Entropy-Driven Phase Transitions in Colloidal Systems

TL;DR

This thesis investigates the kinetic pathways of nucleation and phase behavior in various colloidal systems, employing simulations and theoretical analysis to understand entropy-driven phase transitions and crystallization processes.

Contribution

It provides a comprehensive simulation-based analysis of nucleation pathways and phase diagrams in diverse colloidal particles, including hard spheres, dumbbells, rods, and superballs.

Findings

Different nucleation mechanisms identified for various colloidal shapes.

Phase diagrams mapped for colloidal superballs interpolating from cubes to octahedra.

Micellization behavior of patchy dumbbells influenced by depletion attraction.

Abstract

This thesis can be divided into two independent parts. In the first part of this thesis, we focus on studying the kinetic pathways of nucleation in colloidal systems. In Chapter 2, we briefly introduce the relevant theory of nucleation, i.e., classic nucleation theory. Then in Chapter 3, we investigate the crystal nucleation in the "simplest" model system for colloids, i.e., the monodisperse hard-sphere system, by using three different simulation methods, i.e., molecular dynamics, forward flux sampling and umbrella sampling simulations. Subsequently, we apply our simulation methods to a more realistic system of colloidal hard spheres in Chapter 4. Furthermore, we study the nucleation in a variety of systems consisting of hard particles, i.e., hard dumbbells (Chapter 5), hard rods (Chapter 6), hard colloidal polymers (Chapter 7) and binary hard-sphere mixtures (Chapter 8). In the second part of this thesis, we study the phase behavior of several colloidal systems. In Chapter 9, we study the equilibrium phase diagram of colloidal hard superballs whose shape interpolates from cubes to octahedra via spheres. We investigate the micellization of asymmetric patchy dumbbells induced by the depletion attraction in Chapter 10.