Charged silica suspensions as model materials for liquids in confined geometries

Abstract

Combining computer simulations and experiments we investigate the role of particle charges on the layering behavior of confined silica colloids (slit-pore geometry). To this end we perform colloidal-probe atomic-force-microscope measurements of the oscillatory solvation force of confined suspensions involving three different particle sizes (and resulting total charges). For all systems, the wavelength of the oscillations as function of volume fraction is found to display a power-law behavior characterized by similar exponents. However, the results for different particle sizes cannot be simply mapped onto each other, which demonstrates the importance of correlation effects due to the different Coulomb coupling. Our experimental findings are consistent with the results from parallel Monte Carlo computer simulations of a (DLVO) model system.