Confinement-induced deviation of chain mobility and glass transition temperature for polystyrene/Au nanoparticles

摘要

The mobility and glass transition temperature (T_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 T_g by DSC for thiolated polystyrene (PS-SH) on gold nanoparticles. The increase in T_g and signal suppression in NMR spectra clearly indicate that the surface confinement dominates molecular mobility as well as T_g. The molecular weight of PS-SH and nanoparticles size show significant influence on the immobilization and T_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.