Facile Fabrication of Durable Superhydrophobic Coatings on SS 304 for biomedical applications

Abstract

A simple and effective method to fabricate durable superhydrophobic coatings by combining shot-blasting and depositing sol-gel nanocomposite coatings on stainless steel SS 304 substrates has been investigated. Shot-blasting was used for two purposes; 1) as a method of physical modification for creating microscale roughness on the substrate and 2) for improving the adhesion of the nanocomposite coatings deposited thereafter. Organic-inorganic hybrid hydrophobic silica sol was synthesized where silica nanoparticles were dispersed using ultrasonication. The silica nanoparticles provided the nanoscaled roughness when the nanocomposite sol was deposited by dip coating on shot-blasted SS 304 surfaces. A micro-nano hierarchical structure on the surface could be created after heat treatment of the coating at 150o C for 1 h, which exhibited superhydrophobicity. Chitosan particles were added to the nanocomposite silica sol to investigate on possible improvement in corrosion resistance and anti-bacterial activity of the superhydrophobic coating. Surface profile, coating morphology of the fabricated surfaces was analysed along with water contact angle and sliding angle measurements to study the surface wettability. The evaluation of the durability and adhesion of the coatings was carried out using weathering tests and scratch resistance measurements. Corrosion and antibacterial resistance of the uncoated and coated samples were analysed. It was found that the nanocomposite coatings deposited on shot-blasted substrates exhibited improved corrosion resistance when compared to uncoated substrates. An anti-bacterial activity of > 90% was obtained for these samples towards the bacterial species E. coli for an exposure time of 30 min and 4 hours.