Chain transfer agents in cationic photopolymerization of a bis-cycloaliphatic epoxide monomer: Kinetic and physical property effects

摘要

Epoxides can undergo cationic photopolymerisation via two possible mechanisms: the active chain end (ACE) mechanism, where new monomer reacts with an epoxide cation attached to the end of the growing polymer chain, and the activated monomer (AM) mechanism, where the activated monomer cation is attacked by a mildly nucleophilic alcohol-type group (eg water or organic alcohol) and then the epoxide ring opens. Therefore the AM mechanism promoted chain transfer reactions, affecting both the rate of polymerisation and the structure of the polymer produced. The propagation rate constant for the AM mechanism has been measured to be about 5 times greater than that for the ACE mechanism.