Polymerization of β-Propiolactone Initiated by Sodium Chloroaurate

Bulk polymerization of β-propiolactone (β-PL) initiated by sodium chloroautae (NaAuCl₄·2H₂O) at 30°C. was investigated. The polymerization initiated by NaAuCl₄·2H₂O is accelerated by photoirradiation similar to the polymerization of N-vinylcarbazole as mentioned in a previous paper. The time-conversion curve of the polymerization under photoirradiation reaches a dead end, particularly when the polymerization is carried out in a quartz vessel. The intial rate of polymerization is proportional to [Auᴵᴵᴵ]～1 in the light and [Auᴵᴵᴵ]～2 in the dark. From the effects of additives and solvents, and electronic spectroscopies, it is concluded that the polymerization is cationic initiated by charge transfer process from β-PL to the Auᴵᴵᴵ and/or the Auᴵᴵ species on other decomposition products of Auᴵᴵᴵ