Dynamics of star polymers: Evidence for a structural glass transition

Abstract

The dynamics of an 18-arm poly(isoprene) star polymer ${(M}_n^{\mathrm{arm}}$=7360 g/mol) is investigated by dynamic light scattering and viscometry. Above the overlap concentration $c^{*}$ the intensity autocorrelation functions show a two-step decay, which implies the existence of long range correlations, $\xi \approx 100$ nm. A similar length scale can be derived from the $q$ dependence of the static scattering intensity, which reveals a strong excess scattering at low $q.\mathrm{}$ These experimental results are an indication for a structural glass transition at higher concentrations as known from colloidal systems.