Synthesis of poly(N,N-dimethylacrylamide) via nitroxide-mediated radical polymerization

Poly(N,N-dimethylacrylamide) (PDMA) with a low polydispersity was prepared via stable free radical polymerization (SFRP) using 2,2,6,6-tetramethyl-1-piperdinyloxy nitroxide(TEMPO). PDMA with a polydispersity of 1.55 (M-n = 10 600) was obtained for [TEMPO]/[AIBN] = 1.0 with quantitative monomer conversion; higher [TEMPO]/[AIBN] ratios decreased conversion. The polydispersity of PDMA was higher and polymerization times were shorter compared to SFRP of styrene or n-butyl acrylate. Attempts to prepare higher molecular weight PDMA with low polydispersity were unsuccessful. When polystyrene-TEMPO was used as a macroinitiator, N,N-dimethylacrylamide could be polymerized, but the conversion was low. Unlike styrene or acrylate polymerization, SFRP of N,N-dimethylacrylamide is not a living process, as evidenced by an unsuccessful incremental-monomer-addition experiment.