Kinetics, surface structures, and extent of surface coverage in adsorption of spherical colloids onto uniform and charge-patterned surfaces are studied using dynamic simulations. A Brownian dynamics simulation methodology is developed to account for double-layer and van der Waals interactions between particles and the adsorption surface, in addition to Brownian motion of the individual particles. Pairwise particle-particle interactions and particle-wall interactions are based on asymptotic solutions of the nonlinear Poisson-Boltzmann equation. The limiting cases of colloidal adsorption under conditions of negligible surface mobility (random sequential adsorption) and finite surface mobility are compared, and the relative extent of surface coverage is found to be dependent on the strength of double-layer interactions. Adsorption onto charge-patterned stripe, square, and circle patterns is also examined, and it is found that stripe and square patterns induce a greater degree of order than do the circular patterns. The importance of polydispersity in colloidal adsorption is illustrated via simulation of adsorption from a bidisperse mixture of colloidal particles. These dynamic simulations indicate in all cases the importance of kinetics to the surface structures formed by the inherently nonequilibrium colloidal adsorption process.
Bibliographical noteFunding Information:
Funding from the National Science Foundation (Grant No. CMMI-NIRT 0707610 and GRFP) and the Industrial Partnership for Research in Interfacial and Materials Engineering (IPRIME) is gratefully acknowledged. Computational support and resources provided by the Minnesota Supercomputing Institute (MSI) are also acknowledged.