Materials Science & Processing Partial structure factors in star polymer/colloid mixtures

Abstract. Addition of polymer to colloidal suspensions in-duces an attractive part to the colloid pair potential, which is of purely entropic origin (“depletion interaction”). We in-vestigated the influence of polymer branching on depletion forces by studying mixtures of hard sphere colloids and star polymers with increasing arm number f = 2–32, but con-stant Rg ≈ 500 Å. We found a pronounced effect of branching on the position of the gas/liquid demixing transition. Using small angle neutron scattering (SANS) we were able to meas-ure partial structure factors in star polymer/colloid mixtures. The relative distance to the demixing transition is reflected in our scattering data. PACS: 61.12.Ex; 61.25Hq; 82.70Dd Typically, soft matter systems almost always occur in the form of mixtures. Thus, the inherent features of mixtures, lik