Preparation of organic–inorganic hybrid methylene blue polymerized organosilane/sepiolite pigments with superhydrophobic and self-cleaning properties

Inspired by the self-cleaning and water-repellent properties of the lotus leaf in the natural world, a kind of organic–inorganic hybrid pigment with superhydrophobic properties was prepared by adsorption of cationic methylene blue (MB) azo dyes onto acid-treated sepiolite (SEP), and then a superhydrophobic functional group of polymerized organosilanes (POSs) obtained from hexadecyltrimethoxysilane (HDTMS) and tetraethoxysilane (TEOS) was introduced onto the composite pigments (MB/SEP). The excellent chemical, thermal and optical stability of MB@POS/SEP are due to the shielding effect caused by the chemical inertness of the POS sheet. Furthermore, the superhydrophobic MB@POS/SEP pigments show an extraordinary self-cleaning property, which is similar to the waterproof property of the lotus leaf and spider web. The superhydrophobicity is strongly linked to their chemical composition and morphology, which can be adjusted by varying the concentration of HDTMS and TEOS. This kind of superhydrophobic pigment can be applied in various fields, such as ceramics, building and daily necessities.