Effects of a nanoscopic filler on the structure and dynamics of a simulated polymer melt and the relationship to ultrathin films.

We perform molecular dynamics simulations of an idealized polymer melt surrounding a nanoscopic filler particle. We show that the glass transition temperature T(g) of the melt can be shifted to either higher or lower temperatures by tuning the interactions between polymer and filler. A gradual change of the polymer dynamics approaching the filler surface causes the change in the glass transition. We also find that polymers close to the surface tend to be elongated and flattened. Our findings show a strong similarity to those obtained for ultrathin polymer films.