ER Suspensions with ER Active Matrix Liquids

Solutions of polyhexyl isocyanate in xylene, a well known lyotropic liquid crystalline system, are shown to be ER active at concentrations well below those for the onset of a mesophase. This correlates with a field dependent birefringence or orientation induced in the isotropic phase. ER fluids made using these solutions as the liquid phase show an ER activity much greater than just the sum of ER properties of the solutions and the particles in inert fluids, i.e., the effects are synergistic. A greatly enhanced birefringence between the particles is observed under electric field. The effects are explained as due to both a much greater orientation of and increased concentration of polymer between the particles. These effects are not observed for solutions of polystyrene.