Confinement-Induced Deviation of Chain Mobility and Glass Transition Temperature for Polystyrene/Au Nanoparticles

Abstract

The mobility and glass transition temperature (<i>T</i>_g) for polymers under nanoscale confinement differ substantially from the bulk. Whereas many studies have focused on the one-dimensional confinement, it has great significance to extend studies to higher geometries. Here, we systematically investigate the mobility by dipolar-filter sequence in solid-state NMR and <i>T</i>_g by DSC for thiolated polystyrene (PS-SH) on gold nanoparticles. The increase in <i>T</i>_g and signal suppression in NMR spectra clearly indicate that the surface confinement dominates molecular mobility as well as <i>T</i>_g. The molecular weight of PS-SH and nanoparticles size show significant influence on the immobilization and <i>T</i>_g. Our results can be fitted with a core–two shell model; the inner shell is under strong constraints while the outer shell with less confinement. This work is essential to better understand the confinement effect and also provides a step toward the ultimate desire to tailor the properties of nanomaterials