Long-lasting and stable anti-fog coating combined with active and passive strategy

There is an urgent need to design long-term effective anti-fog coatings to ensure the stabilization of uniform water films on hydrophilic surfaces, considering the impacts of interfacial strength, cyclic drying, and contaminants. Here, we propose an anti-fog strategy that leverages manipulating free volume and hydrogen bonding of hydrophilic networks through the twisted non-coplanar structures, synergized with photothermal effects, to enhance anti-fog efficiency. The introduction twisted non-coplanar structures of 1(2H)-phthalazinone not only significantly enhances the coating's interfacial stability but also increases the molecular free volume, thereby substantially improving its moisture absorption capacity and extending the anti-fogging duration. The developed coating simultaneously achieves high transparency and efficient solar light absorption in the UV/NIR regions, effectively enhancing photothermal fog prevention and removal. The insights into anti-fog strategy promise to translate the structural free-volume benefits measured in laboratories into real-world applications for long-lasting and stable anti-fog coatings. Antifog coatings are of great interest, though it is challenging to balance interfacial strength, cyclic drying, and resistance to contaminants. Here the authors designed a coating using noncoplanar structures to enhance stability and anti-fogging efficiency.