Wetting at Non-Planar Substrates: Unbending & Unbinding

TL;DR

This paper investigates fluid wetting on corrugated substrates, revealing an 'unbending' phase transition influenced by substrate geometry, with universal scaling behavior and implications for adsorption properties.

Contribution

It introduces the concept of an unbending phase transition induced by substrate non-planarity, extending interfacial Hamiltonian theory to non-uniform surfaces.

Findings

Unbending transitions can be first or second order.

Unbending critical point exhibits hyperuniversal scaling.

Adsorption at critical point is a universal multiple of planar system.

Abstract

We consider fluid wetting on a corrugated substrate using effective interfacial Hamiltonian theory and show that breaking the translational invariance along the wall can induce an 'unbending' phase transition in addition to unbinding. Both first order and second order unbending transitions can occur at and out of coexistence. Results for systems with short-ranged and long-ranged forces establish that the unbending critical point is characterised by hyperuniversal scaling behaviour. We show that, at bulk coexistence, the adsorption at the unbending critical point is a universal multiple of the adsorption for the correspondent planar system.