Free standing smectic films have been investigated at the transition from the smectic- C phase to the isotropic phase. In the vicinity of the bulk transition temperatures, isotropic droplets of micrometer size appear in the film. Such systems represent convenient models for anisotropic, two-dimensional emulsions. A characteristic feature of the droplets is their mutual interaction by elastic distortions of the local orientation of the film, the c director, which are related to the anchoring conditions of the c director at the droplet border. We describe in detail the director deformations created by isotropic droplets of different sizes, and their role in the spontaneous organization of regular droplet patterns. Depending upon droplet size and anchoring strength, topological defects can be induced in the c -director field. Qualitative differences to literature data on cholesteric droplets in smectic- C* films are discussed.

The temporal evolution of an interface between glycerin and a glycerin-sand suspension of small packing fraction (obtained using the hindered settling phenomenon) driven by gravity is experimentally investigated. The growth rates for the different wave numbers characterizing the developing front are determined by means of a Fourier analysis. To model the observed behavior, we apply the idea of the Rayleigh-Taylor instability for a homogeneous fluid with vertically varying density and viscosity (one-fluid model). A good agreement between the experimental and theoretical results is obtained.

A high-pressure technique is introduced which allows a continuous variation of the inclusion size in liquid crystal colloids. We use a nematic liquid crystal host into which micrometer-sized gas bubbles are injected. By applying hydrostatic pressures, the diameter of these gas bubbles can be continuously decreased via compression and absorption of gas into the host liquid crystal, so that the director configurations around a single bubble can be investigated as a function of the bubble size. The theoretically predicted transition from a hyperbolic hedgehog to a Saturn-ring configuration, on reduction of the particle size below a certain threshold, is confirmed to occur at the radius of a few micrometers.

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