Photopolymerization of methyl methacrylate using triethylamine-nitrobenzene complex as photoinitiator

Photopolymerization of methyl methacrylate in bulk and in solution at 40° using triethylamine nitrobenzene (TEA-NB) complex as photoinitiator was studied kinetically. Initiator order x, given by the relation R_pα([TEA][NB])^x, was 0.28 for [TEA][NB] < 25 × 10 ^?8 mol² · l^?2; for higher values of [TEA][NB], x was practically zero. Monomer order was 1.1 in benzene and pyridine but much less than unity (0.65–0.70) in carbon tetrachloride and chloroform. Kinetic analysis indicated that the initiation process was monomer and solvent dependent. The halomethane solvents enhanced the polymerization rate through their active participation in the initiation or radical-generation steps. End-group analysis indicated incorporation of basic (amino) end-groups in the polymers. The kinetic non-ideality was explained on the basis of significant initiator-dependent termination through primary radicals or via degradative transfer to initiator.