Hybrid nanoparticles with continuously tunable scattering length density for the analysis of phase separation in mixed colloidal systems*

The modification of nanoparticle surfaces with polymeric chains has emerged as effective tool to control the interactions and assembly behavior of colloidal systems. Recent results have shown that interactions between chemically distinct polymeric ligands can drive the phase separation of mixed particle systems. This provides opportunities for the fabrication of microstructured hybrid materials that derive functionality from the organization of nanoparticle constituents into microscopic domains.
We will present recent results on the phase separation behavior of polymer tethered particles in thin films. In the thin film state, phase separation resembles the corresponding linear polymer blends provided the length of polymer ligands exceeds a threshold value. However, domain growth kinetics differs from the prediction for diffusion-controlled systems. To elucidate the origin of this deviatory behavior, small angle neutron scattering is performed in the bulk state. A method enabling the continuous variation of the scattering length density of nanoparticles will be presented and its application to the SANS analysis of phase separation in mixed brush particle systems will be demonstrated.