Surface-directed Spinodal Decomposition on Morphologically Patterned Substrates

TL;DR

This paper investigates surface-directed spinodal decomposition on morphologically patterned substrates, providing numerical insights into domain growth and morphological evolution influenced by substrate patterning.

Contribution

It offers a theoretical analysis of SDSD on chemically homogeneous but morphologically patterned substrates, extending previous work on flat substrates.

Findings

Domain growth behavior inside and above grooves characterized.

Interference of SDSD waves explains morphological evolution.

Numerical results elucidate the impact of substrate patterning on phase separation.

Abstract

This paper is the second in a two-part exposition on {\it surface-directed spinodal decomposition} (SDSD), i.e., the interplay of kinetics of wetting and phase separation at a surface which is wetted by one of the components of a binary mixture. In our first paper [P. Das, P.K. Jaiswal and S. Puri, Phys. Rev. E {\bf 102}, 012803 (2020)], we studied SDSD on chemically heterogeneous and physically flat substrates. In this paper, we study SDSD on a chemically homogeneous but morphologically patterned substrate. Such substrates arise in a vast variety of technological applications. Our goal is to provide a theoretical understanding of SDSD in this context. We present detailed numerical results for domain growth both inside and above the grooves in the substrate. The morphological evolution can be understood in terms of the interference of SDSD waves originating from the different surfaces comprising the substrate.