Poly(butylene adipate-co-terephthalate) with synergistically enhanced mechanical, moisture/oxygen barrier, and degradation performance via embedding immobilized enzyme

Abstract

Poly(butylene adipate-co-terephthalate) (PBAT) has gained significant attention as a promising biodegradable polymer and a potential alternative to traditional polyethylene. However, achieving a balance among mechanical performance, moisture/oxygen barrier properties, and efficient degradability remains challenging. The mechanical and barrier properties of PBAT can be enhanced by improving butylene terephthalate (BT) unit content and increasing the BT segment crystallization. However, this enhancement is inevitably accompanied by reduced degradability and leads to its failure to meet the international testing standards for biodegradable materials. In this study, metal–organic framework (MOF)-immobilized enzymes were incorporated into PBAT with high BT content, where the immobilized enzymes were used to maintain its degradability, while the high BT content in PBAT was employed to enhance its mechanical properties and moisture/oxygen barrier performance. An optimized loading of immobilized enzymes maintained the mechanical integrity and barrier performance of PBAT, yielding more than a twofold increase in Young's modulus and nearly double the barrier performance compared with those of conventional PBAT. Furthermore, the PBAT with immobilized enzymes exhibited a significant improvement in the biodegradation rate, attributed to the improved thermal stability and water uptake of the MOF immobilized enzymes, as well as the reinforced polymer–enzyme interfaces. As a result, the incorporation of 2 wt% immobilized enzyme accelerated its hydrolysis rate by 9–38 times compared with that of neat PBAT and 3–6 times compared with that of the free enzyme. The optimized material effectively resolves the intrinsic contradiction between sustainability and service performance of conventional PBAT. This work offers a potential strategy for designing high-performance sustainable polymeric materials.