Confinement effects on the properties of Janus dimers

TL;DR

This study uses Molecular Dynamics simulations to investigate how confinement influences the phase behavior and self-assembly of Janus nanoparticles, revealing new structures and anomalies not seen in bulk conditions.

Contribution

It demonstrates that geometrical confinement induces novel structural, thermodynamic, and dynamic behaviors in Janus dimers, expanding understanding of their phase diagram.

Findings

New confined structures observed

Reentrant fluid phase under confinement

Density anomaly appears only with confinement

Abstract

Confinement has been suggested as a tool to tune the self-assembly properties of nanoparticles, surfactants, polymers and colloids. In this way, we explore the phase diagram of Janus nanoparticles using Molecular Dynamics simulations. The nanoparticle was modeled as a dimer made by one monomer that interacts by a standard Lennard Jones potential and another monomer that is modeled using a two-length scale shoulder potential. This specific design of nanoparticle exhibits in bulk distinct self-assembled structures and water-like diffusion anomaly. Our results indicate that besides the aggregates observed in bulk, new structures are observed under confinement. Also, the dynamic and thermodynamic behavior of the fluid phase are affected. The systems show a reentrant fluid phase and density anomaly. None of these two features were observed in bulk. Our results show that geometrical confinement leads to new structural, thermodynamical and dynamical behavior for this Janus nanoparticle.