8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Wed 711:10-14:00P5.105Coarse-graining of polymer-colloid nanocompositesDaniela Marzi, 1 Barbara Capone, 1 and Christos N. Likos 11 Computational Physics, University of Vienna, Boltzmanngasse 5, 1090, Vienna,AustriaWe investigate the equilibrium and rheological behavior behavior of polymer/colloid nano composites.In particular, we focus on a system of multiarm star polymers mixed with smaller sphericalcolloidal particles.We develop a coarse-graining model to describe the effective interactions of hard colloidal particlesnext to polymer stars, dependent on two main parameters: the size ratio q between colloidalparticles and stars and the number of polymeric arms f. We are mainly interested in the case forwhich colloid is smaller than the polymer star, thereby reverting the usual scenario in which thepolymers act as depletants to the colloids [1]: here, the hard colloids act as small additives to thebig stars.Theoretical considerations of the radial dependence of the osmotic pressure inside a star togetherwith monomer-resolved simulations [2] provide us with a full coarse-grained theory of colloid/starinteractions for a wide range of the parameters q and f. Combined with the known star-star andcolloid-colloid interactions (modeled as hard spheres), the coarse-graining allows us to make predictionsabout the structure of the binary mixture and in particular about the influence of the hardadditives on the structure and rheology of the soft polymers.[1] J. Dzubiella, A. Jusufi, C. N. Likos, C. von Ferber, H. Löwen, J. Stellbrink, J. Allgaier, D.Richter, A. B. Schofield, P. A. Smith, W. C. K. Poon, and P. N. Pusey: Phase separation in starpolymer-colloid mixtures, Physical Review E 64, 010401(R) (2001)[2] A. Jusufi, J. Dzubiella, C. N. Likos, C. von Ferber, and H. Löwen: Effective interactions betweenstar polymers and colloidal particles, Journal of Physics: Condensed Matter 13, 6177-6194(2001)105