Early time wetting kinetics in surface-directed spinodal decomposition for off-critical quenches: A molecular dynamics study

SSH Zaidi and S Suvarna and M Priya and S Puri and PK Jaiswal, JOURNAL OF CHEMICAL PHYSICS, 161, 154703 (2024).

DOI: 10.1063/5.0232743

We present results from the molecular dynamics simulation of surface- directed spinodal decomposition in binary fluid mixtures (A + B) with off-critical compositions. The aim is to elucidate the role of composition ratio in the early time wetting kinetics under the influence of long-range surface potential. In our simulations, the attractive part of surface potential varies as V(z) = -& varepsilon;(a)/z(n), with & varepsilon;(a) being the surface-potential strength. The surface prefers the "A" species to form the wetting layer. Its thickness R-1(t) for the majority wetting (number of A-type particles N-A > number of B-type particles N-B) grows as a power-law with an exponent of 1/(n + 2). This is consistent with the early time kinetics in the form of potential-dependent growth present in the Puri-Binder model. However, for minority wetting (N-A < N-B), the growth exponent in R-1(t) is less than 1/(n + 2). Furthermore, on decreasing the field strength & varepsilon;(a), we recover 1/(n + 2) for a minority wetting case. We provide phenomenological arguments to explain the early time wetting kinetics for both cases.

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