Anionic polymerization of a series of N, N-dialkylmethacrylamides Such as N-methacryloylazetidine (M4), N-methacryloylpyrrolidine (M5), and N-methacryloylpiperidine (M6) was carried out with diphenylmethyllithium (Ph2CHLi) or diphenylmethylpotassium (Ph2CHK) in the presence of LiCl or Et2Zn in THF to clarify the relationship between polymerizability and monomer structure. Poly(M4)s possessing predicted Molecular weights and very narrow molecular weight distributions (M-w/M-n < 1.1) were obtained quantitatively with Ph2CHLi/LiCl or Ph2CHK/Et2Zn at -40 to 0 degrees C within 24 h. From the polymerizations of M4 at the various temperatures ranging from -40 to -20 degrees C, the apparent rate constant and the activation energy of the anionic polymerization were determined as follows: In k(p)(ap) = -6.17 x 10(3)/T + 22.4 L mol(-1) s(-1) and 51 +/- 5 kJ mol(-1), respectively. Compared to the previous report oil the anionic polymerization of N-methacryloyl-2-methylaziridine (M3), the polymerization rate of M4 was significantly slower and the activation energy was slightly larger, indicating the lower polymerizability of M4. The acryloyl counterpart, N-acryloylazetidine (A4), also underwent the anionic polymerization to afford the well-defined polymer quantitatively. The polymerizations of M5 gave the polymers in 30-77% yields but did not complete even after I week at 0 degrees C. By contrast, no polymer was obtained from the anionic polymerization system of M6 similar to the case of N,N-dimethylmethacrylamide (DMMA). From the experimental results, it was demonstrated that the polymerizability of a series of N,N-dialkylmethacrylamides with cyclic substituents decreased drastically with increasing the ring size from three to six (M3 > M4 > M5 >> M6 = DMMA). The observed relative 3 polymerizability was well correlated with the chemical shifts of vinyl beta-carbons for monomers in the C-13 NMR spectra. The NMR data Suggested that the polymerizable M3 and M4 attained effective conjugation between C=C and C=O double bonds, while M5, M6, and DMMA had negligible conjugation effects.