The effects of roughness/texture/patterned surfaces on the apparent contact angles, i.e., on the ‘apparent’ adhesion energy between liquids and solid surfaces, have been studied extensively in the last decade. Although existing models allow for a priori predicting the apparent thermodynamically stable and metastable contact angles, they require extensive mathematical manipulations, and are therefore not commonly used by the scientific community. Instead, the classical and simple to apply Cassie-Baxter and Wenzel models are commonly used to a posteriori analyze contact angle measurements on rough/textured/patterned surfaces. Recently, we derived a more general simple-to-apply wetting model and equation that (1) allows for a priori predicting the thermodynamically and metastable contact angles on textured/rough/patterned surfaces; (2) combines the classical Cassie-Baxter and Wenzel wetting models/equations; (3) includes the effect of surface texture that is outside of the droplet on the apparent contact angle; and (4) can be used to engineer textures that would yield any desirable macroscopic contact angle for a given solid material and two liquids, e.g., oil-water-mineral surface. During the talk, the wetting model will be presented and demonstrated by experiments with crude-oil/brine/core-rock, which is a relevant system for the oil industry. In addition, applications of the model to thermodynamically unstable/metastable states and its relation to contact angle hysteresis and the ability of the system to reach the thermodynamically stable contact angle on textured surfaces will be discussed.

Simple-to-apply wetting model to predict the thermodynamically stable and the metastable contact angles on textured/rough/pattered surfaces

253rd National Meeting (2017)

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