Designing ultratough, malleable and foldable biocomposites for robust green electronic devices

Abstract

Polymers from renewable resources play a key role in the paradigm shift towards a sustainable society. However, two common bioplastics, polylactic acid (PLA) and polyhydroxybutyrate (PHB) still lack the toughness and flexibility for practical applications. This work reports a design strategy to fabricate robust biocomposites based on PLA and PHB by direct mixing with a small amount of biodegradable poly(ethylene oxide) (PEO). The PLA/PHB/PEO green composites exhibit an extreme elongation of ∼300% (50-fold increase) and a tensile fracture energy up to ∼87 MJ m⁻³ (90-fold increase), while maintaining high strength (∼49 MPa) and modulus (∼3.4 GPa) comparable to commercial poly(ethylene terephthalate). Even after repeated bending, folding and crumpling, the biocomposite film remains highly stretchable (elongation ∼ 100%). The excellent mechanical performance is attributed to interfacial miscibility and entanglement networks driven by favorable mixing entropy. The reported composite is the first PLA/PHB based bioplastic that can be shaped, folded and crumpled, demonstrating its prospects as a substrate in green flexible electronic devices. This design strategy opens ample opportunities for facile preparation of biopolymer materials for future applications.