Polymethylene Intermediates in Thermal and Photoinduced "Charge Transfer" Polymerization

当富电子烯烃和贫电子烯烃混合时，自发聚合反应是由四亚甲基中间体引发的，四亚甲基中间体可以是两性离子或双自由基。自发自由基共聚也同样被证明在二烯和烯烃的反应中与Diels-Alder环加成相竞争；这些聚合被认为是由2-己烯- 1,6 -二自由基或两性离子引发的。迄今为止，高功能化烯烃已被用于获得快速和清洁的反应。这些研究将扩展到常见的工业烯烃/烯烃反应，如苯乙烯和丙烯腈，以及二烯/烯烃反应，如异戊二烯/马来酸酐体系。此外，在每种情况下，将研究添加路易斯酸对提高电子贫烯烃的亲电性的影响。由适当取代的环丙烷和环丁烷生成的二自由基或两性离子将用于引发其他单体的聚合。这些系统的光化学行为将与热反应进行比较，并建立一个统一的机理图。本研究是首席研究员对自发电荷转移聚合机理的阐明的延续。这项研究的目的是了解在某些明确定义的条件下，一些单体对如何在缺乏通常需要的起始物质的情况下进行聚合。更好地控制聚合动力学和产生的结构是一个可能的结果。

Spontaneous polymerizations, observed when electron-rich and electron-poor olefins are mixed, are initiated by tetramethylene intermediates which can be either zwitterionic or diradical in nature. Spontaneous free-radical copolymerizations have similarly been shown to compete with the Diels-Alder cycloadditions in reactions of dienes and olefins; these polymerizations are proposed to be initiated by 2-hexene-l,6-diradicals or zwitterions. To date, highly functionalized olefins have been used to obtain fast and clean reactions. These investigations will be extended to common industrial olefin/olefin reactions, such as styrene and acrylonitrile, and diene/olefin reactions, such as the isoprene/maleic anhydride system. Moreover, the effect of added Lewis acid to increase the electronphilicity of the electron-poor olefin will be studied in each case. The generation of diradicals or zwitterions from suitably substituted cyclopropanes and cyclobutanes will be used for initiation of polymerization of other monomers. The photochemical behavior of these systems will be compared to the thermal reactions and a uniform mechanistic picture will be established. This study is a continuation of the principal investigator's elucidation of the mechanism of spontaneous charge- transfer polymerizations. This research has as its aim to understand how, under certain well-defined conditions, some monomer pairs can polymerize in the absence of the usually needed initiating substances. Greater control of the kinetics of polymerization and the resulting structures is a likely outcome.