Spontaneous Growth of Two-Dimensional Complex Patterns of Nanoparticles at Model Molecular Surfaces

Abstract

Imposed anisotropy of either physical or geometrical origin is known to be a determining parameter in the emergence of complex patterns (fractals, dendrites) in organizing matter (crystallization, growth of bacterial colonies). In such systems, any local gradient in a physicochemical parameter or broken symmetry may result in complex growth shapes. In contrast, the formation of self-organized complex patterns at, say, molecularly smooth and chemically homogeneous surfaces in a uniform and structureless solution of monosized particles constitutes a rare and incompletely explored phenomenon. We here report on such spontaneous emergence of two-dimensional treelike patterns of nanogold particles that are adsorbed from aqueous dispersions, at both homogeneous and mixed self-assembled molecular surfaces. These results provide a new picture on the connection between wetting dynamics, interface instabilities, and the spontaneous formation of complex patterns at chemically homogeneous and anisotropy-free surfaces....