Bimodal colloid gels of highly size-asymmetric particles

We report a type of colloidal gel, induced by a minute incremental addition of mutually attractive small particles (size ∼12 nm) to a suspension of highly charged large particles (size ∼500 nm). The gel's morphological behavior does not follow the typical power-law scaling for fractal clusters. Its unique scaling behavior has two distinct power-law indices, based on particle volume fraction. We show the unique scaling behavior arises when nonfractal networks of large particles are bridged by small-particle clusters, which occurs between a lower and upper critical boundary of small particle volume fraction.