Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA.
J Chem Phys. 2010 Jul 21;133(3):034709. doi: 10.1063/1.3455232.
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.
使用动态模拟研究了球形胶体在均匀和带电图案表面上吸附的动力学、表面结构和表面覆盖率。开发了一种布朗动力学模拟方法，以考虑颗粒和吸附表面之间的双电层和范德华相互作用，以及单个颗粒的布朗运动。基于非线性泊松-玻尔兹曼方程的渐近解来确定颗粒-颗粒相互作用和颗粒-壁相互作用。比较了在表面迁移率可忽略（随机顺序吸附）和有限表面迁移率条件下胶体吸附的极限情况，并发现表面覆盖率的相对程度取决于双电层相互作用的强度。还研究了带电条纹、正方形和圆形图案上的吸附，发现条纹和正方形图案比圆形图案诱导更高的有序度。通过从胶体颗粒的双分散混合物中吸附的模拟说明了胶体吸附中多分散性的重要性。这些动态模拟表明，在所有情况下，动力学对于由本征非平衡胶体吸附过程形成的表面结构都很重要。
