Discotic Nematic – Calamitic Nematic Phase Transition in Sodium Dodecyl (lauryl) Sulphate – Decanol – D₂O

Abstract

The optical characterization of uniaxial nematic liquid crystals gives basic information on its birefringence and on the shape anisotropy of micelles in nematic lyotropic phases. In this work, these optical parameters were determined as a function of temperature along the sequence discotic nematic (N _D ) – coexistence (N_D + N_C) – calamitic nematic (N _C ) – isotropic (I) in a lyotropic mixture of the sodium dodecyl (lauryl) sulphate (SDS) – decanol (D _e OH) and D ₂ O for a specific concentration. Results for the uniaxial phases agree with previous assignments. Results in the coexistence region indicate an inhomogeneous mixture of the two uniaxial phases.

Keywords:

• Lyotropic uniaxial nematic phases
• phase coexistence
• refractive index

Acknowledgment

We are thankful to the Brazilian Agencies CAPES, Fundação Araucária (PR), and to INCT of Complex Fluids (CNPq/MCT/FAPESP) for the financial support.