(624a) Interaction Forces Between Colloidal Particles within a Nanoparticle Suspension

Atomic force microscopy (AFM) was used to measure the force between a weekly charged colloidal-scale silica sphere and a silica plate in a zirconia nanoparticle suspension at varying nanoparticle concentrations.  Since the effective zeta potential fitting model proposed previously is only applicable for a narrow range colloidal suspension concentrations, an extension of the model based on recently published works for higher nanoparticle concentrations is proposed.  The base assumption for this model is that the nanoparticles should halo around the negligibly charged silica sphere in low nanoparticle concentrations. In this condition, the fitting debye length increases with increasing concentrations. But the nanoparticles tend to be adsorbed onto the silica surface in high concentrations. In this condition, the fitting debye length does not change with the varying concentrations. This assumption is to be proven by fitting this new model to both previously published and new colloidal probe measurements of the nanoparticle haloing system.