Critical adsorption on curved objects

TL;DR

This paper provides a field-theoretic analysis of critical adsorption on curved objects like spheres and rods, revealing distinct behaviors and universality classes, with implications for colloidal flocculation.

Contribution

It introduces a systematic field-theoretic approach to describe critical adsorption on curved geometries, highlighting differences between spherical and rodlike particles and identifying a new universality class for needles.

Findings

Critical adsorption is more pronounced on rods than spheres.

The order parameter profiles depend explicitly on temperature.

Needles form a distinct universality class in critical phenomena.

Abstract

A systematic fieldtheoretic description of critical adsorption on curved objects such as spherical or rodlike colloidal particles immersed in a fluid near criticality is presented. The temperature dependence of the corresponding order parameter profiles and of the excess adsorption are calculated explicitly. Critical adsorption on elongated rods is substantially more pronounced than on spherical particles. It turns out that, within the context of critical phenomena in confined geometries, critical adsorption on a microscopically thin `needle' represents a distinct universality class of its own. Under favorable conditions the results are relevant for the flocculation of colloidal particles.