Thioctic Acid‐Grafted Polydopamine Nano‐Crosslinker with Enhanced Photothermal Efficiency

Abstract The development of photothermally responsive smart materials has attracted significant interest due to their broad spectral compatibility and efficient energy conversion capabilities. Polydopamine (PDA) is a prominent bio‐based photothermal candidate that provides a sustainable approach for solar energy utilization. However, its practical integration into advanced photo‐responsive devices is limited by suboptimal photothermal efficiency and interfacial incompatibility with polymer matrices. To address these limitations, a novel photothermal nano‐crosslinker is designed via the covalent grafting of a small amount (<1% molar ratio) of thioctic acid, a natural small molecule, onto the surface of PDA nanoparticle. This approach exhibits exceptional visible‐to‐near‐infrared absorption capabilities and a remarkable photothermal efficiency of 71.4%. The presence of surface carboxyl hydrogen bonds and dynamic disulfide sites facilitates universal compatibility with various polymer matrices through synergistic interfacial bonding mechanisms. The practical application of this photothermal nano‐crosslinker is demonstrated through a series of photo‐driven applications featuring precise spatiotemporal control, such as orthogonally photo‐switchable adhesion and spatially programmable photothermal printing. This robust and versatile photothermal crosslinking strategy establishes a new approach for the rational design of high‐performance photo‐controllable smart materials.