Microscopical structure of the uniaxial and biaxial lyotropic nematics

High‐resolution x‐ray measurements have been performed at the synchrotron of LURE (Orsay) to study both uniaxial (discotic and calamitic) and biaxial nematic lyomesophases of the mixture K‐laurate, 1‐decanol, and D2O. The variations of the densitometric profiles of the diffracted bands are analyzed vs temperature. They are shown to be consistent with the model of similar micellar aggregates in the three nematic phases, undergoing different orientational fluctuations. It is moreover discussed that the micelles have, on the average, the shape of biaxial platelets with a (1/2/3) anisotropy, and that they build the same pseudolamellar structure in each nematic phase.

[1]  A. Saupe,et al.  Electric conductivity measurements on the nematic states of a micellar solution of potassium laurate/1‐decanol/D2O , 1986 .

[2]  C. Rosenblatt.  Micellar shape distribution in the isotropic phase near a prolate-to-oblate nematic phase transition , 1986 .

[3]  Hendrikx,et al.  Uniaxial-biaxial phase transition in lyotropic nematic solutions: Local biaxiality in the uniaxial phase. , 1986, Physical review. B, Condensed matter.

[4]  Y. Galerne,et al.  Temperature and concentration range of the biaxial nematic lyomesophase in the mixture potassium laurate/1-decanol/deuterium oxide , 1985 .

[5]  A. Levelut,et al.  Pseudo-lamellar ordering in uniaxial and biaxial lyotropic nematics : a synchrotron X-ray diffraction experiment , 1985 .

[6]  A. Levelut,et al.  Biaxial Nematic Lyomesophase Studied by X-Ray Diffraction , 1985 .

[7]  Y. Galerne,et al.  Critical slowing down of biaxiality fluctuations at the uniaxial-to-biaxial phase transition in a lyotropic disklike nematic liquid crystal , 1984 .

[8]  A. Levelut.  High resolution X-ray diffraction study of Smectic A - Smectic A phase transitions in a binary mixture of polar thermotropic liquid crystals , 1984 .

[9]  J. Deutch,et al.  Biaxial nematic phase, multiphase critical point, and reentry transition in binary liquid crystal mixtures , 1984 .

[10]  Y. Galerne,et al.  Temperature behavior of the order-parameter invariants in the uniaxial and biaxial nematic phases of a lyotropic liquid crystal , 1983 .

[11]  M. Rawiso,et al.  Anisotropic aggregates of amphiphilic molecules in lyotropic nematic phases , 1983 .

[12]  W. Gelbart,et al.  Phase Diagram Behaviors for Rod/Plate Liquid Crystal Mixtures , 1982 .

[13]  L. W. Reeves,et al.  New lyotropic liquid crystals composed of finite nonspherical micelles , 1981 .

[14]  A. Saupe,et al.  Observation of a Biaxial Nematic Phase in Potassium Laurate-1-Decanol-Water Mixtures , 1980 .

[15]  E. Samulski,et al.  Lyotropic nematics : molecular aggregation and susceptibilities , 1979 .

[16]  A. Martinet,et al.  Coupling between nematic lyomesophases and ferrofluids , 1979 .

[17]  K. Mittal,et al.  Solution Chemistry of Surfactants , 1979 .

[18]  A. Tracey,et al.  Effect of counterion substitution on the type and nature of nematic lyotropic phases from nuclear magnetic resonance studies , 1976 .

[19]  R. Alben.  Liquid crystal phase transitions in mixtures of rodlike and platelike molecules , 1973 .

[20]  P. G. de Gennes,et al.  Theory of magnetic suspensions in liquid crystals , 1970 .

[21]  V. Luzzati,et al.  La structure des colloïdes d'association. I. Les phases liquide–cristallines des systèmes amphiphile–eau , 1960 .