Wormlike Micelles Formed by Sodium Erucate in the Presence of a Tetraalkylammonium Hydrotrope

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• 作者：Yixiu Han ; Yujun Feng ; Huanquan Sun ; Zhenquan Li ; Yugui Han ; Hongyan Wang
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：June 2, 2011
• 年：2011
• 卷：115
• 期：21
• 页码：6893-6902
• 全文大小：1094K
• 年卷期：v.115,no.21(June 2, 2011)
• ISSN：1520-5207

文摘

Anionic wormlike micelles, particularly those formed by long-chain carboxylate surfactants, are relatively less documented though their cationic or zwitterionic counterparts are frequently reported. In this study, the wormlike micelles of sodium erucate (NaOEr), a C22-tailed anionic surfactant with a monounsaturated tail, in the presence of a tetraalkylammonium hydrotrope were investigated for the first time. The different effects of two hydrotropes, benzyl trimethyl ammonium bromide (BTAB) and tetramethyl ammonium bromide (TMAB), on the phase behavior and rheological behaviors were compared, and the influences of surfactant concentration and temperature on the rheological properties of NaOEr solutions were also examined. Both organic salts can lower the Krafft temperature of NaOEr solutions and thus improve its water solubility, but BTAB can make T_K drop more sharply. At a fixed NaOEr concentration, less BTAB is demanded to induce the formation of viscoelastic solution and to obtain the maximum viscosity of NaOEr solution; at a constant salt concentration, with increasing NaOEr content, the NaOEr鈥揃TAB system shows a larger zero-shear viscosity (畏₀), relaxation time, and plateau modulus but lower overlapping concentration than those of the NaOEr鈥揟MAB system. The occurrence of maximum 畏₀ with increasing salt content for the NaOEr鈥揃TAB system results from the formation of vesicles and L₃ phases, which were verified by cryo-TEM observations. 畏₀ shows an exponential decrease with increasing temperature; nevertheless it still remains above 10³ mPa路s even at 90 掳C.