Self-assembly of amphiphilic Janus particles at planar walls: A density functional study

TL;DR

This study uses density functional theory to explore how amphiphilic Janus particles organize at planar walls, revealing complex adsorption behaviors and frustration effects driven by anisotropic interactions.

Contribution

It introduces a density functional framework combining Fundamental Measure Theory with mean-field approximation to analyze Janus particle assembly at surfaces.

Findings

Pronounced frustration effects at low temperatures due to anisotropic interactions.

Surface field and interaction competition influence particle adsorption and ordering.

Different wall types affect the adsorption and structure formation of Janus particles.

Abstract

We investigate the structure formation of amphiphilic molecules at planar walls using density functional theory. The molecules are modeled as (hard) spheres composed of a hydrophilic and hydrophobic part. The orientation of the resulting Janus-particles is described as a vector representing an internal degree of freedom. Our density functional approach involves Fundamental Measure Theory combined with a mean-field approximation for the anisotropic interaction. Considering neutral, hydrophilic and hydrophobic walls, we study the adsorption of the particles, focussing on the competition between the surface field and interact ion-induced ordering phenomena. Finally, we consider systems confined between two planar walls. It is shown that the anisotropic Janus interaction yields pronounced frustration effects at low temperatures.