| Abstract: | The solid-state photoreactivity of a series of maleimides and bismaleimides is studied Various crystalline maleimides are found to dimerize on irradiation by ultraviolet light Based on this discovery, the photopolymerizability of the related bismaleimides in the crystalline state is examined. As a result it is found that some N,N,-alkylenebismaleimides polymerize into highly crystalline polymers. The polymers do not melt below their decomposition temperature (>300°C) and are practically insoluble in all solvents. The obtained irradiation products are different from the reaction products of the solution-phase photochemistry. Closely related bismaleimides, such as members of a homologous series, show substantial differences in their solid-state photochemical behavior; on excitation they either lead to polymers or are not reactive. This indicates that the solid-state photoreactivity of maleimides and bismaleimides is controlled by the geometry of their crystal structure. |
