Benzil/N,N-Dimethylaminoethyl Methacrylate System as Photoinitiator for Methyl Methacrylate Polymerization

Photopolymerization of MMA in bulk and an air atmosphere at 20°C was studied using the benzil/N,N-dimethylaminoethyl methacrylate (DMAEMA) combination as photoinitiator. The polymerization rate (R p) was proportional to the 0.3 power of the benzil concentration and the 0.6 power of the DMAEMA concentration. R p reaches a maximum and then declines as either the benzil concentration is increased (>0.03 M) or the DMAEMA concentration is increased (>0.01 M). The termination of polymerizatin was found to be bimolecular. DMAEMA can also act as a chain transfer agent; its chain transfer constant was evaluated to be 0.093. The methacrylate moiety of DMAEMA can participate in the polymerization process and cause crosslinking.