Investigations on the role of acyl initiators and CO2 in nylon 4 polymerization

Summary The preparation of high molecular weight nylon 4 with alkali metal pyrrolidonate catalysts, acyl initiators, and CO₂ was studied. Isolated sodium pyrrolidonate and the appropriate amount of acyl initiator gave unusually high molecular weight nylon 4 (m_w >200,000). The molecular weight-initiator concentration relationship indicates that acyl compounds play a dual role in the polymerization, acting both as initiators and scavengers for chain-terminating impurities. One potential chain terminator was identified as 4-aminobutyric acid. The high polymer molecular weights obtained in the presence of CO₂ can also be explained by the scavenging of chain terminators by CO₂. Determination of the number of growing chains, however, shows that CO₂, unlike the acyl compounds, is not an initiator in nylon 4 polymerization.Presented at the 1984 International Congress of Pacific Basin Societies, Honolulu, Hawaii, December 1984