From Maya blue to biomimetic pigments: durable biomimetic pigments with self-cleaning property

The inferior stability of most Maya blue-like pigments to ancient Maya blue seriously hinders their practical applications. Inspired by self-cleaning and water-repellent properties of the lotus leaf in the natural world, biomimetic superhydrophobic pigments with high contact angles and ultralow sliding angles for various aqueous solutions were fabricated by combining palygorskite, cationic dyes, and organosilanes. Superhydrophobicity of the pigments is closely related to their topography and chemical composition, which can be regulated simply by changing the concentrations of organosilanes. The superhydrophobic pigments feature an excellent self-cleaning property and high stability under various conditions owing to an air cushion at the solid-liquid interface and a shielding effect of the chemically inert coating based on organosilanes. Moreover, durable superhydrophobic pigments of various colours can be easily prepared using different cationic dyes and applied onto various substrates via the same procedure.