电化学聚合漆酚铜配合物催化引发醋酸乙烯酯聚合的研究

将电化学聚合方法得到的聚合漆酚 (EPU)与氯化铜异丙醇溶液作用生成电化学聚合漆酚铜配合物(EPU Cu2 + ) .采用顺磁共振波谱 (ESR)、红外光谱 (FT IR)、XPS光电子能谱、原子发射光谱 (AES)、元素分析及AES等手段进行表征 ,确定该配合物的结构即每个铜离子与EPU分子中二个链节单元的羟基发生配位 .配合物中铜含量达 8 6 3% .实验表明 ,电化学聚合漆酚铜 (EPU Cu2 + )配合物膜在室温下的Na2 SO3水体系 (pH =7)中能催化引发醋酸乙烯酯 (VAc)按自由基加聚反应历程进行聚合 .讨论了温度、Na2 SO3浓度、VAc浓度和EPU Cu2 + 膜用量对聚合速率、诱导时间的影响 ,求得聚合速率的表达式Rp=0 0 7e- 2 82 5 RT[VAc]1 54[Na2 SO3]0 5,实验结果表明 ,EPU Cu2 + 配合物膜催化引发醋酸乙烯酯 (VAc)聚合的诱导期为 12 2s ,反应 2 4h后PVAc得率为79% , Mw =1 2 6× 10 6 , Mn=2 6 3× 10 5,多分散性系数为 4 79.     

原子吸收光谱法间接测定叶酸的含量

在pH5．0的NaOAc-HOAc缓冲溶液中，过量的硝酸银完全沉淀叶酸，用原子吸收光谱法测定剩余的硝酸银，间接计算出叶酸的含量。方法简单快速，回收率在98％～104％之间，相对标准偏差为2．4％。     

Determination of kinetic parameters of polymerizations by differential scanning calorimetry

Differential scanning calorimetry is well suited to record heat productions of chemical and physical processes as data for the following kinetic analysis. To obtain kinetic parameters of complex reactions, nonlinear optimization methods have to be used. Such complex reaction systems are polymerizations. We tried to evaluate measurements of the epoxy cure and the polymerization of β-propiolactame with simple and complex models. In both cases the simple models did not produce satisfactory results. But by using complex models a successful fitting of the measured data was possible. Our investigation shows that the combination of DSC and modern nonlinear evaluation methods presents a suitable tool for the kinetic investigation of polymerizations.     

铬系乙烯齐聚和聚合催化剂

综述了近年来国内外铬系催化剂的最新研究进展。介绍了该类催化剂齐聚和合的性能研究和应用，讨论了该催化剂长期引起争议的活性中心，活性价态，以及反应机理，并同时预测了铬系催化剂在工业和纳米技术方面的发展趋势。     

Group 4 complexes derived from o-carborane: synthesis, structures and ethylene polymerization properties

Nine thermally stable complexes (η⁵-Cp*)[η⁵-(C₅H₄)CMe₂CB₁₀H₁₀CR]MCl₂ (R=H and Me) and (η⁵-Cp*)[η⁵; η¹-(C₅H₄)CMe₂(CB₁₀H₁₀C)]MCl have been prepared via metathesis reactions of Cp*MCl₃ (M=Ti, Zr and Hf, Cp*=pentamethylcyclopentadienyl) with monolithium salts of (C₅H₅)CMe₂(CB₁₀H₁₀CR) (R=H and Me) and with dilithium salt of (C₅H₅)CMe₂(CB₁₀H₁₀CH), respectively. These compounds have been fully characterized by various spectroscopic methods and elemental analyses. All of the compounds except (η⁵-Cp*)[η⁵-(C₅H₄)CMe₂CB₁₀H₁₀CMe]HfCl₂ were additionally characterized by a single crystal X-ray diffraction study, establishing their monomeric bent metallocene structural feature with carborane acting as a substituent or an ancillary ligand. The titanium and zirconium complexes produce high-density polyethylenes with the activity range of about 10³-10⁴ g PE per mol of M bar h in the presence of modified methylaluminoxane cocatalyst.     

STUDY ON HIGHLY ACTIVE ZIEGLERNATTA CATALYSTS FOR POLYMERIZATION OF OLEFINS

In this paper, highly active Ziegler-Natta catalysts of MgCl_2 supported TiCl_4 for synthesis ofpolyolefins, using di-n-butyl phthalate (DNBP) as internal donor and diphenyl dimethoxyl silane(DPDMS) as external donor, have been prepared. The conditions controlling the treatment ofsupport were studied. The interactions of various components present in the catalysts and theirinfluences on catalytic performance were investigated. It is found that by using DNBP and DPDMSas internal and external donors together the polymer products with higher isotactic index can beobtained. Plausible structure model and mechanism were proposed.     

STUDIES ON THE POLYMERIZATION OF ACRYLONITRILE INITIATED BY METAVANADATE-CONTAININ G ANION EXCHANGER-THIOUREA REDOX SYSTEM

The polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by metavanadate-containing anion exchange resin (PV)-thiourea (TU) redox system at 20—40℃. has been investigated. The overall rate of polymerization (R_p) is given byR_p=1.92×10~4e~(-6.860/RT) [AN]~(1.2) [PV]~(0.44) [TU]~(1.0)[HNO_3]~(1.0)The kinetic parameters differed from those of V~(5+)-TU system indicated that the generation of the primary radicals is mainly a difffusion-controlled reaction. The effect of macromolecular field arisen from the polymer matrix exerts a great influence on the polymerization process.     

磺化聚苯乙烯／聚吡咯复合膜

磺化聚苯乙烯（ＳＰＳ）／聚吡咯（ＰＰｙ）复合膜是通过毗咯单体在ＳＰＳ基体中原位聚合方法制成的．用ＦＴＩＲ研究ＳＰＳ／ＰＰｙ复合膜分子间的相互作用，特别是ＳＰＳ中ＳＯ３阴离子在１２００ｃｍ－１不对称伸缩振动港带的分裂，说明了聚吡咯是以阳离子的形式作用于ＳＰＳ中ＳＯ３阴离子上，产生强的离子－离子相互作用．同时还研究了在复合过程中，引起ＳＰＳ基体的微区结构与性能的变化．ＳＰＳ由于吡咯单体的胀入和聚合，导致了ＳＰＳ微相分离，复合膜在动态力学性能测试中出现了两个Ｔｇ转变，分别在１２４和１４５℃．     

Titanium complexes bearing aromatic-substituted β-enaminoketonato ligands: Syntheses, structure and olefin polymerization behavior

A series of titanium complexes [(Ar)NC(CF₃)CHC(R)O]₂TiCl₂ (4b: Ar = -C₆H₄OMe(p), R = Ph; 4c: Ar = -C₆H₄Me(p), R = Ph; 4d: Ar = -C₆H₄Me(o), R = Ph; 4e: Ar = α-Naphthyl, R = Ph; 4f: Ar = -C₆H₅, R = t-Bu; 4g: Ar = -C₆H₄OMe(p); R = t-Bu; 4h: Ar = -C₆H₄Me(p); R = t-Bu; 4i: Ar = -C₆H₄Me(o); R = t-Bu) has been synthesized and characterized. X-ray crystal structures reveal that complexes 4b, 4c and 4h adopt distorted octahedral geometry around the titanium center. With modified methylaluminoxane (MMAO) as a cocatalyst, complexes 4b-c and 4f-i are active catalysts for ethylene polymerization and ethylene/norbornene copolymerization, and produce high molecular weight polyethylenes and ethylene/norbornene alternating copolymers. In addition, the complex 4c/MMAO catalyst system exhibits the characteristics of a quasi-living copolymerization of ethylene and norbornene with narrow molecular weight distribution.     

KINETICS OF SUSPENDED EMULSION POLYMERIZATION OF METHYL METHACRYLATE

The kinetics of suspended emulsion polymerization of methyl methacrylate (MMA), in which water acted as the dispersed phase and the mixture of MMA and cyclohexane as the continuous phase, was investigated. It showed that the initial polymerization rate (Rp0) and steady-state polymerization rate (Rp) were proportional to the mass ratio between water and oil phase, and increased as the polymerization temperature, the potassium persulphate concentration ([I]) and the Tween20 emulsifier concentration ([S]) increased. The relationships between the polymerization rate and [I] and [S] were obtained as follows: Rp0 ∝ [I]0.73[S]0.32 and Rp ∝ [I]0.71[S]0.23. The above exponents were close to those obtained from normal MMA emulsion polymerization. It also showed that the average molecular weight of the resulting poly(methyl methacrylate) decreased as the polymerization temperature, [I] and [S] increased. Thus, MMA suspended emulsion polymerization could be considered as a combination of many miniature emulsion polymerizations proceeding in water drops and obeyed the classical kinetics of MMA emulsion polymerization.