NDLI: Phase behavior and properties of salt-free cationic/anionic surfactant mixtures of oleic acid and stearic acid

Content Provider	Springer Nature Link
Author	Zhao, DianYing Li, HongGuang Song, AiXin Hao, JingCheng
Copyright Year	2009
Abstract	Cationic base surfactant, tetradecyltrimethylammonium hydroxide (TTAOH), can be obtained through anion exchange from tetradecyltrimethylammonium bromide (TTABr). Salt-free cationic and anionic (catanionic) surfactant mixtures were studied by mixing TTAOH with oleic acid (OA) or stearic acid (SA) in water. The phase behavior of TTAOH/OA/H$_{2}$O is compared with that of TTAOH/SA/H$_{2}$O. It was found that the phase behavior of TTAOH/OA/H$_{2}$O and TTAOH/SA/H$_{2}$O system differs from each other due to the existence of the unsaturated double carbon bond (C=C) in OA. At fixed total surfactant concentration (25 mg/mL) of TTAOH/OA/H$_{2}$O system at 25°C, one can observe an isotropic L$_{1}$ phase, and a L$_{1}$/L$_{α}$ two-phase region with increasing OA content. The volume of top turbid L$_{α}$ phase increases while the bottom phase changes gradually from transparently clear to a bit turbid until a single L$_{α}$-phase is reached. Finally at high OA concentration, excess OA is separated from the bulk aqueous solutions. TTAOH/SA/H$_{2}$O system usually forms white precipitating at 25°C due to the high chain melting temperature of SA. When heated to 60°C, however, the state of samples changes. At fixed total surfactant concentration of 25 mg/mL, an isotropic L$_{1}$ phase and a milk-white or bluish L$_{α}$-phase are observed with increasing SA concentration. Transparent thin layers which are strongly birefringent form at the tops of some samples within the L$_{α}$-phase region. Finally, at high SA concentration, excess SA is separated from the bulk aqueous solutions. In addition to phase behavior study, we also measured the conductivity of TTAOH/OA/H$_{2}$O system at 25°C and TTAOH/SA/H$_{2}$O system at 60°C, respectively. Surface tension and rheological measurements were also performed on typical samples.
Starting Page	3953
Ending Page	3957
Page Count	5
File Format	PDF
ISSN	10016538
Journal	Chinese Science Bulletin
Volume Number	54
Issue Number	21
e-ISSN	18619541
Language	English
Publisher	SP Science in China Press
Publisher Date	2009-11-25
Publisher Place	Heidelberg
Access Restriction	Subscribed
Subject Keyword	salt-free cationic/anionic surfactant solution phase behavior L$_{α}$-phase rheological properties Engineering Earth Sciences Chemistry/Food Science Physics Life Sciences Science
Content Type	Text
Resource Type	Article
Subject	Multidisciplinary

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