In-situ construct dynamic bonds between lignin and PBAT by epoxidized soybean oil to improve interfacial compatibility: processing, characterization, and antibacterial activity for food packaging

Abstract Poly(butylene adipate-co-terephthalate) (PBAT) is a synthetic biodegradable thermoplastic copolyester. In this study, we aimed to enhance lignin’s compatibility with PBAT for polymerization. Epoxidized soybean oil (ESO) was introduced as an interfacial modifier to improve lignin-PBAT interactions. A lignin/ESO/PBAT composite film was fabricated via a solvent-free one-pot method using torque rheometry. ESO formed dynamic covalent bonds between lignin and PBAT, promoting lignin dispersion. When 5 wt% ESO was added to PBAT/lignin composites (1 % lignin), tensile strength increased to 24.57 MPa (from 24.37 MPa) and strain to 956.12 % (from 922.41 %). Antibacterial assays and food freshness tests confirmed the composite’s suitability for food packaging. This work provides an eco-friendly strategy for high-performance lignin/PBAT films.