8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P3.4Fri 911:10-14:00Undulation instabilities in the meniscus of liquid crystalmembranesPhilippe Cluzeau, 1 Jean Christophe Loudet, 1 P. Patricio, 2 and Pavel Dolganov 31 Université Bordeaux 1, CRPP, CRPP, 115 Avenue Schweitzer, 33600, Pessac,France2 Universidade de Lisboa, Lisboa Codex, Portugal3 Institut of solid state physics, Chernogolovka, Russian FederationYou need not be a scientist to notice that the surface of a liquid drop, such as a water drop, isperfectly smoot. Yet, in the case of complex fluids like liquid crystal, this is not always so: A weirdfinger-like structure composed of well aligned stripes may show up under certain conditions. Wediscovered that those stripes actually correspond to an undulation of the liquid crystal air interfacewhich is then no longer smooth but rather wrinkled and rugged. This phenomenon occurs in themeniscus of liquid crystal membranes obtained with lamellar phases of liquid crystal [1], like thesmectic-C or smectic C* phase. Using optical microscopy, phase shifting interferometry [2], andatomic force microscopy, we characterize the undulated structures which appear in the meniscusof free standing smectic-C* films. We demonstrate that these periodic structures correspond toundulations of the smectic-air interface. The resulting striped pattern disappears in the untiltedsmectic-A phase. The modulation amplitude and wavelength of the instability both depend onmeniscus thickness. We study the temperature evolution and propose a model that qualitativelyaccounts for the observations [3]. Last, it is interesting to note that the biological membranes ofliving cells share common features with our LC membranes: They are also elastic media madeof thin layers of organized liquids. The reported results open up new perspectives for a betterunderstanding of their highly complex machinery.[1] K. Harth and R. Stannarius, Eur. Phys. J. E, 2008-10404-6 (2009).[2] D. W. Robinson and G. T. Reed, Interferogram analysis (Institute of Physics Publishing,Bristol) (1993).[3] J. C. Loudet, P. V. Dolganov, P. Patr?cio, H. Saadaoui, and P. Cluzeau, Phys. Rev. Lett. 106,117802, (2011).4