Emulsifying effect of dimethyldioctadecylammonium-hectorite in polystyrene/poly(ethyl methacrylate) blends

An organically modified clay, dimethyldioctadecylammonium-hectorite (DMDO-Hect.), was used as an emulsifier for the immiscible polystyrene/poly(ethyl methacrylate) (PS/PEMA) pair of polymers. The organoclay in this blend adsorbs selectively the PEMA chains and creates PEMA/DMDO-Hect. intercalated structures within which the PS chains are shaped into separate domains. The size of these domains decreases as the concentration of the inorganic DMDO-Hect. partner increases giving a typical emulsification curve that testifies the emulsifying action of the organoclay. SEM and TEM micrographs reveal efficient mixing of the polymers in the presence of the organoclay. The emulsifying action of the organoclay is also reflected by the presence of only one Tg in the DSC thermograms when the organoclay concentration reaches the equilibrium value in the emulsifying curve.