Nonpolymerizable Monomers in Living Cationic Polymerization

活性阳离子聚合中的不可聚合单体

• 批准号: 9502777
• 负责人: Rudolf Faust
• 金额: $ 22.5万
• 依托单位: University of Massachusetts Lowell
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-07-01 至 1998-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9502777&HistoricalAwards=false
• 关键词: Nonpolymerizable; Monomers; Living; Cationic; Polymerization

9502777 Faust Kinetic and mechanistic studies on the additions of 1,1- diphenylethylene and related highly reactive but non- polymerizable monomers to living cationic polymers will be carried out. Conductance measurement and UV-vis spectroscopy combined with structure analysis will determine the kinetics and mode of addition, the extent of chain end ionization and dissociation. The kinetics of the addition of diphenylcarbenium ions to monomers will also be studied, and the absolute rate constants will be determined for free ions and ion-pairs. The results will be used in the synthesis of well-defined block copolymers by sequential monomer addition when the reactivity of the second monomer is higher then that of the first monomer. The method involves capping with a reactive but non-polymerizable monomer such as 1,1-diphenylethylene, followed by tailoring the Lewis acidity to the reactivity of the second monomer by the addition of titanium(IV) alkoxide, by replacing the Lewis acid with a weaker one or by the use of a common ion salt. Another objective of the proposal is to explore the synthesis of end-functional polymers by in-situ functionalization (end-quenching) of the living ends. The last objective of the proposal is to investigate the combination of living cationic and living anionic-group transfer polymerization for the synthesis of linear and hetero-arm star block copolymers. Two different methods are proposed based on 1,1-diphenylethylene capping; one based on site transformation and the other based on mutual annihilation of the living polymer cations and anions. %%% This research provides a novel approach to the synthesis of various well-defined polymers with precisely known architecture. Such polymers are needed to study the fundamental physical properties as a function of structure. ***

9502777 Faust 将进行 1,1-二苯基乙烯和相关高反应性但不可聚合单体向活性阳离子聚合物加成的动力学和机理研究。 电导测量和紫外-可见光谱与结构分析相结合，将确定添加的动力学和模式、链端电离和解离的程度。 还将研究二苯基碳鎓离子加成单体的动力学，并确定自由离子和离子对的绝对速率常数。 当第二单体的反应性高于第一单体时，结果将用于通过顺序添加单体来合成明确的嵌段共聚物。 该方法包括用反应性但不可聚合的单体（例如 1,1-二苯基乙烯）封端，然后通过添加钛（IV）醇盐来调整路易斯酸度以适应第二单体的反应性，并用较弱的一种或通过使用普通离子盐。 该提案的另一个目标是探索通过活性末端的原位官能化（末端淬灭）来合成末端功能聚合物。 该提案的最后一个目标是研究活性阳离子和活性阴离子基团转移聚合的组合用于合成线性和杂臂星形嵌段共聚物。 基于1,1-二苯乙烯封端提出了两种不同的方法；一种基于位点转换，另一种基于活性聚合物阳离子和阴离子的相互湮灭。 %%% 这项研究提供了一种新的方法来合成具有精确已知结构的各种明确的聚合物。 需要此类聚合物来研究作为结构函数的基本物理性质。 ***