Stepwise Photopolymerization of Bichromophoric Chains by Cycloaddition of Dibenz[b,f]azepine Groups

Abstract

ABSTRACT:Triplet-sensitized stepwise photopolymerization was carried out with a bichromophoric polymethylene compound. There is a critical chain length in this polymerization system, beyond which the linear oligomer becomes photopolymerized. The critical chain length P. (the degree of polymerization) was 3. The propagation rate of this polymerization decreased rapidly at a high conversion (>99.5%). The data obtained on this polymerization by laser photolysis was analyzed kinetically. The decrease of the concentration of the terminal pl).otoactive reactant, dibenz[b,flazepine (DBA) group, decreases both triplet-triplet (T-T) energy transfer efficiency and intermolecular reaction efficiency. As the chain length becomes longer, the intrinsic rate of deactivation of the terminal reactant exceeds the propagation rate.