We present results of pulsed field gradient nuclear magnetic resonance (PFG NMR) measurements of restricted diffusion of silicone oil (PDMS) dispersed in the continuous polystyrene phase of a two-phase system containing polystyrene (PS) and poly(dimethylsiloxane). These materials were synthesized by free-radical polymerization of styrene in a silicone oil/styrene emulsion in the presence of a polystyrene-poly(dimethylsiloxane) (PS-PDMS) block copolymer acting as an emulsifier. The diameters of the oil droplets could be derived from the echo attenuation plots of the PFG NMR experiments. They decrease with increasing temperature. The materials were observed to possess a thermally stable structure up to temperatures of 160 degrees C.