Pattern and Phase Miscibility Directed-Assembly of Polymer-Grafted Nanoparticles within Polymer Matrix

The modification of nanoparticles with polymer brushes has emerged as an effective way of controlling the interactions and organization of nanoparticles in polymer nanocomposites. Herein we investigate the phase behavior of polystyrene-grafted silica nanoparticles in poly (vinyl methyl ether) (PS-g-SiO₂/PVME) homopolymer blend films, where the graft and matrix polymers exhibit attractive/repulsive enthalpic interactions at low/high temperatures. In ultra thin films (~100nm), phase separation into polymer-grafted nanoparticles (PGNPs) rich and matrix polymer rich phases occurs at a temperature lower than the LCST of classic binary linear polymer blends. Thermal cycling of the blend thin film through the critical temperature enables the reversible formation and dissolution of nanoparticle domain structures. We further illustrate that the PGNPs could be driven into spatially organized sub-micron domains under a symmetry-breaking soft elastomer topographic pattern. Selective segregation of nanoparticle domains is observed in both miscible and immiscible states. Such guided assembly of PGNPs in polymer nanocomposites open pathways to create novel hybrid materials for many technological applications.