Potential of mean force and underscreening of polarizable colloids in concentrated electrolytes

Abstract: This study uses advanced numerical methods to estimate the mean force potential (PMF) between charged, polarizable colloidal particles in dense electrolytes. We observe that when the Debye screening length, $\lambda_{\mathrm{D}}$, is below the hydrated ion size, the PMF shows discernible oscillations of purely electrostatic origin as opposed to chemical affinity, in addition to the expected decay in DLVO theory. Moreover, our findings suggest concentrated electrolytes are significantly less efficient at muting electrostatic interactions in electrostatically stabilized colloidal suspensions, potentially having significant implications for our understanding of colloidal stability and the forces that govern the behavior of concentrated charged soft matter systems beyond DLVO theory.