A spontaneous one-step fabrication of slippery gel coatings

Abstract

Lubricant infused surfaces (LIS) have omniphobic repulsion towards most liquids and have applications in various fields. The initial subtractive fabrication methods were multiphase, complex, and substrate limited, requiring specific surface topologies functionalised with fluorosilanes before being infused with low surface tension lubricants. Numerous additive approaches have been developed to overcome these limitations, including chemical, nanoparticle, and polymeric layers. While effective, these coatings still require complex or multi-step syntheses with expensive compounds and substrate limiting fabrication conditions. This paper will present a single-step fabrication methodology for an omniphobic slippery gel coating, predicated on spontaneous urea cross-linking between branched polyethyleneimine and isocyanate bi-terminated perfluoropolyether, with a hydroxy bi-terminated PFPE as both solvent and lubricant. The resulting coatings showed the presence of fluorine and carbon chemistries, and the formation and size of raised island topologies (from the nano – micro range) correlating to the molar ratio of the coating solutions. Extensive examination of the contact and sliding angles of water, canola oil, and n-hexane showed that coatings retained omniphobic properties after numerous lubricant layer removals via pure ethanol. The rapid and facile methodology used to produce the fluorogel coatings allows for an easy transition into larger-scale industrial applications.