Triple-defense design of multifunctional superhydrophilic surface with outstanding underwater superoleophobicity, anti-oil-fouling properties, and high transparency

Superhydrophilic surfaces with underwater superoleophobicity have attracted widely attention in various fields, especially in the frequent ocean oil-spill accidents and increasing industrial oil leakage environments. However, controlling the oil fouling properties on these superhydrophilic surfaces is challenging since the potential solutions to prevent oil fouling tend to interfere with optical transparency. To reconcile the conflict between antioil-fouling properties and transparency, a triple-defense designed strategy by integrating mussel-inspired polycation coating, colorless hydrogel, and mineralized amorphous inorganic materials is introduced to a surface guaranteed superhydrophilicity/underwater superoleophobicity, superior active anti-oil-fouling properties, and high transparency. Thanks to the triple-defense design strategy, a synergistic effect originating from the cooperation of third defense layer of polycation coating, second defense layer of hydrogel, and first defense layer of amorphous inorganic materials gives rise to the superior active anti-oil-fouling properties to this superhydrophilic surface, regardless of oils. Independent of the environment, the surface enables to be aggressively infused by water, thus active de-wetting of diverse oils from the surfaces upon water action. The colorless organic coating and amorphous inorganic materials gives rise to the high underwater transparency. This substrateindependent multifunctional coating can be decorated on diverse substrates, allowing it used in various fields, such as oily wastewater treatment, anti-fogging, and underwater optical devices.