Structure of thin film polymer/nanoparticle systems: Polystyrene (PS) coated-Au nanoparticle/tetramethyl bisphenol-A polycarbonate mixtures (TMPC)

The morphologies of thin film blends of polystyrene (PS)-brush coated Au nanoparticles with tetramethyl bisphenol-A polycarbonate (TMPC) were investigated. Our results reveal that entropic effects, associated with the brush/host chain interactions, nanoparticle diameter, D, and asymmetries in monomer sizes of the host and grafted chains, can play a more important role than the favorable PS/TMPC enthalpic interactions toward determining the phase miscibility of the system. A diagram of states is constructed to show the phase separated and dispersed regimes as a function of D, N, the degree of polymerization of the grafted chains, and P, the degree of polymerization of the host chains, at a constant grafting density. These results have important implications on the design of brush coated nanoparticle/homopolymer mixtures for various applications.