聚烯烃/聚酯(聚醚)共聚物的合成及应用

本文首先详细评述了聚烯烃/聚酯(聚醚)共聚物的合成方法:聚合机理转换法和聚合物偶联法.其中,聚合机理转换法又分为:(1)链转移剂控制烯烃聚合/阴离子开环聚合;(2)链转移剂控制烯烃聚合/配位-插入开环聚合;(3)烯烃阴离子活性聚合/阴离子开环聚合;(4)烯烃阴离子活性聚合/配位-插入开环聚合;(5)叶立德活性聚合/配位...     

水相配位催化烯烃聚合的新进展*

水相催化研究已经成为近年来化学反应研究的热点课题.烯烃聚合领域中水相自由基乳液聚合和悬浮聚合等方法早已工业化,而前过渡金属烯烃聚合催化剂对水气敏感,水相烯烃配位聚合发展缓慢.低亲氧性、高活性的后过渡金属烯烃聚合催化剂的出现使水相催化成为可能.本文综述了后过渡金属催化剂水相催化烯烃配位聚合的一些新进展,内容包括乙烯、α-烯烃、环烯烃、二烯烃的聚合反应和环烯烃的开环聚合反应以及CO/烯烃的共聚反应等方面.     

[N,N]-二齿镍配合物催化烯烃聚合

烯烃聚合催化剂的设计是烯烃配位聚合领域的一个核心科学问题,通过设计合成精确结构的催化剂可以有效地调控催化聚合性能以及聚合产物的结构.后过渡金属催化剂由于其易调变性、对聚合产物支化结构的可控性及对极性单体的容忍性,在烯烃聚合领域引起了广泛的关注.本文介绍了近年来本课题组在[N,N]-二齿镍烯烃聚合催化剂设计方面的研究进展,包括四元环的中性脒基镍催化剂、五元环的-二亚胺镍催化剂、2-胺基吡啶和-胺基亚胺系列镍催化剂,以及六元环的-二亚胺和苯胺基亚胺镍催化剂在烯烃聚合的应用.通过优化后过渡金属镍催化剂结构,可成功实施烯烃活性聚合.     

烯烃高效催化剂及聚合与共聚合的研究

为中山大学高分子研究所烯烃配位聚合研究室在高效Ziegler-Natta催化剂、茂金属催化剂烯烃聚合与共聚合方面部分研究工作的概述。重点叙述了催化剂的设计、过渡金属配合物配体结构及聚合条件对乙烯、丙烯、1-丁烯、丁二烯、苯乙烯等烯烃单体聚合及共聚合活性以及聚合产物结构和分子量的影响。     

烯烃阴离子聚合发展60年的现状与释疑的努力

简述了依据阴离子聚合基本理论实施的反应挤出聚合,表述了其在工业应用领域的价值以及对阴离子聚合理论的贡献。回顾了烯烃阴离子聚合发展60年的历程,特别是近10年国内外烯烃阴离子活性聚合领域绝大部分的研究。在此基础上,列举了迄今为止烯烃阴离子聚合领域遗留的5大悬疑与2大发展瓶颈,引用本研究团队近20年来的研究,分别就阴离子聚合的释疑与突破进行了阐述。     

新型后过渡金属烯烃聚合催化剂－－镍系烯烃聚合催化剂*

镍系烯烃聚合催化剂是近年来受到广泛关注的一类新型催化剂,是配位催化研究的热点之一。这类催化剂具有高催化活性、单活性中心和良好的分子剪栽性,可以在分子层次上实现烯烃聚合的分子设计与组装。本文介绍了镍系烯烃聚合催化剂的发展和研究概况,并评述了聚合特性及最新研究进展。     

烯烃聚合单组分稀土催化剂

概述了烯烃聚合单组分稀土催化剂在烯烃均聚、烯烃与烯烃、苯乙烯共聚及烯烃与极性单体共聚等研究领域的最新进展。     

烯烃聚合钯催化剂研究进展

综述了烯烃聚合钯催化剂的研究进展,烯烃聚合钯催化剂的配体类型有膦配体、氮配体、碳配体、氧配体、氮-氧配体、膦-氧配体、氮-膦配体等。与齐格勒-纳塔催化剂和茂金属催化剂相比,烯烃聚合钯催化剂具有高催化活性、单活性中心和良好的分子剪裁性等优点,可在分子层次上实现烯烃聚合的分子设计与组装;与铁、钴、镍等后过渡金属催化剂相比,烯烃聚合钯催化剂具有反应条件较温和、催化活性和立体选择性较高的优势。     

新型后过滤金属烯烃聚合催化剂——镍系烯烃聚合催化剂

镍系烯烃聚合催化剂是近年来受到广泛关注的一类新型催化剂，是配位催化研究的热点之一。这类催化剂具有高催化活性、单活性中心和良好的分子剪栽性，可以在分子层次上实现烯烃聚合的分子设计与组装。本文介绍了镍系烯烃聚合催化剂的发展和研究概况，并评述了聚合特性及最新研究进展。     

新型烯烃聚合催化剂研究进展

由于过渡金属催化剂在烯烃聚合方面具有高活性和良好的分子剪裁性,通过调节催化剂的微结构或温度、压力等聚合环境的变化,可以在分子层次上实现烯烃聚合物的分子设计与组装,实现聚合物物理性质的调控,最近引起了人们的广泛关注。本文介绍了过渡金属催化剂的合成及其负载化,水相烯烃聚合及活性聚合等方面的研究进展。     

Steady State Simulation of Ethylene Polymerization Using Multiple-Site Coordination Catalysts

Summary: Simulation models are important tools for the development and optimization of polymerization processes because they can describe catalyst performance and polymer properties as a function of polymerization kinetics and process conditions. As the polyolefin industry moves towards the production of resins with more complex microstructures, these models become essential for process understanding and product design. A simulation model has been developed for the polymerization of ethylene in a process with n reactors working in series. The model can predict raw material conversions and product properties like the molecular weight distribution (MWD) coupled with short chain branching distribution (SCBD), melt index, density and fluff morphology. Model parameters have been obtained from laboratory data. The model predictions are in good agreement with experimental results.     

Dynamic Monte Carlo Simulation of Olefin Polymerization in Stopped-Flow Reactors

Stopped-flow reactors are very useful to estimate olefin polymerization rate constants and to investigate particle morphology development. Because the residence time in these reactors is comparable to the life time of the polymer chains, very narrow molecular weight distributions are obtained and the number average molecular weight is proportional to reactor residence time. In this case, traditional models for olefin polymerization in industrial reactors can not be applied. In this contribution, we derived analytical solutions and performed Monte Carlo simulations to describe the time evolution of the molecular weight distribution of polyolefins made with single- and multiple-site catalysts in stopped-flow reactors.     

RAFT Polymerization in Bulk and Emulsion

Detailed models of the RAFT polymerization in both non-segregated (bulk) and segregated (seeded emulsion) systems are presented. It is shown that satisfactory agreements between experiments and models can be achieved, and that effects such as inhibition and retardation, or the polymerization behavior at high conversions can be readily explained. In all cases the model parameter fitting has been minimized, being mostly limited to the rate coefficients of the addition/fragmentation reactions in the RAFT polymerization. Therefore, such models are believed to be invaluable tools towards a deeper understanding of the main phenomena underlying RAFT polymerization.     

Model for Kinetics of Vinyl Chloride Polymerization

This paper gives a critical review of recent models for the polymerization of vinyl chloride. In solution and bulk polymerization the effect of eventual degradative chain transfer to monomer, addition of chain transfer agents, and precipitation of polymer is discussed. A model for emulsion polymerization is described which includes particle formation and kinetics of polymerization where especially desorption and reabsorption of radicals in the particles are included.     

甲基丙烯酸甲酯聚合动力学和分子量模型及仿真

考虑甲基丙烯酸甲酯聚合过程中体积收缩，反应物和生成物的浓度变化，以及由于凝胶、玻璃化和笼闭等效应对各速率常数和物性参数的影响，从基元反应和物料平衡出发，推导了半间歇，有链转移剂参与情况下的聚合动力学和分子量模型。用模型仿真计算了聚合温度、引发剂、溶剂和链转移剂的种类和浓度等对甲基丙烯酸甲酯聚合动力学和聚合过程中分子量变化的影响规律，并与实验和文献数据进行比较。     

Compressible models of equilibrium polymerization

Flory-Huggins-type models of equilibrium polymerization are extended to describe compressible systems and, hence, the pressure dependence of thermodynamic properties. The theory is developed for three different mechanisms of equilibrium polymerization (the free association, monomer-activated polymerization, and chemically initiated polymerization models). In contrast to previous approaches for describing the pressure dependence, the theory delineates the thermodynamic consequences of the size disparities between solvent molecules, unpolymerized monomers, and the monomers within polymers. Basic thermodynamic properties (the extent of polymerization, density, heat capacities C(P) and C(V), etc.) are calculated analytically as functions of pressure, temperature, and composition of the associating species. Illustrative calculations refer to systems that polymerize upon cooling and demonstrate general agreement with numerous experimental trends. Comparisons with results from other theories are also discussed.     

茂金属催化乙烯聚合反应动力学

以茂金属化合物[(CH3)2C(η－C5H3）（η－C9H6）]ZrCl2为主催化剂，甲基铝氧烷MAO为助催化剂催化乙烯聚合，对不同的反应条件下（如温度，铝锆摩尔比）聚合反应的动力学进行了研究，并根据此聚合反应体系的动力学特点及考虑到活性中心的再活化，在分析和研究以往的动力学模型的基础上，对烯烃均相聚合动力学反应作了一些假定，建立了动力学模型，用模型对实验数据进行了拟合，结果表明与实验数据相吻合，可以认为，在该聚合反应体系中，确实存在铝氧烷的再活化作用，根据模拟拟合得到了聚合反应的动力学参数。     

Effect of polymerization rate on the polyethylene structure obtained with a high activity catalyst system

The effect of polymerization rate on polyethylene structure, using magnesium reduced titanium tetrachloride catalysts together with the usual aluminium alkyl activator, is described. It is shown that the polymer bulk density and the nascent super-molecular structure formed during ethylene polymerization depends upon the rate of polymerization. The results indicate that, with increasing polymerization rate, the catalyst active sites produce polymer with different densities. One possible explanation for this phenomenon lies in considering the inhibition of crystallization by high polymerization rates. Experimental results on different polymer morphologies are discussed. Finally models for the structure of polymer particles are considered briefly.     

New Kinetic Model of Ethene Polymerization with Cp2ZrCl2 /MAO Catalyst

The kinetics of ethene polymerization catalyzed by Cp₂ZrCl₂ /MAO is studied. A detailed look is taken at the different kinetic models used to describe the polymerization process. Also, a new model was developed on the basis of previous work. The new model takes both the active‐sites mechanism and the reactivation effect of MAO into account. Better agreement between the experimental data and the fitting profile was achieved by applying the new model, when compared with the results from older models. A plausible mechanism of polymerization is outlined.