Superhydrophobic/oleophobic coatings based on a catalyst driven thiol‐epoxy‐acrylate ternary system

Abstract

Superhydrophobic surfaces have attracted much attention for their exceptional properties such as self‐cleaning, anti‐fouling, and anti‐fogging. This study presents a facile approach for creating superhydrophobic coatings that are also oleophobic by utilizing spray deposition of polymers mixed with silica particles as an easy and effective route to control the surface roughness of the coatings. The polymer precursors formulated here are based on a ternary thiol‐epoxy‐acrylate mixture that reacts in the presence of a strong base without a need for external initiation (such as light). This system employs tetrafunctional thiol monomers as hubs where both the acrylate and the epoxy components can covalently bond. The acrylate component contains a perfluorinated side chain offering low surface energy properties and the difunctional epoxy monomers crosslink the thiol hubs to provide strength. Addition of a strong base catalyst (1,8‐diazabicycloundec‐7‐ene, or DBU) to the coating precursors initiates the polymerization reaction without the need for light. To identify the optimal formulation, Fourier transformed infrared spectroscopy (FTIR) measurements quantified the kinetics of the polymerization, X‐ray photoemission spectroscopy analysis revealed the surface composition, an optical goniometer evaluated the wetting behavior, and scanning electron microscopy and confocal laser the microscopy provided information about the surface topography of the coatings. Based on the results from FTIR, addition of 0.08 mol % of DBU effectively carries out the reaction within 10 min on the substrate while providing long solution shelf life for the spray coating process. The goniometer results showed that water contact angle of >150°, n‐dodecane contact angle of >110° and diiodomethane contact angle of >130° is achievable upon optimization of the coating precursors. This simple route to create superhydrophobic and oleophobic coatings by spraying may be useful for packaging, protective coatings, and other surface modifications.