentration of cross-linking reagent only affect the topography of branch-like gel fractal．Moreover,the experimental results demonstrate that the elastic modulus of the gel with the fractal structure formed by the nanometer colloid particles is higher one order of magnitude than that by micrometer ones,and that the smaller the particle diameter is,the higher the gel kinetic stability is．
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发布时间：2021-03-19 - 摘要：The interpolymer specific interactions between acrylate copolymers with proton donor and proton acceptor in solutions were investigated by means of viscometry and light scattering．Poly(styrene/acrylate/acrylic acid) as proton donating polymer(PDP) and poly(styrene／acrylate／4-vinylpyridine) as proton accepting polymer(PAP) with various macromolecular chain compositions were prepared by emulsion copolymerization and the complexed solutions formed by PDP and PAP were prepared. A novel interpolymer interaction parameter ka based on the relationship of viscositv enhancement factor with theoretical specific viscosity of the blend,ηsp,m,cal,has been developed to study the interpolymer specific interactions in toluene．The effects of the content and alkyl length of acrylate on interpolymer interaction were discussed．The results show that with the change in mole fraction of AA (FAA) in blends,there existed a maximal ka indicating the strongest interaction between PDP and PAP．The mole fraction of AA corresponding to maximal ka,FAA,max,increases gradually up to 0.5 as OA content decreases in PDP and relatively insensitive to composition of PAP. The interpolymer interaction between PDP and PAP is increased with increasing OA content in component copolymers due to Van der Waals force between side chains of OA unit on unlike macromolecular chalns．The enhancement of the interpolymer specific interaction can also be realized by increasing the alkyl length of acrylate．Light scattering experiments confirm that ka can act qualitatively as measure of the magnitude of the interpolymer interaction ability.
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发布时间：2021-03-19 - 摘要：The phase state of the catalytic system of Co(naph)2-Al(i-Bu)2Cl was investigated by the Tyndall effect,electronic microscope and super-filtering experiment．The results showed that the colloidal particle size of the Co(naph)2-Al(i-Bu)2Cl catalyst was dispersed in butadiene-contained toluene solvent within the range of nano-scale size．Under the optimum conditions,the diameter of the catalytic particles was from 1 nm to 100 nm and the catalyst belonged to multiphase catalyst．The active sites were located on the surface of the colloidal particles,while the catalyst particles were amorphous．The ratios of catalyst components affected the shape of colloidal particles,among which the colloidal particles of the optimum ratios were small in size,uniformly distributed and with high catalytic activity．This paper summarizes that the characteristic of colloid catalysts is similar to that of homogeneous catalytic system,but the catalytic activity was apparently affected by preparing methods such as component ratios,adding order and aging．It point out that kinetic conditions of colloid catalyst approximates to those of homogeneous system,i．e．in the initial stage of polymerization reaction．the monomer concentration is 102～3 times as great as that of alkylaluminium and the other components．
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发布时间：2021-03-19 - 摘要：A method for chemically attaching ultra-thin polymer films through the self-assembly of end silane terminated polymer is provided in this article．End trimethoxysilane functionalized polystyrene (PSt) was first prepared through radical chain transfer reaction and characterized by FTIR,1H-NMR and gel permeation chromatography (GPC)．The coincidence of the calculated molecular weight of the prepared end silane terminated PSt from both GPC and NMR proved high end functionalized ratio．The self-assembly behavior on silicon wafers of the obtained polymer was studied by measuring the contact angle,film thickness．The chemical characteristics and the nano scale morphology of the film were investigated with FTIR,X-ray photoelectro spectroscopy (XPS),atomic force microscopy (AFM)．It was found that homogeneous and complete polymer film could be formed only when the polymer concentration exceeded 1 mg／mL．The root mean roughness of the complete polymer was below 1 nm．The tribological properties of the prepared PSt film were investigated using a static-dynamic friction precision measurement apparatus．The friction coefficient of self-assembled PSt film against steel ball at a load of 0.5 N was in the range of 0.08～0.1 which was much lower than that for bare silicon wafers in the same experiment conditions (0.7～0.8)．Self assembled PSt modified silicon wafers exhibited excellent friction reduction and anti-wear behavior comparing with their bare counterparts．According to this investigation,serf-assembled polymer films have the prospect for friction reduction and wear resistance．
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发布时间：2021-03-19 - 摘要：It is firstly reported that after the rapid formation of a gel by mixing of the MMA and neodymium triisopropoxide．the PMMA hybrid materials containing neodymium Nd(x)／PMMA were prepared by the in-situDolymerization．It has been characterized by FT-IR,TG,XWAD,DMTA,SEM etc,which indicated that there is coordination interaction between neodymium (Ⅲ) ion and carboxide (C=O) in the PMMA and the resulting crosslink network structure in the PMMA hybrid materials．The Nd／PMMA materials couldn’t dissolve but only could swell in most good solvents of PMMA．The introduction of triisopropoxyl neodymium could improve the heat resistance and toughness of PMMA．Dynamical mechanical thermal analysis shown that storage modulus (E′) of Nd／PMMA materials increased and glass transition temperature (Tg) decreased with increasing Nd content．Moreover,the preparation method of the non-water gel in-situ polymerization overcome the association of rare earth ions in the materials,and results in formation of the triisopropoxyl neodymium／PMMA hybrid materials with high rare earth content and uniform distribution．
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发布时间：2021-03-19 - 摘要：A novelβ-cyclodextrin (β-CD) based monomer (MAH-β-CD) containing vinyl and earboxyl functional groups was synthesized by reaction ofβ-CD with maleic anhydride (MAH) in N,N-dimethylformamide (DMF) at 80℃．Through copolymerization of this functional monomer with N-isopropylacrylamide (NIPA) in aqueous solution,a novel hydrogel (poly(NIPA-co-MAH-β-CD) with pH-,temperature- and ionic strength sensitivities as well as with molecular inclusion behavior,was obtained using radical polymerization method．Both MAH-β-CD monomer and the gels obtained were characterizited using 13C-NMR,IR spectra,and element analysis．The equilibrium swelling ratios (ESR) of the hydrogels have been investigated under conditions of different pH,temperature and ionic strength．The results indicated that the ESR presents remarkable response to changes of pH,temperature,or ionic strength．Interestingly,under higher content of —COOH groups and weak base,the hydrogel still possesses evidently temperature-sensitivity behavior．
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发布时间：2021-03-19 - 摘要：A new method was applied to study kinetics of hydrolysis reactions of silazane compounds,which were used as additives in silicone rubbers to improve their thermal stability．It was shown that the hydrolysis reaction was a first-order reaction versus the concentration of the silazane compound．Activation energy(Ea) was calculated for reactions of several silazane compounds with water vapor．It was indicated that activation energy of hydrolysis was closely related with the structure of the silazane compound. The hydrolysis stability would increase when groups around silicon atom or nitrogen atom were of high steric hindrance．Hydrolysis activation energy of hexaphenylcyclotrisilazane 4 was 214 kJ／mol,and that of polymer 5 which contained cyclodisilazane in backbone was 291.3 kJ／mol．Thermal stability of silicone rubber could be improved more effectively when silazanes with higher Ea were used as additives．The weight loss of silicone rubber with compound 4 and 5 as additive was 0.96％ and 0.6％,respectively,when aged under 350℃ for 24 h．
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发布时间：2021-03-19 - 摘要：PEG macromonomer with one methacryloyl end group for per polymer chain was selected as reaction stabilizer. PEG grafted poly (acrylonitrile/styrene) particles with sub-micron to nano sizes were prepared by dispersion copolymerization of acrylonitrile with styrene using 2,2′-azobisisobutyrnitrile (AIBN) as a free radical initiator in the presence of PEG macromonomer in ethanol／water (Vol／Vol=7／3) mixed solvents at 60℃ for 24 h．The nanoparticles having narrow size-distribution were observed based on the studies of transmission electron microscopy (TEM) and laser light scattering (LLS). The surfaces of the nanoparticles have unusual structures which can be control by changing molecular weight of PEG macromonomer and other reaction conditions．The dynamic diameter of the nanoparticles can be controlled in range from 110 to 920 nm by changing reaction factors such as solvent composition,concentration of PEG macromonomer or styrene．X-ray photoelectron spectroscopy analysis shows PEG segments were covered into the surfaces of the nanoparticles．The structure of the freeze-dried nanoparticles was investigated by XRD．XRD pattern of any particles showed a distinct diffraction peak at 2θ=22.6。corresponding to a spacing of 0.39 nm and some small peaks in the 2θ range of 5～30。,indicating that the particles are crystallized．
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发布时间：2021-03-19 - 摘要：Surface grafting polymerization of cast polypropylene (CPP)／acrylic acid(AA) system was studied with two-step method,which is a novel technique advantageous over traditional surface grafting polymerization initiated by UV．It consists of two steps. Firstly,dormant groups (semi-benzopinacol) were introduced on the CPP film under UV irradiation in the presence of benzophenone (BP) solution；and then,AA was grafted on the substrate surface by thermoactivating polymerization．The principle is as following,after BP is excited with UV irradiation,it extracts the H atoms from CPP surface and is reduced into semipinacol free radicals,meanwhile macromolecular free radicals are produced on CPP film surface．Because of spatial hindrance originated from its aromatic group,it is difficult for semipinacol free radicals to perform coupling termination and so does the surface radical．If no monomer was available,these two kinds radicals will combine．When CPP film with dormant groups is heated in a monomer solution,the C—C bonds of surface semipinacol groups break into the surface free radicals and semipinacol free radicals．The surface radicals induced monomer to propagate,result in grafting chains；whileas the reactivity of semipinacole free radical is too low to initiate grafting polymerization．Consequently,this method has two advantages：high grafting efficiency and suited to more monomers which can not be used directly in traditional photografting polymerization．The results show that acetic anhydride is an ideal solvent for CPP／AA surface grafting system；grafting yield increases with the growth of photosensitizer and monomer concentration；and polymerization temperature has positive effect on grafting yield．The contact angle of grafted CPP film against water decreases with the increase of grafting yield．In addition,the grafted CPP-g-AA film was identified by FTIR spectra．
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发布时间：2021-03-19 - 摘要：The results of preliminary studies of a new polymer electrolytes based on poly(lithium acrylate),PAALi,with low-melting-point eutectic lithium salts consisted of lithium nitrate and lithium acetate were described．The inverse emulsion polymerization of PAALi was prepared from crylic acid and LiOH under optimum conditions of pH 13,oil／water ratio of l:1,polymerization time 4 h．The ion conductivity of PAALi was measured at range of l0-9～10-10S·cm-1．Thin films of these electrolytes were obtained by coating homogeneous molten mixtures of known masses of host polymer and salt．Electrolytes with compositions of n between 5 and 95,where n represents the mass ratio of the low-melting-point eutectic lithium salt,have been prepared．These solid polymer electrolytes were characterized by measurements of total ionic conductivity,IR,XRD,differential thermal analysis (DTA) and thermogravimetry(TG)．The highest conductivity (approximately 2×10-5S·cm-1) was found at room temperature (30℃) with the electrolyte composition of n equal to 80．XRD,DTA and TG-DTG results indicated that a new complex was formed．DTA result show that the melting point of SPE is at 196℃ (peak temperatuIre),and the temperature of decompostion is at 273℃．TG-DTG reveal that the temperature of SPE is 92℃ lower than that of PAALi,which may be as consequence of interaction between lithium salts and PAALi,weakening the bonds within the macromolecular backbone and making it less resistant to thermal degradation．
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发布时间：2021-03-19 - 摘要：High molecular weight polyetherketones based on 4-(4-hydroxyphenyl)-l-phthalazinone(DHPZ) ／4,4′-thiobisphenol TBP／4,4′-diflourodiphenylketone (DFK) were prepared by aromatic nucleophilic substitution reaction involving the toluene,N-methyl-2-pyrrolidone(NMP) and anhydrous potassium carbonate．The copolymer having 50％ TBP molar content was characterized by FT-IR and 1H-NMR．The results indicated that the copolyetherketones contained sulfide and phthalazinone moieties．13C-NMR spectra were used to indentify the structure of copolyetherketones．According to 13C-NMR spectra,it was found that the structural repeat units were randomly distributed in the molecular chain of the copolyetherketones. The Glass transition temperatures (Tg) were determined by differential scanning calorimetry (DSC) after being kept 5 min to remove the thermal history and cooling to room temperature at approximately 100 K／min．the results showed that no melting point temperature was detected and all the polyetherketones have only one Tg in the range of 137℃ to 263℃ and the Tgs decrease linearly with the increase of sulfide moiety in the copolymers,which further indicated all of the polyetherketones are random or homogeneous．The wide angle X-ray scattering was used to detected the crystallization of copolyetherketones．No crystal was formed for all the samples containing less than 70％ TBP structure in the copolyetherketones and the polyetherketone polymerized by DFK and TBP was semicrystallization having melting point temperature of about 262℃. The results of the copolymers stress-strain behavior indicated that,with the increase of sulfide moiety in the copolymers from 10％ to 30％,the strain at break increased obviously．The solubility tests showed that the copolymers having more phthalazinone moiety have better solubility in some polar solvents．
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发布时间：2021-03-19 - 摘要：Chloropropylene epoxide homopolymer (CER) crosslinked by DCPD (COOK)2 as crosslinker with 88.75％ gel content was obtained by solution reaction,the effect of the kinds of solvent,the dosage of crosslinker and calalyst(TBAB),reaction temperature and time on the amount of polymer gel formation were studied．The results indicated that the crosslinking reaction accelerates with the acsension of the reaction temperature and time,increase of dosage of crosslinker and catalyst．Solvent affected the crosslinking reaction and the result indicated that the reaction was most efficient in DMF．It was proved by IR that the gel was generated through esterification between the chlorine on carbon of CER and the carboxylic salt group of the crosslinker by eliminate KCl．The test of reaction solubility of crosslinked CER react with maleic anhydride (MA) indicated that the crosslinked CER exhibits a thermally reversible behavior due to the dimmer(decyclopentadiene)／monomer(cyclopentadiene) conversion of -DCPD-moieties in the crosslinkage of the copolymer,the percentage of thermally reversible conversion were decrease with the ascension of the reaction temperature,the amount of crosslinker increasing．Based on the crosslinking reaction,a novel thermoplastic elastomer of CER with higher heat-resistance and oil-resistance was obtained.
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发布时间：2021-03-19 - 摘要：Synthesis and characteristics of poly(fluoropentyl methacrylate-co-vinylimidazole) (FIm),and oxygen-binding properties of its complex with meso-α,α,α,α-tetrakis(o-pivalamidophenyl)porphyrinato cobalt(Ⅱ) (CoP) were studied．FIm was prepared by radical copolymerization of octafluoropentyl methacrylate with 1-vinylimdazole using azobis(isobutyronitrile) as the initiator．The vinylimidazole content and molecular weight of the FIm copolymer were determined to be 25 mol％ and 5.0×104 by elemental analysis and GPC,respectively．FIm and CoP in solution were mixed to complex the imidazulyl residue of the copolymer with the fifth coordination site of CoP under nitrogen atmosphere to yield both art active and homogenous dispersed CoP for oxygen-binding．Oxygen-binding to the CoP-FIm complex was measured spectroscopically with a UV spectrophotometer．The CoP-FIm complex displayed areversible change in the visible absorption spectrum from the deoxy form to the oxy or oxygen-binding one with an isosbestic point,in response to the partial oxygen pressure of the atmosphere．The oxygen-binding equilibrium curves obeyed a Langmuir isotherm,to give the oxygen-binding affinity P50 (oxygen partial pressure at which half of the CoP binds with oxygen)．Solvent has great effect on the oxygen-binding properties of the complex．The oxygen-binding affinity of the CoP-FIm complex in tetrabydrofuran was larger than that in N,N-dimethyl formamide solution．It is assumed that a N,N-dimethyl formamide molecule weakly coordinated to the sixth site (oxygen-binding site) of CoP to reduce the oxygen-binding affinity．On the other hand,the oxygen-binding site of the CoP complex could be maintained vacant in tetrabydrofuran before the oxygen-binding．The binding and dissociation rate constants of oxygen to and from the CoP (kon and koff,respectively) for the CoP-Flm solution were large,which indicates a very rapid and reversible oxygen-binding by CoP．
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发布时间：2021-03-19 - 摘要：The membrane formation mechanism of PVDF／DMAc／H2O／Additive svstem was studied．The additive was PVP,PEG or LiCl respectively. The phase diagram for polymer solution of PVDF／DMAc／Water/Additive system was measured using cloud-point method. The phase separation phenomena during membrane formation process were recorded using light transmission experiment．The crystallinity of membrane was detected by DSC．The result shown both gelation and liquid-liquid demixing existed during phase-inversion process of casting solution with different additive．Gelation appeared early at lower nonsolvent concentration than liquid-liquid demixing in the range of 30～60℃. LiCl as additive lead to a strong action for PVDF solution to form gel than PEG or PVP．This incteased the mass transfer resistance in nascent membrane and the liquid-liquid demixing delayed time prolonged along with the sequence of PVP,PEG or LiCl as additive during membrane formation process．The polymer concentration of nascent membrane at the onset of liquid-liquid demixing increased and restricted the development of macrovoids．The strong gelation tendency of polymer solution intensified the solidification of nascent membrane and restricted the macrovoids development further．Thus the macrovoids structure extended to the bottom and stopped with the sponge-Iike structure when PVP was used as additive．When the additive was PEG or LiCl．the macrovoids developed insufficiently and terminated in the middle of membrane with the sponge-like structure and then passed to nodular structure in bottom．The effective porosity and flux decreased and crystallinity increased along with the sequence of PVP,PEG or LiCl as additive．The hydrophobicity of membrane with LiCl as additive was barely changed,but the water-resisting pressure of membrane with PVP or PEG as additive decreased about 20 kPa．
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发布时间：2021-03-19 - 摘要：N-Ethyl chitosan (NECS) with degree of substitution 0.94 was prepared from chitosan and acetaldehyde．The films of NECS were prepared via the solution casting technique using formic acid as solvent．The crystalline structure and crystallization process were investigated by means of polarized optical microscopy,scanning electron microscopy and X-ray diffraction．Thousands of needle-like crystals,which are seldom found in polymers,were observed in NECS cast films after few days casting. The needle-like crystals were formed from spherulites through a psot-crystallization process．The shape of needle-like crystals was long rectangle with a typical size of ～50 μm(length)×2～5 μm(width)×1～2 μm(height),and molecular chains are parallel to the long axis of the needles．The neddle-like crystals were first found on the centers of the spherulites．and then on every ioint of dendritical fibrils of spherulites,at last on everywhere of spherulites．Generally speaking,the needle-like crystals basically oriented at the direction of radius of spherulites(also the direction of molecular chains) and decorated the sphrulites．The possibility of post-crystallization was explained by the results that the cast films became super-concentrated solutions(＞80％)after the adsorption of moisture because of the hydrophilic properties of NECS. The remained solvent and absorbed water were used as plasticizers,which increase the mobility of polymer chains. The dendritic crystals consisted of needle-like crystals were also found in the systems．
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发布时间：2021-03-19 - 摘要：Syndiotactic polystyrene (sPS) is a new class of thermoplastics and is unusual among polystyrenes for its properties．Since Ishihara reported on the titanium complexes with mono-cyclopentadienyl ligand for production of sPS,a lot of catalysis for styrene syndiotactic polymerization has been reported in the literature．A series of half-metallocene complexes have been reported in our studies,these catalysts have high stability and activity for olefin polymerization with low molar ratio of aluminium／titanium and produce polymers with different chain microstructures．In the paper,synthesis of half-metallocene complexes [CpTi(dbm)Cl2] and [CpTi(dbm)2Cl] containing β/i>-diketone ligand are discribed．It is proved by the experiments that [CpTi(dbm)Cl2] is active for styrene polymerization at 40℃ with MAO activation,and exhibits higher activity than CpTiCl3．Giving the polymers with high syndiotacticity.For the [CpTi(dbm)Cl2]／MAO system,the activity is “up and down” type with increase in the Al／Ti molar ratio,and up to the highest when the Al／Ti molar ratio is about 500,10.7×l05 gPS／molTi·h or so；also the active decreases when the polymerization time is too high．The polymers prepared by [CpTi(dbm)Cl2] were extracted with boiling n-butanone and characterized by 13C-NMR．
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发布时间：2021-03-19 - 摘要：Poly (ethylene terephthalate-co-p-oxybenzoate) (PET／HBA) is the first reported liquid crystalline polyester,and has higher strength than that of poly(ethylene terephthalate) (PET). However,there ale two problems for the PET／HBA copolyester,chemical structure control and normal mechanical properties．Stepwise feed mode of p-oxybenzoate (HBA) can solve the first problem．The other should be solved by adding some flexible or non-linear monomers,but it will decrease the oriented mechanical properties．According to the fractile theoretic calculation,a fractile monomer,trihydroxy benzene (TOP),was introduced into the chain of PET／HBA copolyester to reduce the melting point and improve the processing properties of PET／HBA copolyester,and finally to increase the oriented and normal mechanical properties．The effects of copolycondensation time,acetylization time,pressure,TOP and HBA concentrations on the inherent viscosity of novel fractile copolyester were investigated．The effects of TOP and HBA concentrations on the melting point and isotropic temperature of novel fractile copolyester were also studied．A novel copolyester with fractile structure was obtained．With the increasing of TOP concentration,there were a maximum of the inherent viscosity and a minimum of the melting point for the novel copolyester．The melting point was lowered 10℃ or more than that of PET／HBA copolyester. But the isotropic temperature and liquid crystalline texture of the copolyester was not changed with the increasing of TOP concentration．So,the range of liquid crystalline was enlarged．
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发布时间：2021-03-19 - 摘要：A kind of styrene-butadiene (S／B) multi-block copolymer was bulk-polymerized in a twin-screw extruder with the anion initiators and mixed S／B monomers．The effects of screw rotational speed,feed rate of monomers and St content on the conversion of styrene and S／B mixture were researched．S／B block copolymer was characterized by 1H-NMR,IR,DMA．It is shown that a lot of short polybutadiene blocks and a little random structure coexist in the copolymer．It also can be seen in TEM photographs that the polybutadiene blocks,while being less than 15％ in whole composition,can retract into the ball shape 30～50 nm in diameter．On lhe other hand,the toughness,especially the elongation at break,of the copolymer grows stronger with the increase of butadiene content．
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发布时间：2021-03-19
Research Article
- 摘要：An epoxy resin based on diglycidyl ether of bisphenol A(epoxy resin E-51)was toughened with a liquid-crystalline epoxy resin,4-expoxypropoxy phenyl-4′-epoxypropoxy benzoate (PHBHQ) which presented a Schlieren texture in the temperature range of 131 ～ 94℃ during cooling．A mixed aromatic diamine,4,4′-diaminodiphenylmethane(DDM)：4,4′-diaminodiphenylsulfone(DDS)：4,4′-diaminodiphenylester(DDE)=5:2:1 weight ratio,was used as the curing agent,and the curing conditions were adopted as 100℃／1 h,120℃／2 h,150℃／2 h and 180℃／2 h. The influence of PHBHQ on the properties of final resin systems was investigated．Compared with other toughing agents such as rubbers and thermoplastic resins,PHBHQ can improve the toughness of epoxy resin E-51 greatly without affecting the modulus and thermal resistance．The impact strength of epoxy resin E-51 modified with 50 wt％ PHBHQ reached 40.2 kJ／m2,which was higher than that of pure epoxy resin E-51 system with 23.4 kJ／m2．The thermal property of toughing epoxy resin systems was tested with dynamic mechanical thermal analysis (DMTA)．The results showed that the glass transition temperature increased about 30℃ with only 9 wt％ PHBHQ．Wide-angle X-ray Diffraction(WAXD)was used to characterize the crystalline structure．Two diffraction angles were observed at the 9。and 23。,which showed that the nematic molecular arrangement has been kept during the crosslinking of the toughing system when the reaction was carried out in the thermal stability range of liquid-crystalline phase. A two-phase structure was observed on the fracture surface by scanning electronic microscopy (SEM)．The oriented mesogenic domain which was dispersed in the continuous epoxy matrix can initiate,branch and terminate the cracks and endow toughening epoxy networks with excellent overall properties
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发布时间：2021-03-19 - 摘要：Hyperbranched polyacrylate copolymers were synthesized by self-condensing vinyl copolymerization (SCVCP) of 2-[(2-bromopropionyl)oxy] ethyl acrylate (BPEA) and methyl acrylate (MA) in the presence of atetrafunctional initiator(THABI)．The structures of the polymers obtained were characterized by 1H-NMR and SEC／refractive index (RI)／right anagle laser light scattering (RALLs)／differential viscometer (DV)．Molecular weight (MW),molecular weight distribution (MWD) and degree of branching (DB) were influenced by conversion and initial feed molar ratio of BPEA,MA and THABI．The addition of THABI can narrow the MWDs of the polymers obtained. The results ale consistent with our simulation result.
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发布时间：2021-03-19 - 摘要：Bismaleimides bearing electron-donating chromophore moieties,i．e．N,N-bis (4-maleimidophenyl)-methylamine (BMIPMA),and its saturated model compound N,N-bis (4-succinimidophenyl)-methylamine (BSIPMA) were synthesized and their absorption and fluorescence behaviors were investigated．It was found that BMIPMA possess a strong fluorescence structural self-quenching effect (SSQE)．There is almost no fluorescence emission observed for BMIPMA,whereas its saturated model compound BSIPMA displays a strong fluorescence emission at the same chromophore concentration．On the basis of the SSQE,a new fluorescence approach was developed to monitor the process of the copolymerization of bismaleimides with diamines,which can directly reflect the consumption of the C=C bond of maleimide unit．The results agreed well with that obtained by 1H-NMR measurement pused．
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发布时间：2021-03-19 - 摘要：Due to the poor salt tolerance and heat resistance of the partially hydrolyzed acryl amide in the reservoir of high temperature and high inorganic salt,and the poor ability of shear,the hydrophobically associating terpolymersacrylamide-hexadecyl ally ammonium chloride-2-acrylamino-2-metyl propane sulfuric acid (AM-C16 DMAAC-AMPS) is prepared by micelle polymerization with the nonionic monomer-AM,the anionic monomer-AMPS,the cationic monomer-C16 DMAAC,It is investigated that the effect of the content of the hydrophobic monomer,anionic monomer,cationic monomer,reaction temperature and the concentration of the inorganic salt and the surfactant on the viscosity of the hydrophobically associating aqueous soluble terpolymers in brine．The results show that the aqueous soluble hydrophobically associating terpolymers(1000 mg/L) have good viscofication effect in brine(20000 mg/L),when the content of the hydrophobic monomer is l.2％,and of the anionic monomer is 30％,the hydrophobically associating terpolymers can meet the need of polymer flooding in reservoir of the high concentration inorganic salt．
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发布时间：2021-03-19 - 摘要：A series of multiblock copolymers of PLLA-PEG(PLE) with high molecular weight were synthesized by coupling PLLA-PEG-PLLA triblock copolymers with succinic anhydride in the presence of (N,N-dimethylamino) pyridine(DMAP) and dicyclohexylcarbodimide (DCC)．The results of the viscometry measurement,GPC and 1H-NMR,elucidated that multiblock PLE copolymers with high content of short PEG segments(Mn=2000) had been successfully obtained．The crystallinity of the copolymers was investigated by X-ray diffraction．Mechanical testing showed that multiblock copolymers had relatively high tensile strength and large elongation．In a word,the measurements showed that the multiblock PLE copolymers had high content of short PEG egments(Mn=2000),high molecular weight(Mw-100,000),excellent hydrophilicity and mechanical properties．The results of cells cultured on the multiblock PIE copolymer indicated that it might be suitable to be utilized as cell scaffold for tissue engineering．
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发布时间：2021-03-19 - 摘要：This work provides a new method to prepare crosslinkable multi-hollow micro-spheres of epoxy resin dispersible in water by incomplete phase inversion emulsification in the presence of a catalytic curing agent．The key is to add the curing agent in the vicinity of the phase inversion point at low temperature so as to control the emulsifier capability of the pre-curing oligomers at a low level,which ensures the achievement of incomplete phase inversion emulsification．Scanning electron micrographs of the spheres reveal that the particles size is mainly in the range of l～10 μm with sub-micron cavities within the spheres．DSC is used to measure the curing behavior of the spheres．Two broad exothermic peaks around 120 and 162℃ are found in the as-prepared particles,while the first peak shifts to higher temperature 135℃ and the onset temperature exceeds 100℃ in the thermally treated sample at 95℃ for 1.5 h．This indicates that the initial step curing process under the post-treatment conditions is nearly completed．After further treated at high temperature for example 200℃,a glass transition temperature about 130℃ is found,and the two peaks disappear due to a full achievement of the curing process．Extraction results show that after treated at 95℃ for 1.5 h in water,the micro-sized spheres become insoluble. It is concluded that the entitled waterborne microspheres are crosslinkable and multiporous．A preliminary result demonstrates a potential application of the entitled multi-hollow spheres as opacifiers due to their intensive light scattering within the hollows．
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发布时间：2021-03-19 - 摘要：A new iron based catalyst 2,6-bis[(1-fluorenylimino)ethyl] pyridine iron dicloride (2) was synthesized via Shift base condensation with 2,6-diacetylpyridine and 9-aminofluorene hydrochloride under formic acid as catalyst．Ethylene oligomerizations were carried out using this new catalyst and methylaluminoxane as cocatalyst under various conditions．The effects of Al／Fe molar ratio,reaction temperature and ethylene pressure on catalytic activity and product distribution were investigated．This novel catalyst had a good activity for ethylene oligomerization (e．g．4.21×106g oligomers·mol-1 Fe·h-1,Al/Fe molar ratio=2000,reaction temperature=40℃,ethylene pressure=1.5 MPa). The catalytic activity increased with the increasing concentration of MAO．The tendency to produce more C4～C10 olefins was attributed to the more chain transfer reactions to MAO．The higher the reaction temperature,the lower catalytic activity was present. The reasonable explanation was the combination of the accelerated catalyst’S deactivation and the decrease in ethylene concentration in solvent due to the elevated temperature．Under such condition,however,the oligomerization of ethylene produced more short chain olefins which are adapted to act as comonomers for preparation of linear low density polyethylene materials．Ethylene pressure in autoclave also had an important influence on catalytic activity and carbon-number distribution of product. The catalytic activity increased sharply with the elevated ethylene pressure．However,the proportion of C4～C10 olefins in product decreased in higher pressure due to the enhanced chain propagation reaction. The research work indicated that the control of catalytic activity and product distribution can be realized by the variation of oligomerization conditions such as Al／Fe molar ratio,reaction temperature and ethylene pressure．The results also showed that the ethylene oligomerization employing this novel iron-based catalyst mainly produces the C4～C10 olefins with high selectivity for linear C4～C10 α-olefin (＞98％)．
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发布时间：2021-03-19
Research Bulletin
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