Durable self-cleaning superhydrophobic coatings based on 5 Mg(OH)2·MgSO4·2H2O whisker-SiO2 nanoparticles composites

Abstract

Poor mechanical robustness is a major handicap to the practical application of superhydrophobic coatings. It is imperative to design an effective strategy to improve the durability of superhydrophobic coatings. In this work, we prepared a robust superhydrophobic coating using all-in one suspension that contained magnesium oxysulfate whiskers, SiO2 nanoparticles and amino drying varnish via a drop coating method. The suspension was formed through that a mixture of magnesium oxysulfate whiskers and SiO2 nanoparticles modified by tetraethylorthosilicate and octadecyltrichlorosilane was mixed into amino drying varnish diluted with thinner. The results showed that such inorganic–organic composite modification method could effectively improve the modified effect. The prepared coating displayed excellent water repellency not only on the top surface but also at any exposed internal section throughout the coating, and maintained its superior superhydrophobicity even after the top area was scraped off a layer. Notably, the coating exhibited outstanding self-cleaning capability with a contact angle of 168.81° and a very low sliding angle. Further, amino drying varnish as binders replaced by other common commercial paints could also prepare superhydrophobic coatings. This study can not only facilitate the large-scale fabrication and application of superhydrophobic coatings, but also expand the application filed of magnesium oxysulfate whiskers.