DEGRADATION BEHAVIOR OF BLOCK-COPOLYMERS CONTAINING POLY(LACTIC-GLYCOLIC ACID) AND POLY(ETHYLENE GLYCOL) SEGMENTS

The degradation behaviour of a new class of multi-block copolymers con taining poly(D,L-lactic-glycolic acid) (PLGA) and poly(ethylene glycol ) (PEG) segments was studied under conditions mimicking those found in biological fluids. The dissolution times of the new PLGA-PEG multi-bl ock copolymers mainly depend on the length of the PEG segments present in their structure, i.e., on their PEG content on a weight/weight bas is. At higher PEG contents, partially degraded PLGA segments are broug ht in solution by attached PEG segments. In all cases, the dissolution rates decrease by increasing the total surface area of the specimens tested. (C) 1996 Elsevier Science Limited