Influence of the microstructure of PPO-based glass-formers on their dynamics as investigated by neutron spin echo

We present a neutron spin echo investigation of the high temperature dynamics of two related glass-forming systems based on poly(oxypropylene): namely the molecular liquid triol and the polyurethane gel. Measurements performed at the first maximum of the static structure factor, on a rather large time window, allow one to analyse precisely the relaxation characteristics of these systems and to compare them with previous neutron time of flight and dielectric results. We discuss the differences in relaxation times and stretching exponents obtained for both samples as a function of their microstructure: molecular nature and architecture (effects of branching or/and three-dimensional network).