NMR analysis of molecular motion of polyurethane ER fluid

Urethane modified polyethers having hard-soft-hard structure were prepared as simple model compounds for homogeneous ER fluids. The NMR relaxation ana lysis was applied to these polyurethane ER fluids, and the molecular motion s and interactions were studied with a series of the data of spin-lattice r elaxation time T-1 and the spin-spin relaxation time T-2. Two hard-soft-har d urethanes, which showed opposite ER effects, were found to have similar r elaxation behaviors under no electric field. The temperature dependence of T-1 indicated existence of significant intermolecular interaction and the c oncentration dependence of T-2 suggested that the molecular interaction mai nly occurs at the polyether main-chain.