Interfacial Properties and Hopping Diffusion of Small Nanoparticle in Polymer/Nanoparticle Composite with Attractive Interaction on Side Group

The diffusion dynamics of fullerene (C [Formula: see text]) in unentangled linear atactic polystyrene (PS) and polypropylene (PP) melts and the structure and dynamic properties of polymers in interface area are investigated by performing all-atom molecular dynamics simulations. The comparison of the results in two systems emphasises the influence of local interactions exerted by polymer side group on the diffusion dynamics of the nanoparticle. In the normal diffusive regime at long time scales, the displacement distribution function (DDF) follows a Gaussian distribution in PP system, indicating a normal diffusion of C [Formula: see text]. However, we observe multiple peaks in the DDF curve for C [Formula: see text] diffusing in PS melt, which indicates a diffusion mechanism of hopping of C [Formula: see text]. The attractive interaction between C [Formula: see text] and phenyl ring side groups are found to be responsible for the observed hopping diffusion. In addition, we find that the C [Formula: see text] is dynamically coupled with a subsection of a tetramer on PS chain, which has a similar size with C [Formula: see text]. The phenyl ring on PS chain backbone tends to have a parallel configuration in the vicinity of C [Formula: see text] surface, therefore neighbouring phenyl rings can form chelation effect on the C [Formula: see text] surface. Consequently, the rotational dynamics of phenyl ring and the translational diffusion of styrene monomers are found to be slowed down in this interface area. We hope our results can be helpful for understanding of the influence of the local interactions on the nanoparticle diffusion dynamics and interfacial properties in polymer/nanoparticle composites.