Remarkable elasticity and enzymatic degradation of bio-based poly(butylene adipate-co-furanoate): replacing terephthalate†
Biodegradable polyesters, such as poly(butylene adipate-co-terephthalate) (PBAT), can trigger the hydrolysis of esters in a natural environment. However, biodegradability does not guarantee its eco-friendliness due to the concerns associated with terephthalic acid. Substitution by biomass-based counterparts no longer ensures “truly” eco-friendly biodegradable polyesters. In this study, we have used poly(butylene adipate-co-furanoate) (PBAF), which utilizes a biomass-derived substituent, furan-2,5-dicarboxylic acid (FDCA), and have proven that this is superior from the perspective of both mechanical performance and enzymatic degradation. Compared to its terephthalate counterpart, PBAF exhibits remarkable elasticity upon stretching: when released beyond 800% extension, PBAT almost malfunctioned, whereas PBAF exhibited instant elastic recovery. This results in PBAT and PBAF having a similar tensile strength in the range of 50–70 MPa at the ring fraction of 50 to 80 mol%. During the enzymatic degradation using lipase from Thermomyces lanuginosus, PBAF with a ring fraction of 50 mol% solely undergoes hydrolysis due to enzyme specificity. Ex situ spectroscopic analysis confirms that the participation of FDCA ester groups in the early stages of degradation triggered the successive hydrolytic reaction. Thus, understanding the structural characteristics of FDCA would open new opportunities in the field of sustainable plastic industries.