ACCELERATED DEGRADATION OF POLY(EPSILON-CAPROLACTONE) BY ORGANIC AMINES

The solid-state degradation of poly(epsilon-caprolactone) catalyzed by primary, secondary and tertiary alkylamines was investigated. The deg radation process was monitored by weight loss and molecular weight cha nge measured by gel permeation chromatography. Degradation studies wer e conducted at 37 degrees C in methanol solutions of the alkylamines. Primary alkylamines caused rapid weight loss (i.e., similar to 90% wei ght loss in 30 days) that depended on alkylamine concentration, molar ratio of alkylamine to poly(epsilon-caprolactone) monomer and alkyl ch ain length. The secondary alkylamines caused less rapid polymer weight loss (i.e., similar to 90%) weight loss within 80 days). One tertiary alkylamine (N,N-diisopropylethylamine) showed little catalytic effect while a bicyclic tertiary alkylamine (quinuclidine) was about as cata lytic as the primary alkylamines. The degradation products isolated wh en primary alkylamines were used include both esters and amides indica ting that nucleophilic attack by the alkylamines competed with the ami ne-catalyzed methanolysis reaction. Only ester moieties could be ident ified in the products from reactions containing secondary and tertiary alkylamines, which indicated that they acted as nucleophilic catalyst s. All of the primary alkylamines reduced poly(epsilon-caprolactone) m olecular weight from about 25,000 to 10,000 within 10 days after which the molecular weight of the remaining solid leveled off even though w eight loss continued.