Abstract
Self-assembly is one of the most promising strategies for synthesizing functional materials at the nanoscale, such as molecular sieves, nanoelectronics, and photonic crystals. However, despite the many self-assembled nanomaterials that have been made, the criteria to design building components that assemble structures with desired geometry and patterns remain unclear. To tackle this challenge, I study the self-assembly of two colloidal systems: DNA-coated particles and DNA-origami particles. I use a combination of microscopy experiments and computer simulations to study both thermodynamic equilibrium and kinetic pathways. I observe rich yet distinct morphologies and dynamic patterns. For DNA-coated colloidal self-assembly, I investigate the crystallization of a binary colloidal suspension constrained to two dimensions. I observe classical one-step crystallization pathways and non-classical two-step pathways that proceed \textit{via} a solid-solid transformation of a crystal intermediate. I also use enhanced sampling to compute the free energy landscapes corresponding to experiments. I show that thermodynamics alone drive both one- and two-step pathways. For DNA-origami colloidal self-assembly, collaborators and I fold triangular subunits with specific, valence-limited interactions using the DNA-origami technique. These DNA-origami particles assemble into tubules with a self-limited width much larger than the size of an individual subunit. I show there exists a wide distribution in the width and chirality of the assembled tubules, which I rationalize by comparing results with a kinetic Monte Carlo simulation that considers the finite bending rigidity of the assembled structure and the closure kinetics. These results extend our understanding of the relationship between self-assembly pathways and the underlying free energy landscapes of the systems. In addition, they could provide new approaches to controlling the self-assembly of materials made from colloids.