Superhydrophobic dual-sized filler epoxy composite coatings

Abstract We propose an accessible method of superhydrophobic coating fabrication, in the form of an epoxy resin composite with hard nano- and microfillers, combined with surface sandblasting and wet chemical hydrophobization. The fillers – glass microbeads and Al2O3 nanoparticles, dispersed in the bulk composite – provide a dual-sized roughness, if exposed on the surface. Sandblasting with corundum particles and subsequent air plasma etching exposes and enhances the micro- and nano-scale roughness, while wet chemical modification with 1H,1H,2H,2H-perfluorodecyltrichlorosilane reduces surface free energy to the level required for superhydrophobic materials. The coatings exhibit superhydrophobic behavior, with water contact angle of 152° and contact angle hysteresis of 8°. Hierarchical surface structure of coatings is preserved after erosive wear tests and superhydrophobicity is restored upon re-hydrophobization.