Integration of Cation–π Interactions with Polyphenols for Super‐Hydrophilic Coatings

Abstract Cation–π interaction is one of the most important noncovalent interactions found in biosystems, which has attracted great interests for the engineering of functional materials. In this work, one‐step assembly of super‐hydrophilic coatings via surface modification with polyphenols and cations is reported based on cation–π interactions. Hydrophilicity of surface coatings is tunable by the variation of cations based on the different affinity between polyphenols and cations. Copper meshes coated with tannic acid and tetramethylammonium demonstrate super‐hydrophilicity and high stability due to the strong cation–π interaction between catechol/pyrogallol and cations. The super‐hydrophilic coatings show high oil breakthrough pressure, self‐cleaning, and anti‐fogging properties, which can efficiently separate the mixture of oil and water. This study provides an avenue to explore the cation–π interactions for super‐hydrophilic coatings.