Facile fabrication of fluorine-free, transparent and self-cleaning superhydrophobic coatings based on biopolymer castor oil

A highly transparent self-cleaning superhydrophobic surface was constructed via a facile and environmentally friendly strategy by using biomass-based polyurethane and fused SiO2 nanoparticles. By simply controlling the amounts of castor oil (CO) and SiO2, the coating presented excellent superhydrophobic with high water contact angle (158.5 degrees) and low sliding angle (3.9 degrees), as well as the transmittance of the coating was above 80% in visible-light region. Moreover, the coatings showed remarkable robustness against abrasion of 5 cycles without an apparent decrease of superhydrophobicity and possessed excellent self-cleaning properties against dirty contaminant. Therefore, such transparent and self-cleaning superhydrophobic coating could make it an ideal material for application in optoelectronics, liquid-repellent coatings, and oil-water separation. (C) 2018 Elsevier B.V. All rights reserved.