Effect of Attractive Forces on the Slow Dynamics of Colloidal Suspensions and Supercooled Liquids

The role of attractive interactions on emergent glass and gel-like dynamics in thermal liquids and colloidal suspensions is of wide interest. Existing microscopic theories based on local cage scale physics where dynamical constraints enter only via the structural pair correlations have not been able to explain a number of aspects of activated dynamics in dense attractive fluids. We construct a microscopic theory based on real forces and pair structure for these systems within the framework of the Elastically Collective Nonlinear Langevin Equation approach which treats structural relaxation as a coupled local-nonlocal event involving cage scale large amplitude hopping and longer range facilitating elastic fluctuation. The influence of the functional form and spatial range of the interparticle attraction on activated relaxation, glass melting, and attractive glass and dense gel formation have been analyzed. Various dynamical features are shown to be strongly dependent upon the precise form of the microscopic forces (e.g., LJ versus exponential attractions), including dynamical re-entrancy.