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

Fri 911:10-14:00P3.41Novel perforated lamellar-nematic phase in binarymixture of amphiphilic and calamitic liquid crystalsJun Yoshioka, 1 Yoichi Takanishi, 1 Jun Yamamoto, 1 and Isa Nishiyama 21 Kyoto University, Kita-Shirakawa Oiwake-cho, Sakyo-ku, 606-8502, Kyoto, Japan2 DIC Corporation, Saitama, JapanIn the typical lyotropic liquid crystals composed of water and amphiphiles, the water around theaggregates formed by the amphiphiles is an isotropic solvent. In this study, by mixing fluorinatedamphiphilic liquid crystals (BI) and typical calamitic liquid crystals (7CB), we realized the systemwith the aggregates, dispersed in the anisotropic nematic solvent. Then, we have found the’Perforated Lamellar-Nematic (PLN) phase’, which has layer order of lamellar (L) phase and orientationalorder of nematic (N) phase simultaneously embedded on novel microphase-separationstructure by adjusting temperature and mixing ratio. We made the binary phase diagram of theBI-7CB mixture. BI is a c yanobiphenyl liquid crystal with perfluorinated terminal chain. In BIrich region, it shows bilayer structure such as L phase, because the fluorocarbon and the hydrocarbonare immiscible. On the contrary, conventional N phase appears in 7CB rich region, and it isfound the novel PLN phase appears in the region between N and L phases. To analyze the natureof the PLN phase, we used X-ray diffraction and dynamic light scattering (DLS) measurements.From the X-ray, diffraction peaks originated from layer order are observed. On the other hand,from the DLS, relaxation modes attributed to the nematic orientational fluctuations are observed.These results mean both of lamellar and nematic-like behaviors are observed in the PLN phase.Furthermore, measuring concentration dependence of dispersion relation precisely, we found thatthe orientation fluctuation shows purely diffusive hydrodynamic mode, and almost the same asthat in pure 7CB at the 7CB rich limit of PLN. On the contrary, the dispersion relation graduallylost the wave-number dependence as confined in local volume. Thus, we can conclude thattwo-dimensional perforated lamellar structures distributed in 3-dimensionally continuous nematicorder as a structural model of the PLN phase.41