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

The effects of chain transfer agents (CTA) on cationic ring-opening polymerization of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate (EEC) were explored. EEC was polymerized in the presence of various CTAs, and epoxide conversions monitored via Raman spectroscopy. Polymer films were prepared and analyzed by dynamic mechanical analysis. Many of the organic alcohols studied greatly enhanced epoxide polymerization rates and conversion levels. The gel fraction of polymer specimens decreased rapidly with increasing amounts of octanol (gel fraction >90% up to 0.3 equiv OH) but remained high with increasing amounts of 1,2-propanediol (gel fraction >90% up to 0.6 equiv OH). Increasing the size of primary alcohols had little effect on the polymerization rates and conversions. The polymerization rate decreased with increasing alcohol substitution (1 degrees>2 degrees>3 degrees). Acidic alcohols had very low impact on conversion and polymerization rates relative to the neat epoxy resin. The glass transition temperature was inversely related to the size and amount of CTA. (c) 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013, 51, 2058-2067