Understanding crystallization pathways through in situ characterization and theory

The potential of a general synthetic approach for multiscale structural control by manipulating the interfacial nucleation and self-assembly of nanoscale building blocks is demonstrated using an integrated theoretical and experimental approach. The control over crystallization pathways across different length scales is demonstrated using two classes of nucleation and growth processes: crystallization on well-defined surfaces, and seeded growth of metal and metal oxide nanostructures. The developed theoretical framework for modeling interfacially directed crystallization pathways and a suite of in situ characterization techniques for monitoring nucleation and crystal growth processes were used to show that the interfacial solvent structure and ion distributions are critical controls for surface-directed nucleation. Using a model system of gold nanoparticles, we have shown that the correlated fluctuation dynamics of growth solutions in the interfacial region largely dictate nucleation and growth pathways in seeded growth processes. Applying these principles to more complex systems and utilizing interfacial surfactant templating and temperature-induced phase transformations in surfactant templates produced highly regular 3D porous materials.