Forces between chemically structured substrates mediated by critical fluids

TL;DR

This paper investigates how chemically patterned substrates influence the critical Casimir forces in binary liquid mixtures near their critical points, using mean field theory to analyze order parameter profiles and effective forces.

Contribution

It introduces a mean field theoretical approach to calculate order parameter profiles and Casimir forces for chemically structured substrates with periodic stripe patterns.

Findings

Casimir amplitudes can be tuned by substrate patterning

Order parameter profiles depend on stripe pattern and relative substrate positions

Effective forces vary with chemical patterning and proximity to critical point

Abstract

We consider binary liquid mixtures close to their critical points confined by two parallel, geometrically flat but chemically structured, substrates. Universal order parameters profiles are calculated within mean field theory for periodic patterns of stripes with alternating preferences for the two species of the mixture and with different relative positions of the two substrates. From the order parameters profiles the effective forces between the two plates are derived. The tuning of Casimir amplitudes is discussed.