Structure and Properties of Nanoparticle Gels

The phase behavior, structure, and viscoelastic properties of high volume fraction nanoparticle-polymer suspensions have been systematically studied through combined experiment and theory in both the equilibrium fluid and nonequilibrium gel states for the first time. Depletion attraction driven gelation induces nanoparticle structural reorganization over many length scales, including the formation of dense, percolated mesoscale clusters. A novel microscopic statistical mechanical theory has been developed and shown to be in good agreement with experiment for both equilibrium collective nanoparticle structure over all length scales and the location of the gel boundary. The theory predicts power law dependences of the gel elastic modulus on attraction strength (polymer concentration), spatial range (polymer size), and nanoparticle volume fraction, which has been experimentally verified in a model system comprised of hard-sphere nanoparticles suspended in a non-adsorbing polymer solution.

Top Paper Award - A. Shah, Y. L. Chen, K. S. Schweizer, C. F. Zukoski, J. Phys. Condensed Matter 15, 4751, (2003)