Photocrosslinking of polyimide containing benzophenone unit: The effects of polymer compositions on reaction rates and polymer coil dimensions due to the reaction in solution.

Abstract

The kinetic parameters and the changes in polymer coil dimensions during the competitive intra- and intermolecular photocrosslinking reactions in THF solution depend on the number of alkyl substituents in the diamine component and the amount of benzoph- enonetetracarboxylic dianhydride(BTDA) in polyimide. When a second orth-alkyl substituent is introduced, the quantum yield for intramolecular reaction, including some side reaction with solvent increases and oppositely the quantum yield for intermolecular reaction decreases. The magnitude of 1/2 and Mw is related to the degree of the competition between intra- and intermolecular crosslinking. The contraction ratio, g, of polymer coils decreases smaller as the amount of BTDA in the polyimide increases.