Smectic Membranes in Aqueous Environment

Smectic Membranes in Aqueous Environment

Smectic films which are freely suspended on a solid frame in air are well established experimental model systems for the study of the structure of smectic phases, phase transitions in two dimensions, and surface and dimensionality effects in fluid systems. We could prepare freely suspended smectic films in water with a size of 1 cm2 using surfactants ensuring a strong homeotropic anchoring at the smectic/water interfaces. Since the ordering surface field at the smectic/water interface can be tuned via the surfactant coverage, smectic films in aqueous environment may expand the general range of possible studies of freely suspended smectic films. We study the stability and the thinning transitions which occur at temperatures above the volume smectic-A - isotropic transition temperature.

Isotropic liquid crystals might be used as carrier liquids for aqueous droplets in digital microfluidics. The smectic surface order in the isotropic temperature regime could provide a handle to control the stability of the membranes separating the water droplets. Forced electrocoalescence studies in microfluidic channels indicate an enhanced stability in the temperature range where a smectic surface order exists:

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Smectic membranes in aqueous environment
Y. Iwashita, S. Herminghaus, R. Seemann, and Ch. Bahr, Phys. Rev. E 81, 051709 (2010).
DOI: 10.1103/PhysRevE.81.051709

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