BLOCK-COPOLYMERS OF L-LACTIDE AND POLY(ETHYLENE GLYCOL) FOR BIOMEDICAL APPLICATIONS

Poly (L-lactide)-poly (oxyethylene)-poly (L-lactide) block copolymers obtained in bulk, by a ring opening mechanism, from poly(ethylene glyc ol)s (PEG)s and L-lactide (LA), at 120-140 degrees C, in the absence o f added catalysts are described. By using PEGs with different molecula r masses, 3000 and 35 000, respectively, and varying the initial molar ratio LA to PEG, two series of copolymers with different molecular ma sses, relative length of blocks and hydrophilicity were obtained. Phys ico-chemical characterization of the copolymers had been previously pe rformed. The morphological characteristics of the copolymers were inve stigated by means of X-ray diffractometry, optical and scanning electr on microscopy. The biological properties of the materials were determi ned by evaluating their cytotoxicity, cytocompatibility, hemocompatibi lity and degradability using different standard tests. The results obt ained indicate that the block copolymers synthesized may be useful for biomedical applications, in particular as resorbable drug vehicles. T he materials are brittle and their mechanical properties are not appro priate for implant devices.