Synthesis and enzymatic biodegradation of co-polyesters consisting of divanillic acid with free hydroxyl groups

Abstract

We report the synthesis of poly (hexamethylene adipate-co-divanillate) (PHADV) from divanillic acid (DVA), adipic acid, and 1,6-hexanediol. The polymerization of silyl-protected DVA monomers and subsequent deprotection produced PHADV with free hydroxyl groups for the development of new biodegradable plastics. The weight-average molecular weights of the PHADVs were 2.3–4.9 × 104. The amorphous PHADVs had glass transition temperatures (Tgs) in the range -48–111 °C, which increased as the number of DVA units increased. It was possible to thermo-press PHADV25 and PHADV50, which comprised 25% and 50% DVA, respectively, into flexible films. PHADV50 exhibited a tensile strength of 16.8 MPa and an elongation at break of 300%. PHADV25 was successfully degraded by Humicola insolens cutinase (HiC), and the weight loss reached 50% after 10 days. DVA-based polyesters with phenolic hydroxy groups are promising bio-based and biodegradable aromatic polymers with favorable thermal and mechanical properties.