Polymerization of N‐methyl‐β‐propiolactam with ionic catalysts

The polymerization of N‐methyl‐β‐propiolactam with various ionic catalysts in bulk was carried out at 140–190°C. Organic compounds containing a carboxyl group have a high catalytic activity for the polymerization and gave crystalline polymer melting at 180–225°C. No polymer of N‐methyl‐β‐propiolactam was formed at 140°C., but the polymerization of N‐methylacrylamide took place. The polymer of N‐methylacrylamide was amorphous and its infrared spectrum was quite different from that of poly‐N‐methyl‐β‐propiolactam. The infrared spectrum of poly‐N‐methyl‐β‐propiolactam showed a major absorption peak characteristic of a polyamide structure. On the basis of the infrared spectrum of an equimolar mixture of monomer and catalyst heated at 130°C., a mechanism was proposed.