Influence of initiator in controlled radical polymerization using nitroxide capping: the case of N,N-dimethylacrylamide.: Synthesis of block copolymers of 4-vinylpyridine and N,N-dimethylacrylamide

The behaviour of N,N-dimethylacrylamide (DMAA), when involved in a nitroxide-mediated radical polymerization, depends on the initiator. 2,2′-azobis (isobutyronitrile) triggers a fast reaction which cannot be proved to be controlled. On the contrary, when benzoyl peroxide is used, the reaction proceeds slowly and chain-growth control can be evidenced by studying the evolution of both conversion vs. time and number average molar weight vs. conversion. In the present case, poly(N,N-dimethylacrylamide)s were synthesized, whose polydispersities revealed to be much lower than the indices ever reached so far with 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO). Copolymers of DMAA were then obtained using TEMPO-terminated poly(4-vinylpyridine) as a macroinitiator.