1978 Volume 35 Issue 12 Pages 795-801
The absolute values of propagation rate constant (kp) and termination rate constant (kt) of N, N-dimethylacrylamide were determined by means of a rotating sector method in bulk at 30°C. The overall rate of polymerization initiated with α, α′-azobisisobutyronitrile was found to be proportional to square root of the initiator concentration and to the monomer concentration, indicating that the polymerization proceeded by a chain mechanism involving the termination by the coupling or disproportionation of growing radical. The absolute values of kp and kt determined at 30°C were 27200 and 3.54×109 l mol-1, s-1, respectively. Reactivities of N, N-dimethylacrylamide and poly (N, N-dimethylacrylamide) radical were discussed on the basis of the rate constants of cross-propagation reactions in the copolymerization with other monomers. Although N, N-dimethylacrylamide was as reactive as common conjugated monomers, the polymer radical was found to be much more reactive than common conjugated polymer radicals such as polystyrene or poly (methyl acrylate) radical. The unexpected high reactivity of the polymer radical seems to be accounted for by the decrease in the interaction of the unpaired electron of the radical with the carbonyl π electrons due to the independent interaction of the lone pair electrons on the nitrogen with π electrons of the carbonyl group.
