Acta Phys. -Chim. Sin. ›› 2002, Vol. 18 ›› Issue (10): 920-923.doi: 10.3866/PKU.WHXB20021011

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Phase Behavior of Mixed Aqueous Solution of Octyltrimethylamonium Bromide and Sodium Octyl Sulfate

Hu Shang-Lin;Jia Xiao-Fei;Dai Le-Rong   

  1. College of Chemistry and Molecular Engineering, Peking University, Beijing 100871
  • Received:2002-02-07 Revised:2002-03-26 Published:2002-10-15
  • Contact: Dai Le-Rong

Abstract: The phase behavior of aqueous mixture of octyltrimethylamonium bromide (OTAB) and sodium octyl sulfate (SOS)was studied. In concentrated solution, a liquid crystal phase formed and converted form hexangonal structure to lamellar when the molar ratio of OTAB/SOS approached to 1.The mixed surfactant solution is a homogeneous and transparent liquid in middle concentration range. When the concentration is low, aqueous two-phase system appears in a wide range of OTAB/SOS molar ratio. In the aqueous surfactant two phase system, both vesicles and micelles exist in the surfactant-poor phase, while concentrated vesicle aggregates were contained in the surfactant-rich phase. Solubilization amount of oil-soluble dye in the surfactant-rich phase is much higher than that in the surfactant-poor phase.

Key words: Mixed cationic-anionic surfactant, Phase behavior, Liquid crystal,  Aqueous two phase, Vesicles