Brownian dynamics modeling of colloidal assembly on curved interfaces subject to isotropic and anisotropic electrostatic interactions

Understanding and manipulating the assembly dynamics of colloidal particles confined at a fluid interface is important for many chemical and biological processes. Brownian motion, interface curvature, and interparticle forces are among the most important factors affecting particle dynamics and assembly structures on the interface. In this research, a new Brownian dynamics algorithm is exploited to simulate microparticle dynamics on curved surfaces of arbitrary geometries that cannot be parametrized analytically. The particle motion is modeled on the discretized triangular mesh using a velocity-folding scheme. We explore the particle behaviors on surfaces with uniform and non-uniform curvatures, including sphere, oblate, prolate, and geometrically controlled sessile droplets. We systematically investigate the effects of relative particle size, particle concentration, and interparticle interactions on the dynamics and associated assembly structures. Inspired by experiments, we particularly focus on the assembly dynamics of charged colloids subject to isotropic electrodipping attraction or anisotropic in-plane dipolar attractions due to inhomogeneous surface charge. These cases are also compared with the systems of uncharged particles interacting through capillary multipoles.