Geometric Effects of Colloidal Particles on Stochastic Interface Adsorption.

The stochastic interface adsorption behaviors of ellipsoid particles were investigated using optical laser tweezers. The particles were brought close to the oil-water interface, attempting to attach forcefully to the interface. Multiple attempts of the particle attachments statistically quantified the dependence of the adsorption probability on the particle aspect ratio. It was found that the adsorption probability proportionally increased with the aspect ratio because of the decrease in electrostatic interactions between the charged particles and the charged interface for higher aspect ratio particles. In addition, the adsorption holding time required for the interface attachments was found to increase as the aspect ratio decreased. Notably, the probabilistic adsorption behaviors of the ellipsoid particles and the holding time dependence revealed that the particle adsorption to the interface occurred stochastically, not deterministically. We also demonstrated that the adsorption behaviors measured on a single-particle scale were consistent with the gravity-induced spontaneous adsorption properties performed on a large scale with regard to the nondeterministic adsorption behaviors and the aspect ratio dependence on the adsorption probability.