Influence of molecular weight on the distribution of segmental relaxation in polymer grafted nanoparticles

The segmental dynamics of one-component nanocomposites (OCNC) is significantly influenced by the molecular weight (M-w) of the grafted polymer. Neutron backscattering shows that compared to the neat polymer the OCNCs exhibit a shift from slower segmental dynamics at low Mw to faster dynamics at high M-w. We model the local relaxation as distribution of exponential diffusers. This approach reveals the presence of fast and slow segments in both OCNCs. However, their fractional contribution varies with M-w leading to different average relaxation times. Our results present important insights into the origin of segmental mobility in OCNC and address the inconsistencies in different literature reports.