POLYMERIZATION OF GLYCOLIDE PROMOTED BY OMEGA-AL-ALKOXIDE POLY(EPSILON-CAPROLACTONE) MACROINITIATORS AND FORMATION OF STABLE COLLOIDAL DISPERSIONS

Block polymerization of glycolide (GA) and epsilon-caprolactone (epsil on-CL) has been initiated with aluminum alkoxides, such as Al(O(i)Pr)3 and Et2AlOCH2X (where X = -CH2-Br and -CH2O-C(O)-C(Me)=CH2), in THF a t 40-degrees-C. Structure and composition of block copolyesters have b een characterized with respect to the molecular weight by NMR spectros copy and thermal analysis. Copolymerization is typically living, so th at block copolyesters have been synthesized with predictable molecular weight and composition. The inherent insolubility of polyglycolide bl ock is responsible for the heterogeneity of the polymerization medium and formation of stable, non-aqueous colloidal dispersions. This effec t is especially pronounced at high GA/epsilon-CL molar ratios. Colloid al dispersions have been analyzed by transmission electron microscopy (TEM) and photocorrelation spectroscopy (PCS).