Preparation of superhydrophobic surface with a novel sol–gel system

Abstract

Sol–gel method is a simple and cheap way to prepare superhydrophobic coatings or films, however, most of the researches on sol–gel focus on silica or ZnO sol–gel. The present paper proposes a novel sol–gel which is made from hydrolysis and condensation of the by-product of polymethylhydrosiloxane (PMHS) reacting with γ-aminopropyltriethoxysilane (KH550). The mechanism of formation of the by-product and the sol–gel is discussed and the by-product is characterized by FT-IR. The mass ratio of KH550/PMHS of the sol–gel influences the water contact angle (WCA) and water sliding angle (WSA) of the film made of spraying the sol–gel to microscope glass. When the mass ratio of KH550/PMHS of the sol–gel reaches 0.25, WCA of the corresponding film is 157° and WSA of it is less than 1°. The mechanism of formation of the sol–gel is discussed, and the size of the sol–gel is characterized by polarization microscope as well. The morphology of the film made of the sol–gel is analyzed by means of scanning electron microscope (SEM). It was found that the diameter of the particle of the superhydrophobic film is about 40μm, nevertheless, from the larger magnification picture, the particle is found to be composed of micro-balls whose diameter is about 2μm, and the micro-ball is composed of nano-sphere whose diameter is less than 200nm.