Hybrid Hydrocarbon/Fluorocarbon Nanoparticle Coatings for Environmentally Friendly Omniphobic Surfaces

The release of fluorocarbons (FCs) into the environment is a growing problem for the chemical industry. Fluorocarbons have been observed in increasing amounts across a range of different locations worldwide on account of environmental release of polymers, consumer products, and a range of other sources. These compounds show long biological half-lives and have been linked to a number of negative toxicological effects. As such, their use should be restricted and eliminated where possible. In this paper, we have shown that the amount of fluorocarbon in omniphobic coatings formed from carboxylate-functionalized nanoparticles can be reduced by as much as 70% without compromising properties such as contact angle hysteresis (CAH) or sliding angle (SA). This reduction is made possible using approaches involving adsorbing hybrid hydrocarbon and fluorocarbon carboxylate chains onto commercially available aluminum oxide nanoparticles. The carboxylates are either coadsorbed onto the same particles, referred to as chemically mixed (CM), or attached to different particles, which we have referred to as physically mixed (PM). Both of these types of surface show enhanced omniphobicity compared to coatings that had been functionalized by the same amount of the fluorinated carboxylate but did not contain any carboxylates bearing hydrocarbon chains. In addition, the sliding properties of synthetic feces on these surfaces were tested in order to investigate the potential applications of this methodology. Similarly, it was observed that the amount of fluorocarbon in the coatings could be substantially reduced without significantly increasing the sliding angle of the mixture on the surface.