State‐Dependent Noncovalent Cohesion Enables Durable and Recoverable All‐Biomass Photothermal Coatings

ABSTRACT Balancing service durability with practical material recovery remains challenging for functional coatings because permanent network fixation can hinder reuse. An all‐biomass photothermal coating with state‐dependent noncovalent cohesion is reported, fabricated by organizing lignocellulosic nanofibers (LCNF), biochar (BC), and carnauba wax through a bioinspired “jet‐to‐net” spray process. Lignin‐retaining LCNF forms an entangled capture scaffold with hydroxyl and aromatic interaction sites, while BC supplies photothermal absorption and roughness and carnauba wax establishes a low‐polarity interface. Pareto analysis identifies a composition that balances water repellency, mechanical retention, and photothermal response. Molecular calculations further reveal distributed hydrogen‐bonding, aromatic, and wax‐mediated dispersion interactions that strengthen collectively after solvent evaporation but weaken in solvent. Accordingly, the coating retains 90.2% of its mass after 100 sand‐impact cycles, yet redisperses within 10 s and undergoes ten stripping–recovery–respraying cycles with stripping recovery above 97% in each cycle. As a representative functional validation, the coating heats by 25.83°C under 0.5 sun at −10°C and delays complete freezing to 732 s while reducing ice adhesion. This work illustrates a material design strategy combining structural complementarity, composition control, and reversible interactions for service stability with practical recovery and reuse in application scenarios where both are required.