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Alkaline polymerization of caprolactam. XXIX. Mechanism of chain growth in anionic lactam polymerization

1968; Wiley; Volume: 23; Issue: 1 Linguagem: Inglês

10.1002/polc.5070230121

1935-3065

J. Šebenda,

biodegradable polymer synthesis and properties

Abstract When butyrylenantholactam is used as acyllactam and sodium caprolactam as the source of lactam anions, the position of the lactam anion incorporated in the first chain‐growth step may be determined. To avoid the interference of transacylation leading to butyrylcaprolactam and sodium enantholactam the reaction was stopped at very low extents. Determination of the structure of the reaction products revealed that the incorporated caprolactam anion is present as the end‐standing acylated lactam unit and the enantholactam unit is inside the chain. This position of monomer units proves that the chain‐growth reaction consists of acylation of lactam anions by the cyclic carbonyl group of an acylated lactam and not by insertion into imide or β‐ketoamide groups. At 50°C. the rate of transacylation was found to proceed 5 times faster than the chain growth; the rate of condensation reactions of imide groups amounts to 20% of the rate of the chain‐growth reaction.