Self-stratifying amphiphobic coating based on functional polyacrylates

Abstract Self-stratifying coating is a promising and interesting coating system containing multi-resinous components, which instinctively stratify after coating on the substrate. Here, we have developed a new type of self-stratifying coating based on functional polyacrylate system. In this case a terpolymer of butyl acrylate, acetoacetoxy ethyl methacrylate and hydroxyethyl methacrylate was used as the polymer matrix. The whole coating system consists of a blend of a functional acrylic terpolymer (bearing acetoacetoxy, n-butyl as well as hydroxy ethyl functional group as the pendant group), phenyl methoxy functional siloxanes, hollow glass spheres (HGS) and aerogel particles (AP). 3-aminopropyl triethoxysilane was used as a crosslinker. Hydrophilic hollow glass spheres (of 20 μm average particle size) and hydrophilic aerogel particles (of 5 μm average particle size) were used to generate desirable roughness on the surface. Low quantity of a non-silanated fluorinated surfactant was incorporated, which self-stratifies to the surface during coating film formation and imparts oleophobicity. An oil and water repellent (amphiphobic) surface was developed with high water as well as diiodomethane contact angle (∼130°) by varying the ratio of glass spheres and aerogel to each other and the polymer. Rolling effect of water and oil drops was also prominently visible. The surface showed excellent resistance to polar and non-polar solvents, good resistance to heat (150 °C) and sand impingement after which the water contact angle remains unchanged. The oil repellency was easily restored by spraying or dipping in a dilute solution of the non-silanated fluorinated compound. This coating can be applied by conventional techniques such as spray application and can have potential applications in anti-soiling and self-cleaning coatings.