Dynamics of dendritic polymers in the bulk and under confinement

The structure and dynamics of a hyperbranched polyesteramide (Hybrane (R) S 1200) polymer and its nanocomposites with natural montmorillonite (Na+-MMT) are investigated by XRD, DSC, QENS, DS and Molecular Dynamics (MD) simulation. In bulk, the energy-resolved elastically scattered intensity from the polymer exhibits two relaxation steps, one attributed to sub-T-g motions and one observed at temperatures above the glass transition, T-g. The QENS spectra measured over the complete temperature range are consistent with the elastic measurements and can be correlated to the results emerging from the detailed description afforded by the atomistic simulations, which predict the existence of three relaxation processes. Moreover, dielectric spectroscopy shows the sub-T-g beta process as well as the segmental relaxation. For the nanocomposites, XRD reveals an intercalated structure for all hybrids with distinct interlayer distances due to polymer chains residing within the galleries of the Na+-MMT. The polymer chains confined within the galleries show similarities in the behavior with that of the polymer in the bulk for temperatures below the bulk polymer T-g, whereas they exhibit frozen dynamics under confinement at temperatures higher than that.