Cyclopolymerization. VI. Polymerization mechanism of N‐methyl‐N‐allylmethacrylamide at lower temperature

Abstract

AbstractMechanistic investigations on the polymerization of N‐methyl‐N‐allylmethacrylamide (MAMA) at lower temperature were carried out based upon the ESR studies of MAMA and its monofunctional counterparts irradiated with 60Co γ rays. Cyclopolymerizability of MAMA was also studied in connection with the hindered rotation about its amide CN bond. The propagating radical observed is only related to the methacryl group but not to the allyl group both in MAMA and its monofunctional counterparts. Polymerization at −78°C yielded a polymer with a lower degree of cyclization(88.8%) as compared with that of polymers formed at higher temperatures (93.5% above 0°C). A structural study revealed that the increment of the unsaturation in the poly‐MAMA obtained at −78°C is due to the allyl group and the content of pendant methacryl group is almost unchanged over the temperature range from −78 to 120°C. These results led to the conclusion that the polymerization of MAMA at −78°C proceeds mainly through the methacryl group, the rate‐determining step is the cyclization reaction, and, in addition, cyclization reaction scarcely occurs when it polymerizes through the allyl group. Since MAMA is frozen into a glassy state, the effect of glass transition temperature (Tg) has been studied and it was suggested that the polymerization of MAMA proceeds only above Tg.