Photopolymerization of N-vinylcarbazole in dichloromethane in the presence and absence of free radical photoinitiators

Abstract

The photopolymerization of N-vinylcarbazole in dichloromethane was investigated, both in the presence and absence of free radical photoinitiators. The steric microstructure of the poly( N-vinylcarbazole) (PVK) samples produced was monitored as a function of temperature qualitatively, using 1H n.m.r. and quantitatively, using glass transition temperature measurements. The activation enthalpy and entropy differences between isotactic propagation when the previous diad was syndiotactic and syndiotactic propagation when the previous diad was isotactic (Δ H ‡ s/ i -Δ H ‡ i/ s ) and (Δ S ‡ s/ j -Δ S ‡ i/ s ) respectively were obtained from plots of log X i/ X s versus 1/ T for the free radically and cationically polymerized components of the PVK samples. Values for (Δ H ‡ s/ i -Δ H ‡ i/ s ) and (Δ S ‡ s/ i -Δ S ‡ i/ s ) of −2.65 kJ mol −1 and −11.7 J mol −1 grad −1 respectively were found for free radically polymerized fractions and +260 J mol −1 and −0.3 J mol −1 grad −1 for cationically polymerized fractions.