Cushion-and-Preserve: A Biodegradable Copolyester/Montmorillonite Elastomer with Programmed ClO2 Delivery for Extended Shelf Life

Postharvest losses of fresh produce are driven by mechanical damage and microbial decay, yet existing preservation technologies typically address only one of these challenges. To bridge this gap, a biodegradable, ultraviolet (UV)-crosslinked copolyester that integrates impact cushioning with controlled chlorine dioxide (ClO 2 ) release via sodium-chlorite-loaded montmorillonite (NaClO 2 @MMT) is engineered. The novelty of this work lies in the synergistic combination of a cushioning elastomeric matrix with a functionalized nanofiller, enabling a single-material strategy for simultaneous mechanical protection and controlled ClO 2 delivery associated with delayed visible spoilage. The optimized matrix (PISBEN19, 10 mol% itaconic acid) combines high elasticity (elongation 208.01%, toughness 708.77 kJ m -3 ). The incorporation of 15 parts NaClO 2 @MMT (PISBEN19-15) significantly enhanced the tensile strength to 3.97 MPa, representing an increase of approximately 459%, while enabling sustained ClO 2 release over approximately 15 days under high-humidity conditions. In cherry-tomato trials at 25°C, PISBEN19-15 suppresses respiration and ethylene, limits weight loss (0.76% at day 15; 74.4% reduction vs. control), preserves firmness and total soluble solids, and extends shelf life by ≥6 d without decay. The mechanistic tests suggest that NaClO2@MMT contributes to both mechanical reinforcement and sustained release, while a preliminary drop test provides initial evidence of impact attenuation. This dual-function eco-friendly elastomer offers a single-material strategy to simultaneously address impact and infection, with significant potential for reducing postharvest losses, particularly in regions lacking advanced cold-chain infrastructure.