Self-Assembly of Colloidal Particles at Fluid Interfaces into Complex 2D Structures

Colloidal particles are used to stabilise multiphase liquids by adsorbing to liquid interfaces, but they also serve as model systems for studying self-assembly in two-dimensions. The rich variety of interactions at liquid interfaces, e.g., electrostatic, Van der Waals, and capillary, provide powerful handles for designing self-assembly. In this thesis, we exploit the interplay between particle interactions and particle anisotropy to create complex two-dimensional structures. Specifically, we use finite element simulations and Monte Carlo simulations to study the self-assembly of isotropic and anisotropic colloidal particles at flat and curved interfaces.Firstly, we study the orientation and localisation of single rod-like particles, and the self-assembly of two rods on a cylindrical sessile drop, in both the flotation regime and immersion regime. We show we can control the orientation and self-assembly configuration through the hight of the drop, particle surface chemistry, and particle geometry.Secondly, we study the self-assembly of core-shell spherical particles adsorbed at a flat liquid interface. This system is experimentally found to form complex phases when the system is compressed. Our simulations reproduce all the key features of the experimental phase behaviour and allows us to estimate the underlying soft shell interaction potential.Thirdly, we study the self-assembly of core-shell ellipsoidal particles in the absence of external compression. Experimentally, this system forms chains of side-to-side particles or interconnected triangular lattice structures depending on the particles aspect ratio and shell thickness. Our simulations reproduce experimentally observed self-assembled structures as well as the trend of how these structures evolve with aspect ratio and shell thickness.Finally, we study the self-assembly of polygonal plates with undulating edges, where capillary interactions are controlled purely by the shape of the particles. By using different combinations of polygon shapes and edge undulations, we show that self-assembly can be programmed into the particles through particle shape alone.