X-射线光电子能谱研究偏二氯乙烯-丙烯酸甲酯共聚物的光解反应

用X-射线光电子能谱(ESCA)方法研究了偏二氯乙烯-丙烯酸甲酯共聚物(VDC-Co-MA)在大气及惰性气氛下的紫外光解反应,从ESCA信息随光照时间的变化规律探讨了几种可能存在的光化过程;结果还表明其碳-氯键断裂速度比聚偏二氯乙烯(PVDC)快;此外,由于同一碳上氯取代度的不同,使PVDC和PVC在大气环境中的光化反应有明显差别。     

PHOTO-INDUCED DOPED POLYANILINE BY THE VINYLIDENE CHLORIDE AND METHYL ACRYLATE COPOLYMER AS PHOTO ACID GENERATOR

The emeraldine base form of polyaniline (PANI) can be doped by a photo-induceddoping method. In this method a copolymer of vinylidene chloride and methyl acrylate(VCMAC) was used as photo acid generator which can release proton when it is exposedto ultraviolet light (λ= 254 nm). The structure of PANI-VCMAC system before and afterirradiation was characterized by elemental analysis, IR, XPS, and SEM images. Resultsobtained indicate that the photo-induced doping characteristics, such as doping positionand type of charge carriers, are similar to that of PANI doped with HCl. The poor room-temperature conductivity (～10~(-5)S/cm) of PANI-VCMAC system after irradiation maybe due to low doping degree (～pH= 3) and the difference in morphology as compared withPANI-HCl film.     

BARRIER PROPERTIES OF VINYLIDENE CHLORIDE/METHYL ACRYLATE COPOLYMER

A series of vinylidene dichloride (VDC) copolymers with methyl acrylate (MA) ascomonomer (3--12wt%), was prepared by free-radical suspension copolymerization. Thepermeability coefficients of the copolymers to oxygen and carbon dioxide were measured at1.0 MPa and at 30℃, and those to water vapor were measured at 30℃ and 100% relativehumidity All the VDC/MA copolymers studied are semicrystalline. As the MA contentincreases, the permeability coefficients of the copolymers to oxygen, carbon dioxide, andwater vapor are progressively increased, caused by decrease in crystalline fraction andincrease in free volume of VDC/MA copolymers.     

THE STUDIES OF THE CURING OF AN EPOXY RESIN ON COPPER WIRE BY FTIR EXTERNAL REFLECTION SPECTROSCOPY

The epoxy coating on copper wire has been studied by a modified sampling technique using Fourier transform infrared (FTIR) diffuse reflectance attachment. As the wire axis was parallel to the incident plane, a reflection spectrum of thin layer coating on a copper wire can be obtained. The study found that imidszole, especially the acetic acid treated imidazole, can be used as an effective curing catalyst of the epoxy resin on copper. This is the first report about the IR study of coatings on metal wires.     

STUDY ON THE MISCIBILITY OF DYNAMICALLY VULCANIZED EPDM/PP BLEND BY POSITRON ANNIHILATION SPECTROSCOPY*

Positron annihilation spectroscopy (PAS) was utilized to investigate the relationship between the free-volume holeproperties and miscibility of dynamically vulcanized EPDM/PP blend. The results showed that the noncrystalline region ofPP and EPDM in the blend was partially miscible and the miscibility of the blend became worse when the weight percent ofEPDM was <50%. This was also demonstrated by DMTA and mechanical properties of the blends with variouscompositions.     

DETERMINATION OF DEGREE OF CRYSTALLINITY OF NYLON 1212 BY WIDE-ANGLE X-RAY DIFFRACTION

Based on the X-ray scattering intensity theory and using the approximate expression for the atomic scattering factor, the correction factors for three crystalline peaks and an amorphous peak of Nylon 1212 were calculated and the formula of degree of crystallinity of Nylon 1212 was derived by a graphic multipeak resolution method. The degree of crystallinity calculated from the WAXD method is compatible with those obtained by density and calorimetry methods.     

STUDIES ON THE HYDROGENATION OF METHYL ACRYLATE CATALYZED BY Pd/DVB CROSSLINKED POLY-(N-VINYL PYRROLIDONE)

Many kinds of dispersed Pd (0) supported on cross-linked poly (N-vinyl pyrrolidone) were prepared and characterized by IR and X-ray diffraction. Their hydrogenation properties of methyl acrylate have been examined. Experimental results indicate that the hydrogenation rate will reach a maximum as the degree of crosslinking increases to a certain point. The catalytic activity of the catalysts is closely related to the preparation condition and the particle size of Pd of the catalysts. Some other factors which affect the catalytic properties have also been studied.     

INVESTIGATION OF MICROSTRUCTURE AND CONDUCTIVE MECHANISM OF HIGH DENSITY POLYETHYLENE/CARBON BLACK PARTICLE COMPOSITE BY POSITRON ANNIHILATION LIFETIME SPECTROSCOPY

The microstructure and conductive mechanism of high density polyethylene/carbon black (HDPE/CB) compositewere investigated by positron annihilation lifetime spectroscopy (PALS). The PALS were measured in two series of samples,one with various CB contents in the composites and the other with various γ-irradiation doses in HDPE/CB compositecontaining 20 wt% CB. It was found that CB particles distribute in the amorphous regions, the CB critical content value inHDPE/CB composite is about 16.7 wtO/ and the suitable γ-irradiation dose for improving the conductive behavior ofHDPE/CB composite is about 20 Mrad. T'he result observed for the second set of samples suggests that γ-irradiation causesnot only cross-linking in amorphous regions but also destruction of the partial crystalline structure. Therefore, a suitableirradiation dose, about 20 Mrad, can induce sufficient cross-linking in the amorphous regions without enhancing thedecomposition of crystalline structure, so that the positive temperature coefficient (PTC) effect remains while the negativetemperature coefficient (NTC) effect is suppressed. A new interpretation of the conductive mechanism, which might providea more detailed explanation of the PTC effect and the NTC effect has been proposed.     

EFFECT OF TACTICITY OF PMMA ON CRYSTALLINE STRUCTURE OF POLY VINYLIDENE FLUORIDE

Fourier transform infrared spectroscopy (FTIR) has been used to study the effect of tacticityof PMMA on β phase formation of poly vinylidene fluoride (PVF_2) during quenching process.For pure PVF_2, quenching at lower temperature results in the formation of β phase crystallites.The critical quenching temperature for β phase formation is about 30℃. Adding a given amountof PMMA (30%) results in the increase of the critical quenching temperature. For the blends ofPVF_2 with atactic PMMA (a-PMMA), the critical quenching temperature is about 45℃, whilefor the blends with syndiotactic PMMA (s-PMMA), attains to about 70℃.     

SYNTHESIS OF POLY(ETHYLENE TEREPHTHALATE)-POLYCAPROLACTONE BLOCK COPOLYMER BY DIRECT COPOLYMERIZATION*

Poly(ethylene terephthalate) -polycaprolactone block copolymer (PCL- b-PET) is a polyester withimproved biodegradability. In the present paper, a new direct copolymerization method of ε-caprolactone (ε-CL) and bishydroxyethylene terephthalate (BHET) in the presence of Ti(OBu)_4 was proposed for thesynthesis of PCL-b-PET. The PCL-b-PET copolymer was characterized by IR, GPC and ~1H-NMRtechniques, and the effects of synthesis conditions, such as temperature, reaction time and concentration ofcatalyst on the copolymerization were discussed.     

THE STRUCTURE AND OPTICAL PROPERTIES OF COPOLYMER OF CHOLESTERIC ESTER

The structure and switching properties of liquid crystalline side chain copolymers of cholesteric ester of 1,2-hydroxypropyl 2,4-di-isocyanatoluene methylmethacrylate (PHCPM) have been studied in detail. The cholesteric mesophase of PHCPM is shown by polarizing microscopy, X-ray diffraction and selective light reflection. Solution of PHCPM in CHCl_3 is optically anisotropic; its optical properties were determined by specific rotation [α], circular dichroism (CD) and wide-angle hght scattering (WALS) methods.     

SYNTHESIS AND PROPERTIES OF TRANSPARENT THIODIGLYCOL DIMETHACRYLATE COPOLYMER RESINS

The title compound, thiodiglycol dimethacrylate (TDGDMA), was synthesized from thiodiglycol and methacryloyl chloride by phase transfer catalysis reaction, and its structure was confirmed by FTIR and 1H-NMR analyses. TDGDMA possesses good polymerizability to produce a homopolymer resin with excellent transparency (T%, 90), moderate refractivity (nd20, 1.55), lower dispersivity (Abbe‘s number, 50.6) and higher glass transition temperature (Tg, I19℃). Through copolymerization with styrene (St) or styrene-4,4‘-bismethacryloyloxydiphenylsulfone (BPSDMA), many properties of the copolymer such as refractive index, Abbe‘s number, strength, onset wavelength in the UV region and density were significantly modified. A copolymer resin with balanced properties between refractive index and dispersion was produced at the weight ratio of TDGDMA:St:BPSDMA (25:50:25), where nd20 and Abbe‘s number are 1.5815 and 36.5, respectively.     

SYNTHESIS OF BLOCK COPOLYMER FROM 5,6 -BENZO-2-METHYLENE-1,3-DIOXEPANE AND METHYL ACRYLATE VIA ATOM TRANSFER RADICAL POLYMERIZATION

Poly(methyl acrylate)-b-poly(5,6-benzo-2-methylene-1, 3-dioxepane) (PMA-b-PBMDO) was synthesized by two-step atom transfer radical polymerization (ATRP). Firstly, ATRP of methyl acrylate (MA) was realized using ethyl α-bromobutyrate (EBrB) as initiator in the presence of CuBr/2,2'-bipyridine. After isolation, poly(methyl acrylate) withterminal bromine (PMA-Br) was synthesized. Secondly, the resulting PMA-Br was used as a macromolecular initiator in theATRP of BMDO. The Structure of block copolymer was characterized by ~1H-NMR spectroscopy. Molecular weight andmolecular weight distribution were determined on a gel permeation chromatograph (GPC).     

含喹噁啉环高聚物金属络合物结构的X-射线光电子能谱XPS测定

<正> 本文报道聚[2,2′-(1,4-次苯基)-6,6′-氧双(3-苯基喹(口恶)啉)](简称PPQ)金属络合物的X-射线光电子能谱(XPS)研究,作为杂环高分子之一的PPQ与某些过渡金属(铑,铂)氯化物间生成的化合物具有很好的催化活性,因而探讨这种杂环高分子与金属氯化物间的直接键合作用及其结构对探明杂环高分子金属络合物的催化机理起重要作用。     

THE MECHANISM OF THE COPOLYMERIZATION OF BF_3-COMPLEXED ETHYL ACRYLATE WITH PROPYLENE

The copolymerization of BF_2-omplexed ethyl acrylate with propylene in the presence ofAIBN at 25℃was investigated. It was found that the rate of the copolymerization was propor-tional to the square root of the initiator concentration. The chain transfer agent CCl_4 greatly af-fects the inherent viscosity of the resulting copolymer. The smaller the dielectric constant of thesolvent, the greater the rate of copolymerization is. The equal concentration of the two monomersgive the maximum copolymerization rate. The ~1H-NMR and ~(13)C-NMR analysis indicated, when[EA.BF_2]/[EA.BF_2]+[P]>0.5, the resulting copolymer was the acrylate-rich random copoly-mer. Through the kinetic experiments we suggest that copolymerization follows the mechanismof the random copolymerization of the ternary complex with binary complex. When [EA.BF_3]/[EA.BF_2]+[P]<0.5, the resulting copolymer is always strictly alternating, and the alternatingcopolymerization follows the mechanism of the ternary complex homopolymerization. Usingthe homolog of the propylene, 1-pentene, we found that BF_3-complexed ethyl acrylate can forma ternary complex with 1-pentene identified by UV spectroscopy. This is a strong evidence forthe mechanism of ternary complex homopolymerizetion.     

THE EFFECT OF MONOMERS FEEDING METHODS ON EMULSION COPOLYMERIZATION OF VINYLIDENE CHLORIDE AND ACRYLATES

The emulsion copolymerization of vinylidene chloride (VDC) with methyl-methacrylate(MMA) and acrylonitrile (AN) was carried out by batch, seeded batch and semicontinuous pro-cesses,respectively. Significant differences were found in the physical and mechanical propertiesof the latexes and films, depending on the methods of monomer feeding. The results both intheory and experiments demonstrated that the copolymer composition and the length of the VDC sequences in the copolymer could be controlled by the modes of monomer feeding process.     

SOME ASPECTS OF MORPHOLOGIES AND INTERFACES IN COPOLYMER/HOMOPOLYMER BLENDS

Based on a series of morphological studies of blends of homopolymer (Homo) and a variety of block and graft copolymers (Cop), the nature of phase separation, interface, emulsification and inner morphology of copolymer-dispersed phase etc. in the blends are discussed. In the cases of Cop AB/Homo A/Homo B systems, in which one homopolymer forms matrix, it is observed that the dispersed homopolymer phase is exclusively associated with Cop AB, i.e. no Homo A-Homo B interface exists. This phenomenon is believed to be caused by minimizing the interfacial energy of the systems. Meanwhile, preferential solubilization or anchoring of the like chains of copolymer into homopolymer matrix leads to stabilization of the dispersed phase in the matrix. In addition, regular variation of the inner morphology of the dispersed copolymer phase with the composition and molecular parameters of the component polymers is observed. When the two components have comparable proportions, alternating concentric shells are the most common feature which is associated with minimizing the interfacial energy in the Cop/Homo systems.     

STUDY ON THE SYNTHESIS OF COPOLYMER CONTAINING N-SUBSTITUTED ACRYLAMIDE COMPONENT

In this paper the synthesis of linear and crosslinked N-substituted acrylamide copolymer is reported. In order to obtain the terpolymer with appropriate hydrophilicity, the conditions of aminolysis of St-MMA copolymer have been selected.It is shown that the copolymer with predictable hydrophilicity possesses good blood compatibility.     

KINETIC STUDY OF GAS-PHASE POLYMERIZATION OF PROPENE BY THE INHIBITION METHOD USING CARBON MONOXIDE

The inhibition method using CO to determine the active center concentration C~* in olefin poly-merization and the kinetics of gas-phase polymerization of propene were studied. The reliabilityof the method when used in gas-phase polymerization of propene is proved and the influencing fac-tor of the method is found to be the "repeating inhibition" of CO to the active centers. The C~*, the rate constant k_P and the activation energy were determined from the experimentalresults. We concluded that the C~* decreases with polymerization time and coincides with the decayrate of the polymerization.     

STUDIES ON THE KINETICS OF VINYL PHOTOPOLYMERIZATION INITIATED BY CONDENSED AROMATIC HYDROCARBON-ANILINE SYSTEMS

The photopolymerization of acrylonitrile and methyl methacrylate initiated by condensed aro-matic hydrocarbon-aniline systenis was studied at 25℃under irradiation of 365 nm wavelengthlight. From kinetic data the monomer exponent has been measured to be 1.1. Within the concen-tration of 10~(-4)--10~(-3)M, the aromatic hydrocarbon exponents changrd from 0.30 to 0.40, depedingon the values of molar extinction coefficient of the hydrocarbons at 365 nm (ε_(365)). The greater theε_(365), the Iower the exponents. The aniline exponents were measured to be in the range of 0.30--0.45. The aromatic hydrocarbon-aniline systems with the lower aniline exponent showed a lower ratioof the fiuorescence quenching of the hydrocarbon by aniline and by the monomer.