DEVELOPMENT OF PHASE MORPHOLOGIES OF POLY(METHYL METHACRYLATE) POLYSTYRENE TOLUENE MIXTURES IN ELECTRIC-FIELDS

The evolution of the phase morphology of polystyrene (PS)-poly(methyl methacrylate)(PMMA) blends during solvent casting from toluene solutions in an electric field was studied. Depending on the sizes of the phases and the electric field strength used, ellipsoidal or columnar structures could be obtained. If the field was removed while a considerable amount of solvent was present, columnar structures broke up into spherical phases via the Rayleigh instability. Partial phase diagrams were constructed for the PMMA-PS-toluene system by experimental determination of tie lines and by theoretical simulation of spinodal curves. Dielectric constants, viscosities, and interfacial tensions (using the pendant drop technique) were measured for some of the coexisting phases. Interfacial tensions calculated using the shapes of deformed drops in electric fields were very low (10(-5)-10(-4) dyn/cm), 2-3 orders of magnitude smaller than those measured by the pendant drop method. Possible reasons for this difference are discussed.