Confinement-Induced Deviation of Chain Mobility and
Glass Transition Temperature for Polystyrene/Au Nanoparticles
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Abstract
The mobility and glass transition
temperature (<i>T</i><sub>g</sub>) 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><sub>g</sub> by
DSC for thiolated polystyrene (PS-SH) on gold nanoparticles. The increase
in <i>T</i><sub>g</sub> and signal suppression in NMR spectra
clearly indicate that the surface confinement dominates molecular
mobility as well as <i>T</i><sub>g</sub>. The molecular
weight of PS-SH and nanoparticles size show significant influence
on the immobilization and <i>T</i><sub>g</sub>. 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