(15b) Structure and Dynamics of Frictional Vs. Frictionless Colloidal Gels

Functional materials of diverse types can be fabricated through dispersions of colloids. Attractive colloids at intermediate volume fractions can form amorphous space-spanning networks, exhibiting macroscopic mechanics of a viscoelastic solid that are commonly referred to as gels. Gel properties ultimately originate from the microscopic interactions at the particle level that are results of features including the surface functionality and surface topography of the particles. In most studies, the interactions between particles are modeled to be central, where attractive/repulsive forces are aligned with the centerline between two particles. However, in cases where particles having rough surfaces, noncentral forces (e.g., friction) become influential. In this presentation, I will discuss the formation of space-spanning particulate networks of attractive frictional and frictionless colloids, with an emphasis on the structural features of the resulting gels and their network characteristics. This is followed by rheological characterization of the gels and correlating the microscopic features and forces to macroscopic mechanics of the system.