The absence of CO2 in nylon-4 prepared with KOH + radioactive CO2 catalyst

This report describes the polymerization of 2-pyrrolidone with KOH + radioactive CO2 catalyst and the radioactive assay of the polymer, aimed to detect CO2 incorporation in nylon-4. Some possible mechanisms for the role of CO2 in producing nylon-4 are suggested. Comparative evaluations are made with the mechanisms of CO2 incorporation in nylon-7 presented in other reports. The results show that water washing removes most of the radioactivity from the polymer. The molecular weight of the polymer is 228,000; it was found that the polymer contained only about 1 CO2/100 polymer molecule. Thus, it can be concluded that CO2 is not incorporated to any significant degree into nylon-4, and the small radioactivity is probably caused by traces of residual CO2 catalyst. The absence of CO2 in anionic nylon-4 is in sharp contrast with the reported high CO2 content in anionic nylon-7