Isosorbide as a building block for Poly(butylene adipate-co-terephthalate)-based copolyesters with enhanced mechanical properties and tunable biodegradability

Developing bio-based copolyesters with excellent mechanical properties, controlled degradation, and easy industrial production would significantly promote adopting disposable green products and advancing a circular economy. A series of poly(butylene adipate/terephthalate-isosorbide) (PBIAT) were successfully synthesized by introducing varying amounts of biologically derived isosorbide (IS) as the modifying monomer into cost-effective poly(butylene adipate-co-terephthalate) (PBAT). It was demonstrated that IS effectively enhances the rigidity of molecular chains, thereby the glass transition temperature of PBIAT increased almost linearly with IS content, while the tensile strength, elongation at break, and tensile toughness improved by up to 85 %, 69 %, and 42 %, respectively, compared to neat PBAT. Moreover, studies on the degradability of the copolyester demonstrated that PBIAT exhibits controlled degradation capability. The stability of PBIAT in a neutral solution is consistent with that of PBAT, whereas the degradation rate of PBIAT increased by up to 70 % in the enzyme solution. This work provides insights into the design of isosorbide-modified degradable polyesters for regulating the mechanical properties and degradation rate.