Manipulation of TiO₂ Nanoparticle/Polymer Coatings Wettability and Friction in Different Environments

An AISI 316L surface was functionalized by the adsorption of hydrophilic epoxy and epoxy/TiO₂/epoxy coatings and hydrophobic epoxy/fluoroalkylsilanefunctionalized FASTiO₂/epoxy coatings. We characterized the coatings' wettability, morphology and average surface roughness and discussed the influence of surface wettability and morphology on the coefficient of friction and the wear resistance. Experiments were performed in dry, distilled water and in a simulated physiological solution (Hank's solution). In the case of dry sliding, a lower coefficient of friction is achieved for both TiO₂ coatings compared to the pure epoxy coating. In a water environment the same level of friction is shown for all three coatings, whereas in Hank's solution the friction is reduced for the hydrophilic epoxy/TiO₂/epoxy coating, increased for the hydrophobic epoxy/FASTiO₂/epoxy coating and has no effect on the pure epoxy coating. The results show that the corrosion resistance is significantly improved for the hydrophobic epoxy/FASTiO₂/epoxy coating compared to the hydrophilic pure epoxy and epoxy/TiO₂/epoxy coatings.