Biodegradable Multiblock Copolyesters Prepared from ε-Caprolactone, l-Lactide, and Trimethylene Carbonate by Means of Bismuth Hexanoate

Abstract

Telechelic random copolymers were prepared by copolymerization of e-caprolactone (eCL) and trimethylene carbonate (TMC) in bulk using bismuth(III) hexanoate, Bi(OHex)3, as initiator. These copolymers were characterized by 1H and 13C NMR spectroscopy. A−B−A triblock copolymers were synthesized by chain extension of these random copolymers with l-lactide, whereby the chain length of the amorphous central blocks and of the crystalline poly(l-lactide) blocks were varied. Finally, the triblock copolymers were transformed into multiblock copolymers by chain extension with 1,6-hexamethylenediisocyanate. All three synthetic steps were performed in a “one-pot-procedure”. The resulting multiblock copolymers were characterized by 1H NMR spectroscopy, SEC measurements, DSC measurements, and stress−strain measurements. Typical mechanical properties of thermoplastic elastomers were detected.