Polymethylene Intermediates in Thermal and Photoinduced "Charge Transfer" Polymerization

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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.