Superfoldable Bamboo by Microwrinkling Engineering for 3D Origami Structures

Origami-inspired materials enable sophisticated three-dimensional (3D) structural designs, yet conventional materials face an intrinsic conflict between strength and flexibility. Herein, foldable bamboo (FB) is fabricated by mimicking the rove beetle wing's microstructure and bidirectional folding mechanism, coupled with a microwrinkling engineering and waterborne polyurethane (WPU) loading strategy to decouple mechanical trade-offs. Selective lignin removal and cellulose framework softening induce rearrangement of the hydrogen bond network, driving microfibril aggregation and formation of surface microwrinkles. These features enhance interfacial friction and mechanical interlocking. Reinforced by WPU penetration and film formation, this multiscale structure (from molecular to macro levels) endows FB with exceptional folding endurance (24,793 cycles, >24× higher than bamboo veneer, BV). Simultaneously, FB achieves a 59.18% increase in transverse tensile strength, 16.06% higher elongation at break, and 54.48% improved bursting strength. These properties, especially folding endurance, not only surpass most biobased materials but also compete favorably with many polymers and metals. Notably, FB further demonstrates enhanced hydrophobicity, tunable light transmittance, inkjet compatibility, and unlimited splicing capability, enabling robust performance under tension, compression, and folding. These advantages underpin FB's large-scale applications in sustainable, sophisticated 3D structural designs, such as packaging, decoration, and outdoor engineering.