Enzymatic synthesis and properties of novel biodegradable and biobased thermoplastic elastomers

Novel biodegradable and biobased thermoplastic elastomers, poly[dodecanolide-12-hydroxystearate (12HS)], poly(pentadecanolide-12HS) and poly(hexadecanolide-12HS) with M_ws of 140,000-290,000 g mol⁻¹ were prepared by the enzymatic copolymerization of a macrolide as the hard segment and methyl 12HS as the soft segment. Their thermal properties, such as T_m and T_c, were measured by DSC. Physicochemical and mechanical properties, such as crystallinity, were also measured. The polymer structures were analyzed with respect to the sequence of the two monomers by ¹H NMR spectroscopy using an europium shift reagent. The randomness of the two monomer units in the polymer chain increased with the polymerization time. Both Young’s modulus and tensile strength decreased with increasing 12HS content in the copolymer. In contrast, elongation at break increased with increasing 12HS content, thus demonstrating the copolymers’ elastomeric properties. These copolymers showed biodegradabilities by activated sludge, which also increased with increasing 12HS content.