Stuffed onions: Particles in multilamellar vesicles

We have studied the behaviour of mixtures of lyotropic lamellar phases and submicron-size solid particles under shear. Two different lamellar phases were used -an oil-swollen system (SDS, dodecane, pentanol, water) with sterically-stabilised PMMA particles, and an aqueous system (AOT, brine) with charged-stabilised polystyrene particles. Under shear, both systems give rise to multilamellar vesicles or ''onions'' in which the solid particles become encapsulated in the onion cores, as evidenced by optical microscopy. The ''orientation diagram'' and rheological properties of the lamellar + particle systems are not very different from those of the pure lamellae.