PHOTOPOLYMERIZATION OF METHYL-METHACRYLATE USING MORPHOLINE-BROMINE CHARGE-TRANSFER COMPLEX AS THE PHOTOINITIATOR

Photopolymerization of methyl methacrylate (MMA) was kinetically studi ed using near UV/ visible light at 40 degrees C and by employing the m orpholine (MOR)-bromine (Br-2) charge transfer (CT) complex as the pho toinitiator. The rate of polymerization (R-p) was dependent on the mor pholine:bromine mole ratio; the 1:2 (MOR-Br-2) CT complex acted as the latent initiator complex C which underwent further complexation with monomer molecules to give the actual initiator complex, I. Using a 1:2 (MOR-Br-2) CT complex as the latent initiator, the initiator exponent for bulk photopolymerization of MMA was 0.08 and the monomer exponent determined from studies of photopolymerization in a carbon tetrachlor ide diluted system was 1.20. Benzoquinone behaved as a strong inhibito r and the polymers tested positive for the incorporation of bromine at oms as end groups. Polymerization followed a radical mechanism. Kineti c non-ideality was revealed by low (<<0.5) initiator exponent and a mo nomer exponent of greater than unity; it was explained in terms of pri mary radical termination. (C) 1998 Elsevier Science Ltd. All rights re served.