Integration of Cation-π Interactions with Polyphenols for Super-Hydrophilic Coatings

Cation-pi 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-pi 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-pi 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-pi interactions for super-hydrophilic coatings.