New Cholesteric and Nematic Lyotropic Mesophases from Di-Sodium N-Lauroyl-Aspartate |
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Authors: | Maria Regina Alcantara Maria Veronica Marques Correia De Melo Vera Regina Paoli JosÉ Atilio Vanin |
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Institution: | 1. Institute de Química, Universidade de S?o Paulo , Caixa Postal 20780, S?o Paulo, Brasil;2. Departamento de Quimica , Universidade Federal do Rio Grande do Norte , Natal, 59000, Rio Grande do Norte, Brasil |
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Abstract: | Lyotropic liquid crystals are prepared from racemic and optically active di-sodium N-lauroyl aspartate (SNLA). The optically active levo enantiomer is a suitable amphiphile for obtaining cholesteric lyotropic mesophases. In the present work, different types of mesophases, including cholesteric and nematic, were prepared and their type I or II magnetic behavior characterized by deuterium and 23Na NMR. The polarizing microscope textures were investigated, particularly with regards to magnetic field effects upon the samples. The usual chevron pattern was obtained for particular sample orientations and several characteristic effects were observed for the type I cholesteric lyomesophase in the first few minutes following removal of the sample from the magnetic field. Although the head group of di-sodium N-lauroyl aspartate possesses two negative charges, compositions are not too different from those reported for other amphiphile lyotropic systems. |
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Keywords: | deuterium relaxation spectral density angular dependence reorientation smectic |
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