Permanently Mechanically Adjustable Photothermal Catalytic Spontaneous Double Cross‐Linking Network Enables Durable and Stretchable Plant Skin‐Like Materials

Abstract In cellulose‐based plastics, as a type of thermoplastic and thermosetting materials, the excellent balance of mechanical strength and ductility poses a large challenge. To tackle this problem, a novel approach is devised to introduce reversible non‐covalent ester cross‐linking into dynamic covalent hydrogen‐bonded polymer networks. However, the formation of ester bonds typically requires excess reactants and dehydrating agents, which is energy‐intensive, environmentally harmful, and costly. To address these concerns, inspired by polyester‐rich plant bark, a supramolecular composite material is developed. It can be dissolved and regenerated using a binary solvent system (choline hexanoate/choline chloride‐oxalic acid). In water, this supramolecular composite material underwent self‐healing and ester exchange reactions to form double‐cross‐linked networks, interfaced with photo‐thermal catalysis promoting the reaction due to its high photo‐thermal conversion efficiency (86.7%) and water evaporation rate (1.38 kg m −2 h −1 ). This enables the rapid and repeatable construction of durable and stretchable biomaterials. The mechanical properties of the supramolecular plastic can be adjusted by solar photo‐thermal conditions of the synthesis environment. These materials exhibit high performance in solar water evaporation and have self‐healing properties and are degradable, recyclable, and capable of eliminating their own adhesions.