Degradation of several polyamides in soils

Abstract

Synthetic polyamides (nylons) are generally hard to be decomposed under natural environmental conditions either through biological or hydrolytic processes.'-4 Their high resistance to degradation is caused mainly by the high symmetry of their molecular structures and strong interchain hydrogen bondings, which result in a highly ordered crystalline morphology. Therefore, several procedures for the weakening of these characteristics, such as the introduction of substituents in their repeating units, chemical modification, and even physical processing, are effective for the increase of their biodegradability.'-6 However, the degradation of nylons having relatively simple repeating units has been scarcely reported up to date.7 The present note is concerned with the degradability of three kinds of polyamides (4,5, and 6 ) prepared from 2pyrrolidone, t-caprolactam, and a bicyclic lactam, 8-oxa-6-azabicyclo[ 3.2.lloctan-7-one ( 1, 2, and 3, respectively), in several kinds of soils and in a phosphate buffer (see Scheme 1 ). The bicyclic oxalactam 3 (abbreviated BOL) has both five-and seven-membered lactam rings and its quasi-living anionic polymerization in dimethyl sulfoxide gives a monodisperse and well-defined novel polyamide having a tetrahydropyran ring in the repeating