Adsorption layer properties of alkyltrimethylammonium bromides at interfaces between water and different alkanes

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• 作者：N. Mucic ; N.M. Kovalchuk ; E.V. Aksenenko ; V.B. Fainerman ; R. Miller
• 关键词：Cationic surfactants ; Adsorption isotherms ; Water&ndash ; alkane interface ; Chain length dependence ; Interfacial tension ; Drop profile analysis tensiometry
• 刊名：Journal of Colloid and Interface Science
• 出版年：2013
• 出版时间：15 November, 2013
• 年：2013
• 卷：410
• 期：Complete
• 页码：181-187
• 全文大小：1189 K

文摘

We measured the interfacial tensions of aqueous solutions against different oil phases using drop profile analysis tensiometry (PAT-1, Sinterface Technologies, Germany) for decyl- and dodecyltrimethylammonium bromide (C₁₀TAB and C₁₂TAB) in phosphate buffer (10 mM, pH7). The following alkanes were used as oil phases: hexane, heptane, octane, nonane, decane, dodecane and tetradecane. The obtained equilibrium interfacial tension isotherms were fitted by the Frumkin Ionic Compressibility model (FIC). The surfactants adsorb at the water/oil interface in competition with the oil molecules. At high surfactant surface coverage this competitive adsorption is manifested in two ways. First, for short chain surfactants, the oil molecules are embedded into the adsorption layer. Second, for long chain surfactants, the short alkane chains of the oil molecules are squeezed out from the adsorption layer due to strong mutual interaction between surfactants¡¯ chains.