Growth of a self-assembled monolayer by fractal aggregation

Abstract

Atomic force microscope images show that self-assembled monolayers of octadecyltrichlorosilane form on mica by nucleating isolated, self-similar domains. With increasing coverage, the fractal dimension of the growing domains evolves from 1.6 to 1.8. At higher coverage, continued growth is limited by adsorption from solution. Monte Carlo simulations that include, for the first time, adsorption as well as surface diffusion qualitatively reproduce both the growth kinetics and evolution of fractal structure, much better than a two-dimensional diffusion-limited-aggregation model.