Phase separation and anomalous domain growth in binary blends of polymer-grafted nanoparticles

Surface modification of nanoparticles with polymer ligands has emerged as an important strategy to control interactions and assembly in colloidal systems. Recent research has revealed that the tethering of polymeric ligands to the surface of nanoparticles (so called ‘particle brush’) can induce the autonomous organization of multicomponent particle brush mixtures into monotype domain structures in a process that bears similarity to phase separation in binary polymer blends.

In this contribution, results on the phase separation behavior and kinetics of particle brush blends comprised of organosilica grafted with poly(methyl methacrylate) (PMMA) and poly(styrene-r-acrylonitrile) (PSAN), respectively. Two stages of domain growth are observed: a first regime that is characterized by scaling coefficient d ~ ??^0.2 and a second regime featuring d ~ ??^0.3 (where d denotes the domain size). Electron imaging and neutron scattering are used to verify domain growth kinetics in thin film and bulk specimen. The results are interpreted in terms of ‘anomalous growth behavior’ that has been predicted for entangled polymer blends. The results point to new opportunities for harnessing ligand interactions in brush particle systems for the fabrication of microstructured hybrid materials.