(345b) Brownian Particle Adsorption At Fluid-Fluid Interfaces: The Effects of Geometry and Surface Roughness

Via detailed molecular dynamics simulations we study the adsorption of Brownian particles at a fluid-fluid interface. In the present study, we focus on the technologically important case of Brownian particles that exhibit a discontinuous or irregular surface morphology. We observe that the position of the center of mass and the angular orientation of the studied particles can present a multiplicity of metastable states. The observed metastable states correspond to local minima in a nontrivial landscape of the system free energy. The presence of multiple metastable states can significantly retard, or even prevent, the relaxation to a state of minimum free energy that is predicted by continuum theory for ideally smooth particles. We find that the shape and size of the microscale roughness of the particle determine the energy barriers between observed metastable states and the particle mobility at the interface. These results shed important insights in the dynamics of colloidal assembly at fluid-fluid interfaces.