An equivalent surface model bridging intermolecular interactions and the normalization of substrate wettability

NM Peng and LL Wang and R Wei and GJ Li and W Jiang and WT Jiang and HZ Liu, PHYSICS OF FLUIDS, 36, 062019 (2024).

DOI: 10.1063/5.0213249

A liquid deposited on a solid surface exhibits various wetting properties, primarily influenced by solid-liquid intermolecular interactions. Achieving a well-estimation of wetting behaviors on textured surfaces remains challenging because the influence of surface textures on intermolecular interactions is unclear. Here, an equivalent surface model is proposed to unify the wettability of both plane and textured substrates through intermolecular interactions. We show that by incorporating intermolecular interactions, lattice structures, and surface topographies, the substrate wettability can be tailored in an equivalent plane with the same average Lennard-Jones potential energy field E. The wettability of one substrate (plane or patterned) is transferred from non-wetting, partial wetting to complete wetting by adjusting the potential well depth of E, epsilon(a). With enhancing epsilon(a), complete wetting is achieved under the critical potential well depth of E, epsilon(ac). Before epsilon(ac), the spreading radius grows as R similar to t(1/1.47) until reaches equilibrium. In this scenario, the equilibrium contact angle theta and spreading factor beta are strongly dependent on epsilon(a), and cos theta is linear to epsilon(a). When exceeding epsilon(ac), complete wetting is achieved, and droplets spread with a precursor film as R similar to t(1/2.3) latterly. This model builds a bridge to link intermolecular interactions and substrate wettability normalization. This strategy offers a framework for substrate surface design and wettability manipulation, catering to applications such as photoresist-drop dispensing in nanoimprint lithography, surface design for grating antifouling, and anti-icing on aircraft surfaces.

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