偏氟乙烯／三氟乙烯共聚物介电松弛的结晶度效应

用改进的介电松弛谱仪（精度２‰）测定了ＶＤＦ／ＴｒＦＥ（７／２７、６５／３５、５２／４８ｍｏｌ％）共聚物溶液成膜、液氮淬火、熔融慢冷和热处理试样在－１２０—１３０℃、１０－２一１０４Ｈｚ范围的复数介电常数．介电松弛研究结果显示低结晶度的淬火试样较高结晶度的熔融慢冷和热处理试样的Ｔｃ高．结晶度上升，居里点处的介电常数增大．室温以下的介电频率谱分别由代表非晶区分子运动的β松弛（低频部）和局域运动的γ松弛（高频部）叠合而成．随结晶度提高，β松弛峰减小，γ松弛峰增大；非晶松弛强度减弱．晶区松弛强度增强．     

RECTIFYING EFFECT OF POLYANILINE(PANI)/N-TYPE POROUS SILICONE HETEROJUNCTION*

Heterojunctions between polyaniline (PANI) and n-type porous silicon (PS), Al/PS-PANI/Au cell,were fabricated, and the rectifying parameters of this heterojunction diode were measured as a function of thepreparation conditions of PANI and PS, the electronic structure of PANI as well as cell structure. Therectifying parameters of Al/PS-PANI/Au cell were determined to be γ= 1 .8×10~1～ 1 .0×10~5 for the rectifyingratio at 3V, n = 3 ～12 for the ideal factor,j_0 = 8.0×10~(-5)～5.6×10~(-2) mA/cm~2 for the reversed saturated currentdensity, and φ_b = 0.67～ 0.83 V for the barrier height, respectively. The best rectifying heterojunction diodemade between PANI and n-type PS with higher rectifying factor (γ= 1 .0×10~5 at 3V ), output current (>1500mA/cm~2 at 3V) and lower ideal factor (n = 3.3) was obtained by preventing the oxidation of PS beforeevaporating Al electrode.     

CONFORMATION AND CHAIN PACKING STRUCTURES OF POLY (ρ-PHENYLEN BENZOBISTHIAZOLE) BY MOLECULAR SIMULATION*

The conformation, the chain packing stabilization and the unit cell modeling of poly(p-phenylene benzobisthiazole) have been investigated by using molecular simulation techniquein the present work. A coupling behaviour of σ-bond rotations at either side of the pheny-lene ring or the heterocyclic ring was found surely to exceed a length of the repeat unit ofthe polymer chain. For a single chain model, the stable torsion angle of the repeat resultedat 14°. In the crystalline cell minimization, the dihedral angle along the polymer chaincould even be stabilized in various values. It therefore indicates that the intermolecularinteraction does play a considerable role for this polymer forming the conformation. Ac-cording to cohesive energies calculated for these unit cell models, the torsion angle in themost stable crystalline cell is 0°. When the chains packing together, there exist so manyenergy stable wells along the chain axis 0.35--0.36nm apart from neighbouring chains.Most of the unit cells have quite closed cohesive energies. These factors thus cause thedifficulty of forming an unique perfect crystalline structure of the polymer. The presentstudy suggested a number of reasonable unit cells, and the most stable crystalline structurefor this polymer that is monoclinic, non-primitive unit cell.     

EFFECT OF SOLVENT COMPOSITION ON THE SULFONATION DEGREE OF POLY(PHENYLENE OXIDE) (PPO)

This paper investigates the possibility of attaining sulphonated poly(phenylene oxide) (SPPO) with a relativelyhigher sulfonation degree. To achieve this aim, the approach we adopt is to improve the solubility of the final product in themixed solvent so that the sulfonation may take place between the bulk solutions and PPO powders even at higher sulfonationdegree. It is shown that the addition of a proper amount of dimethyl formide (DMF) to the conventional PPO-chloroformsystem can actually enhance the sulfonation effect. The solvent composition is then correlated with the sulfonation degreebased on the solubility parameters. It is interesting to find that solubility parameters between the mixed solvent and theprecipitated products keep an approximately unchanged value at about 4.9, which is just equal to that when pure chloroformis used, though the solubility parameters of both solvents increase with the content of DMF in solution. This may be the mainreason why the addition of DMF can reduce the precipitation and improve the ion exchange capacity (IEC) of SPPOpolymer.     

STUDY ON THE SEQUENCE STRUCTURE OF BUTADIENE-STYRENE RUBBER BY ~(13)C-NMR METHOD V.CALCULATION METHOD OF DIAD COMPOSITION

The calculating equations which could be used to obtain diad composition from the peakintensities of carbon spectra were derived. The result of the microstructure calculated from thediad compositions was in good agreement with that obtained through IR or ~1H-NMR measurement.     

RING-OPENING COPOLYMERIZATION OF DL-LACTIDE AND POLY(ETHYLENE GLYCOL) INITIATED BY LANTHANUM ACETATE AND APPLICATION OF THE COPOLYMER AS MATRIX OF MICROSPHERES CONTAINING VIBRIO CHOLERA ANTIGENS*

Poly-dl -lactide-poly(ethylene glycol ) (PELA) triblock copolymers were synthesized withlanthanum acetate as the initiator. PELA microspheres with entrapped Vibrio Cholera antigen and outermembrane protein (OMP) were prepared by a double emulsion W/O/W based on solvent extraction methods.The obtained microspheres showed smooth and spherical surface and their size varied between 0.5 and 5.0μm, which are suitable for oral targeting delivery system. The distribution tests in rabbits and mice throughscanning electronic micrography and fluorescence microscope indicated that microspheres have successfullyreached the immunization-related tissues, such as the liver, spleen and intestinal peyer's patches, followingoral administration. The PELA microspheres were also evaluated as an efficient antigen delivery system byenhancing a higher protective ratio against live Vibrios Cholera.     

EFFECT OF CHEMICAL STRUCTURE OF SULFOXIDE GRAFTED POLY (VINYL ALCOHOL) ON GAS PERMEABILITY

The effects of chemical structure, i. e. side chain structure and their contents, on thepermeability of pure SO_2, N_2 and their mixture gases for the sulfoxide grafted poly (vinylalcohol) (RVSO-PVA) membranes have been investigated:where R=Me, Et, Pr, t-Bu and Ph. It was notable that introduction of sulfoxide group intoPVA side chain greatly enhanced the permselectivity of sulfur dioxide. SO_2 permeability andseparation factor of these polymers increased markedly as the size of side chain increased. Thesulfoxide content of the polymer also played an important role in the pure and mixture gasespermeation. Some explanations have been made to interpret this unique gas separation behaviour.     

PHASE STRUCTURE AND COMPATIBILITY OF LADDERLIKE POLYPHENYLSILSESQUIOXANE (PPSQ)/POLYCARBONATE (PC) BLENDS PREPARED BY SOLUTION CASTING*

Blends of PC and PPSQ (A) with high M_w and good ladderlike regularity or PPSQ(B) withlow M_w and more defective Si-atoms in its structure have been prepared by solution casting. Thedispersed spheres (PPSQ(A)-rich) are unevenly dispersed in the continuous PC-rich phase and there isno phase-inversion as PPSQ(A) content increases when the percentage of PPSQ(A) is not more than70%. PPSQ(B)-rich spheres are evenly dispersed in the continuous phase (PC-rich) and phase-inversion occurs when PPSQ(B) percentage is up to 70%. T_g of PPSQ(A)/PC or PPSQ(B)/PC at somecompositions are lower than that of pure PC due to the enlarged free-volume of PC-rich phase becausesome spheres of rigid PPSQ chains are included in the PC-rich phase. PC and PPSQ(A) or PPSQ(B)are partially compatible. The compatibility of PC and PPSQ(B) is better than that of PC and PPSQ(A)with high M_w and good ladderlike regularity. Heat history has some influence on the T_gs andcompatibility of PPSQ(A)/PC and PPSQ(B)/PC blends.     

THE EFFECT AND FUNCTION OF AliBu_2OR'''' ON BUTADIENE-PROPYLENE ALTERNATING COPOLYMERIZATION CATALYZED BY VO(OR)_2Cl-AIiBu_3 SYSTEM

Four kinds of AliBu_2OB' with different R' were synthesized. The effect of AliBu_2OR'/AliBu_3 mole ratio on the conversion, the [η] of copolymer and catalytic efficiency were studied. The conversion was increased obviously and the catalytic efficiency was 2.7 times higher than before. The effect of the amount of AliBu_2OR' on the valence state of vanadium ion and the change of the valence state of vanadium ion with reaction temperature and time were studied. The VIS and IR spectra of the trinary-component catalyst system were measured. The model of active center including AliBu_2OR' was proposed. The function of AliBu_2OB was explained.     

CLOUD POINT CURVES OF POLY(ETHYLENE GLYCOL)/POLY(PROPYLENE GLYCOL) MIXTURES AND THEIR THERMODYNAMIC EXPLANATION

In the study of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG) mixtures not only a bimodal shape but also a reverse trend of the dependence on molecular weight of the cloud point curves were observed.This trend indicates that the miscibility of the studied mixtures decreases as the molecular weight of one component decreases. The excess volumes of the mixtures show that the interaction parameter between two components decreases at first and increases after passing a minimum as the concentration of one component increases. This supports the explanation of Koningsveld on the bimodal shape of cloud point curves. Based on a binary interaction model a formula was derived revealing that the interaction between PPG and the end group of PEG and the hydrogen bonding interaction between ether and hydroxy end group inner or inter PEG molecules are not favorable for mixing. The latter interaction is an "attractive" force in PEG molecules. The two interactions are responsible for the observed abnormal dependence.     

PREPARATION OF PERFLUOROOCTANOYL-MODIFIED POLY(VINYL-ALCOHOL)S AND THEIR ADSORPTION AT AN AIR-WATER INTERFACE

Perfluorooctanoyl modified poly(vinyl alcohol)s (FPVA) were prepared by means of substituting a small amountof hydroxyl groups on the backbone of poly(vinyl alcohol), for which the initial degree of polymerization is equal to 1750.The substitution extent, defined by the number of substituting units in a chain, for the four FPVA samples was in the range of0.5-5 perfluorooctanoyl groups per chain. The FPVA samples with the highest substitution extent still had good solubility inwater. It was shown by experimental measurement at 30.0±0.1℃ that the surface tension of the aqueous solution of thehighest substituted FPVA decreased to 16.6 mN/In at a higher concentration, e.g about 0.1 g/mL. Obviously,macromolecules of FPVA exhibit a very strong tendency to adsorb at the air-water interface, because the hydrophobicperfluorooctanoyl groups in FPVA have a very high surface activity as they are in small molecular fluorinated surfactants.The chain conformation of such a model polymer adsorbed on the air-water interface was also discussed.     

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.     

SYNTHESIS AND CHARACTERIZATION OF FOUR-ARMED BLOCK POLY(STYRENE-b-p-NITROPHENYL METHACRYLATE)PREPARED BY THE ATRP METHOD*

A novel tetrafunctional initiator, C [CH_2O (CH_2)_3 OOCCH(Br)CH_3]_4 (1), was synthesized through the reaction oftetraol with α-bromopropionyl chloride, and then was used as initiator of atom transfer radical polymerization (ATRP) in thepreparation of 4-armed polystyrene (PSt) with narrow polydispersity. The structure, molecular weight and molecular weightdistribution (MWD) of each arm were studied by ~1H-NMR and GPC data of hydrolyzed products of the 4-armed PSt. TheATRP of St using 1/CuBr/bpy as initiator system is of "living" character based on the following evidence: narrow MWD,constant concentration of chain radical during the polymerization, control of molecular weight by the molar ratio of monomerconsumed to 1. The 4-armed poly(St-b-p-nitrophenyl methacrylate) [poly(St-b-NPMA)] was prepared by the ATRP ofNPMA using 4-armed PSt with terminal bromine as the initiator, and characterized by FT-IR, ~1H-NMR spectra and GPCcurves. The micelles with PSt as core, and PNPMA as shell were formed by dropping DMSO into a solution of 4-armedpoly(St-b-NPMA) in DMF, as proved by laser light scatter (LLS) method.     

SYNTHESIS,CHARACTERIZATION AND OPTICAL PROPERTIES OF THE COPOLYMERS OF C_(60) AND 1-PHENYL-1-PROPYNE*

While WCl_6-Ph_4Sn fails to polymerize 1-phenyl-1-propyne (PP) at room temperature, highmolecular weight (M_w up to 410×10~3) polymers are obtained in high yields (up to 80%) when thepolymerizations of PP are carried out in the presence of C_(60) using the W catalyst under the same conditions.The polymers are soluble in common organic solvents such as THF, chloroform, and toluene. Molecularstructures of the polymers are characterized by FT-IR, UV, NMR, GPC and XRD, and it is found that C_(60) iscopolymerized with PP. Thus C_(60) plays the dual roles of comonomer and cocatalyst in the polymerizationreaction. C_(60) contents of the copolymers can be easily changed by varying the C_(60) amounts in the feedmixtures. The copolymers effectively limit strong 532 nm laser pulses, whose limiting performance issuperior to that of parent C_(60).     

ROLE AND IMPORTANCE OF RADIUS OF GYRATION OF CHAINS IN THE MELT IN THE CRYSTALIZATION OF POLY(1-BUTENE)

Crystallization in polymer systems actually is a process that transfers the entangled melts into a semi-crystallinelayered structure. Whether or not a chain disentangles may result in different crystallization mechanism. When compared tothe crystal thickness (d_c), the volume occupied by the chain in the melt, i.e., the radius of gyration (R_g), plays a veryimportant role in polymer crystallization. When d_c≤R_g, crystallization does not necessitate a chain disentangling. Theentanglements are just shifted into the amorphous regions. However, as d_c>R_g, i.e., as the crystal thickness ges larger thanthe radius of gyration of the chain in the melt, it becomes necessary for a chain to disentangle. Then a change ofcrystallization mechanism occurs. Such change has been experimentally observed in the crystallization of poly(1-butene). Achange in the crystal morphologies from spherulite to quadrangle, is seen via PLM, as crystalliation temperatures increase.Even more, such a change is molecular weigh dependent and shifts to lower temperature as molecular weigh decreases.There exists a jump of crystal thickness and crystallinity associated with morphological change, as seen via SAXS. A changeof crystallization kinetics and crystallinity is further evidenced via dilatometry. The unique feature of P1b crystallization hasbeen discussed based on the radius of gyration of chain in the melt (R_g), and very good agreement is obtained.     

光活性聚甲基丙烯酸三苯甲酯链结构的研究——PTrMA的~(13)C液体和固体NMR谱

<正> 80年代出现的光活性高聚物—聚甲基丙烯酸三苯甲酯(PTrMA)是由非手性单体经不对称阴离子聚合得到的。近年来,PTrMA作为手性固定相在分离手性化合物方面得到了越来越多的实际应用。由于聚合物侧基上的三个苯基产生的大位阻,使它具     

SELF-ASSEMBLED MICRO-DOMAINS ON THE UPPERMOST SURFACE OF FLUORINATED POLY（CARBONATE URETHANE）S WITH FLUORINATED SIDE CHAIN ATTACHED ON HARD SEGMENTS

The surface phase separated structure of polyurethanes is always desired due to the advantage of better biocompatibility, compared with the homogeneous one. The key issue is how to control and characterize the surface morphology. In this work, we report the uppermost surface morphology of fluorinated poly(carbonate urethane)s with fluorinated side chains attached to hard segments as studied by AFM, XPS and contact angle measurement. A self-assembled micro-domain with the fluorinated side chain standing up on the uppermost surface has been proposed for polyurethane with higher fluorinated content, based on the result obtained     

INFLUENCE OF TRACES OF WATER ON THE SYNTHESIS AND ELECTROLUMINESCENCE PROPERTIES OF POLY(2-METHOXY, 5- (2'''' -ETHYLHEXYL OXY)- 1, 4-PHENYLENE VINYLENE)

It was found that traces of water in the reaction medium would result in a great increase of gel and a decrease ofmolecular weight of the poly(2-methoxy, 5-(2'-ethylhexyloxy)-1, 4-phenylene vinylene) during the polymerization, whichultimately led to inferior film qualities and device properties. The device (ITO/PEDOT/MEH-PPV/Ba/Al) with MEH-PPVprepared under dry conditions has an external quantum efficiency of above 2.0%.