Underliquid wetting behavior of graphene: Is the hypothesis of wetting transparency valid?

Since the inception of wetting transparency hypothesis, understanding the wetting behavior of graphene and its dependence on the choice of underlying support layer fostered significant attention from scientific community. However, wetting studies on submerged graphene coated substrates are relatively scarce despite promising practical applications (e.g. water harvesting, oil-water separation etc.). Here we attempt to understand the wetting characteristics of a monolayer of graphene coated on a glass substrate when submerged in a liquid bath. A wide range of droplet and surrounding liquid combinations have been investigated to assess the dependency on the interaction potentials. In general, partial transparency towards wetting is observed and the degree of the same is seen to demonstrate a non-trivial dependence on the polar and dispersive interaction potentials between the participating entities with the competition between wetting affinities of the droplet and the surrounding liquid with respect to the coated substrate displaying the most prominent effect. Taking cue from Trinavee et al. (Langmuir 2018, 34, 11695−11705), a modified theoretical model involving formation of an intermediate thin film is proposed to explicate this underliquid wetting phenomenon.