No abstract

SYNOPSISTwo types of novel biodegradable epoxy resins, carrying cycloaliphatic-epoxy and glycidyl ester end-groups, have been synthesized from hydroxy-telechelic oligoesters. The cycloaliphatic-epoxy end-groups were based on either methyl cis-4-cyclohexene-2-(carboxylic acid) -1-carboxylate or 3-cyclohexene-1-carboxylic acid. These compounds were reacted with hydroxy-telechelic poly ( E-caprolactone-co-D,L-lactide ) oligoesters, yielding cycloaliphatic-olefin-terminated oligomers. Conversion of the olefin to the epoxide groups was achieved using a phase transfer epoxidation with a n inorganic peracid derived from the reaction of phosphoric acid, sodium tungstate, and hydrogen peroxide. Aliquat 336, a quaternary ammonium salt, acted as the phase transfer catalyst. Nearly theoretical conversion of hydroxy to epoxy end-groups was achieved in only one case, however, alternative variations of this method of synthesis show promise. T o prepare glycidyl ester-terminated prepolymers, hydroxy-telechelic poly ( E-caprolactone) oligoesters were reacted with succinic anhydride, in 1,2-dichloroethane with 1-methylimidazole as catalyst, resulting in (carboxylic acid) -terminated oligomers. After conversion of the end-groups to the potassium carboxylate salt by titration with methanolic KOH, the isolated salt was dried and reacted with epibromohydrin in acetonitrile at reflux, using a n 18-c-6 crown ether as the phase transfer catalyst, thus preparing the (glycidyl ester) -telechelic prepolymer. Epoxide equivalent weights differed by 2.7-7.1% from the theoretical values. These cycloaliphatic-epoxide and glycidyl ester-terminated prepolymers may be crosslinked with anhydrides or amines, respectively, to produce totally bioabsorbable networks. 0 1993 John Wiley & Sons, Inc.