Synthesis, characterization and hydrolytic degradation of polyester-urethanes obtained by lipase biocatalysis

Abstract

The enzymatic synthesis of ¿¿¿-telechelic polycaprolactone diols (HOPCLOH) and block copolymers was studied. Synthesis of ¿¿¿-telechelic PCL diols was carried out by enzymatic ring opening polymerization with Yarrowia lipolytica lipase immobilized on Lewatit VP OC K2629 and Amberlyst 15, and using ethylene glycol, diethylene glycol and polyethylene glycol as initiators. Biodegradable linear polyester-urethanes were prepared from synthesized PCL diols and hexamethylenediisocyanate (HDI). Polyester-urethanes degradation was studied using thermogravimetric analysis (TGA) and hydrolysis (alkaline, acidic and neutral). It was found that content of ether linkages influences the thermal stability and hydrolytic degradation behavior of the analyzed polyurethanes. Hydrolytic degradation proceeds faster in alkaline media, in agreement with the expected susceptibility of ester COO¿ bonds to degradation in the polyester urethanes.