Innovative crosslinking and foaming Strategies for Advancing biodegradable composite foams: Enhancing Foamability, Flexibility, and thermal insulation

• Ultralight and biodegradable composite foams were successfully fabricated. • Composite foams achieved by physical foaming showed a fine cellular structure. • PLA and ADR were introduced to achieve anti-shrinkage of foams. • The foams exhibited incomparable resilience and thermal insulation. Ensuring thermal insulation stability under an extreme condition and optimizing energy utilization efficiency emerge as a pivotal concern. Bio-based poly(butylene adipate-co-terephthalate) (PBAT) foams, characterized by irreplaceable flexibility, biodegradability, and thermal insulation, are employed as a candidate for building insulation. However, the inadequate foamability and inescapable contraction issue of PBAT foam constrains its advancement in the domain of flexible thermal insulation. In this study, an innovative strategy was proposed wherein chain crosslinker ADR and corn-derived polylactic acid (PLA) are embedded within PBAT matrix, augmented by the physical foaming process, designed to alleviate the shrinkage and improve the thermal insulation of foams. It can be found that the addition of reactive functional groups enhances interfacial interactions of PBAT/PLA system, leading to a more cohesive and dispersed interface between the two phases. Moreover, the synergistic enhancement of physical foaming facilitates the attainment of the PBAT/PLA/ADR foam with a stable expansion ratio and ultra-low thermal conductivity, which can reach 17.4 and 37.5 mW/(m·K), respectively, 93 % and 14 % higher than those of PBAT foam. As a proof of concept, this study offers a novel environmentally-friendly strategy to develop recyclable, highly flexible, and thermally insulating biodegradable foam.