Synthesis and Properties of Stereoblock Copolymers Composed of Lactide and ε-Caprolactone

Abstract

Sequential copolymerization of l-lactide (LLA) with ε-caprolactone (CL) followed by that of d-lactide (DLA) with CL was carried out to synthesize Poly(LLA-r-CL)-b-Poly(DLA-r-CL). The obtained Poly(LLA-r-CL)-b-Poly(DLA-r-CL) showed only one T_m ca. 30°C higher than that of Poly(LLA-r-CL), indicating selective formation of stereocomplex crystals. The stereoblock Poly(LLA-r-CL)-b-Poly(DLA-r-CL) exhibited high elongation at break similarly to homochiral Poly(LLA-r-CL). Their biodegradation test using proteinase K showed lower degradability than that of homochiral Poly(LLA-r-CL).