POLY(ESTER-ETHER-ESTER) BLOCK-COPOLYMERS AS BIOMATERIALS

Poly(ester-ether-ester) block copolymers, belonging to a class of biod egradable materials, were synthesized from poly(ethylene glycol) and e psilon-caprolactone by a simple ring-opening mechanism, which avoids t he use of potentially toxic inorganic or organometallic initiators. Th e morphological and mechanical properties of such materials were inves tigated by gel-permeation chromatography, vapour pressure osmometry, p roton magnetic resonance, infrared spectroscopy, differential scanning calorimetry, X-ray diffractometry and stress-strain tensile tests. Th e biocompatibility was investigated by cytotoxicity and hemocompatibil ity tests; the cytotoxicity was tested by the Neutral Red uptake assay , the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide as say, the Kenacid Blue R-binding method, and by the cell proliferation test on polymer films; the hemocompatibility was tested by the contact activation both of the coagulation cascade (intrinsic pathway), by th e plasma prekallikrein activation test, and of the thrombocytes, by me asuring the release of platelet factor 4 and beta-thromboglobulin. The experimental results show that such a polymerization process permits high-molecular mass block copolymers with relatively good tensile and mechanical properties to be obtained. Their cyto- and hemo-compatibili ty makes them suitable for employment as biomaterials.