Anti-wettability of Chemically and Physically Modified Glass Surfaces

Abstract

The demand for new advanced functional materials has driven scientific work over the past decades. Nature has been inspiring in the creation of different types of self-cleaning and super repellent surfaces mimicking those of plants (lotus leaves), animals (shark skin) or insects (butterfly wings, water strider). To produce and maintain super repellent materials, chemical modification of the surface by using low surface energy materials such as fluoropolymers and/or siloxanes is necessary. Also, physical modification of surface roughness enhances super-repellency against various liquids. The surface roughness can be achieved e.g., by the deposition of nano particles (NPs) using Liquid Flame Spray (LFS). Industrial applications like paper coatings, oil-water separation, and microfluidic devices have benefited from the fabrication of super-hydrophobic surfaces by LFS. In our work, glass substrates were fluorinated by chemical vapor deposition (CVD) method, and others were additionally pre-coated with silica NPs by LFS. The coated glass surfaces were characterized for their anti-wettability by measuring the contact angles of water and compare that to bare glass. The influence of the produced coatings on the wettability of surface with different liquids was examined through measuring advancing/receding contact angles as well as the roll off angle. Results showed that compared to bare glass only fluorination of glass increased the water static contact angle from 18 to almost 112 . This is indicative of hydrophobic behaviour. Coating glass with silica NPs by LFS before fluorination, enhanced the water anti-wetting property for super hydrophobicity. LFS coating provided good oleophobic characteristic.