Effects of nanoparticles on chain dynamics and glass transition in athermal polymer nanocomposites

Chain relaxation dynamics and the glass transition of mixtures of polystyrene (PS) homopolymer with PS-grafted gold nanoparticles were examined using broadband dielectric spectroscopy, differential scanning calorimetry and capacitive scanning dilatometry. Through changes in the nanoparticle core size, D, grafting density, $\sigma $, degree of polymerization of grafted chains, N, and the nanoparticle concentration, $\phi $, both the chain relaxation time, $\tau $, and the T$_{g}$ could be induced to undergo significant changes, increases or decreases, in magnitude. These results will be discussed in light of dynamics in other polymer/nanoparticle systems. In addition, the role of particle size and the role of the melt/brush interfacial interactions on the dynamics will be discussed.