In Situ Esterification and Hydrogen Bonding Synergy: Ternary Deep Eutectic Solvent for Reinforced PBAT /Starch Composites

Abstract

This study prepared high‐performance PBAT/starch composite films using biodegradable PBAT, starch, and a ternary deep eutectic solvent (DES) composed of glycerol/choline chloride/citric acid. The films were fabricated via in situ plasticization of starch with DES, melt blending, and film blowing. With 1.13 parts citric acid, 10.13 parts total DES, and 20% starch, the composite film achieved a longitudinal tensile strength of 19.63 MPa and elongation of 449%, and a transverse tensile strength of 20.75 MPa and elongation of 500%. Compared to the traditional glycerol‐plasticized system (8.43/8.77 MPa), strength increased by over 130%; compared to the binary DES system (15.07/15.45 MPa), strength further increased by over 30%. The composite film also showed good thermal stability within the processing range (150°C–160°C), and the water contact angle was significantly improved, demonstrating high strength, toughness, enhanced hydrophobicity, and good thermal stability. The ternary DES effectively disrupts the crystalline structure of starch for efficient plasticization, and the citric acid it contains may trigger interfacial esterification crosslinking between starch and PBAT, thereby enhancing two‐phase compatibility and stress transfer efficiency. This developed film has application potential in biodegradable packaging, disposable products, and environmentally friendly daily‐use films.