Studies on vinyl photopolymerization using a macromolecular C.T. Complex between poly(N-vinyl carbazole) and bromine as the photoinitiator

Photopolymerization of methyl methacrylate (MMA) was studied at 40°C using a macromolecular C.T. Complex between poly(N-vinyl carbazole) and bromine, expressed in brief as (PNVC–Br₂) complex, as the photoinitiator. Initiator exponent was 0.40 for PNVC–Br₂] ≤ 2.5 × 10^?3 mol L^?1 and practically zero for PNVC–Br₂] > 2.5 × 10^?3 mol L^?1. Monomer exponent in different diluent systems such as benzene, carbon tetrachloride, and acetone was close to 1.0. Low initiator exponent (<0.5) is explained on the basis of an initiator-dependent termination mechanism, in addition to the usual bimolecular termination. Analysis of kinetic data indicates that the initiator-dependent termination is primarily due to degradative initiator transfer and that due to primary radicals is considered inconsequential in view of monomer exponent being close to unity. The non-ideal termination process assumes over-whelming prominence at high PNVC–Br₂].