Cationic Polymerizations in Supercritical Carbon Dioxide

碳阳离子聚合广泛用于大批量工业过程（例如丁基橡胶和异丁烯工业）。 这些聚合反应通常在有毒的氯化烃溶剂中进行，每年有数千磅的溶剂最终排放到大气中。 该项目旨在研究用环境中性、廉价的二氧化碳替代这些污染溶剂作为弗里德尔-克拉夫茨酸介导聚合的通用溶剂的可能性，除此之外，还研究一般弗里德尔-克拉夫茨酸催化反应的通用溶剂。 第一个具体重点是证明在碳阳离子聚合和共聚中有毒溶剂可以被超临界二氧化碳取代，并阐明这些过程的范围和基本原理。 随后将探索弗里德尔-克来福特酸催化反应，如烷基化、磺化、乙酰化等。将探讨超临界二氧化碳中压力、温度和试剂浓度的影响。 聚合研究的初始阶段将涉及常见单体（异丁烯、苯乙烯及其衍生物，以及共轭二烯，如异戊二烯）、共引发剂和少量添加剂（共溶剂、质子陷阱、电子供体和盐）。

Carbocationic polymerizations are used extensively in large volume industrial processes (for example, butyl rubbers and isobutylene-based industries). These polymerizations are commonly carried out in toxic chlorinated hydrocarbon solvents, many thousands of pounds of which end up yearly in the atmosphere. This project is an investigation into the possibility of replacing these polluting solvents with the environmentally neutral, inexpensive carbon dioxide as the all-purpose solvents for Friedel-Crafts acids mediated polymerizations, and beyond these, to Friedel-Crafts acid catalyzed reactions in general. The first specific thrust will be the demonstration that the toxic solvents can be replaced with supercritical carbon dioxide in carbocationic polymerizations and copolymerizations, and to elucidate the scope and fundamentals of these processes. This will be followed by explorations into Friedel-Crafts acid catalyzed reactions, such as alkylation, sulfonation, acetylation, etc. The effects of pressure, temperature, and reagent concentrations in supercritical carbon dioxide will be explored. The initial phase of the polymerization studies will concern common monomers (isobutylene, styrene and its derivatives, and conjugated dienes such as isoprene), coinitiators, and small amounts of additives (cosolvents, proton traps, electron donors, and salts).