Structure of Partially Fluorinated Surfactant Monolayers at the Air−Water Interface†

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• 作者：A. J. Jackson*^‡ ; ; P. X. Li^‡ ; ; C. C. Dong^‡ ; ; R. K. Thomas^‡ ; ; J. Penfold^§ ;
• 刊名：Langmuir
• 出版年：2009
• 出版时间：April 7, 2009
• 年：2009
• 卷：25
• 期：7
• 页码：3957-3965
• 全文大小：258K
• 年卷期：v.25,no.7(April 7, 2009)
• ISSN：1520-5827

文摘

Partially fluorinated cationic surfactants of the form C_nF_2n+1C_mH_2mN(CH₃)Br have been prepared, and their behavior at the air−water interface has been studied using surface tension measurements and neutron reflectometry. The degree of fluorination has been varied while keeping the overall chain lengths similar. The results are compared with those previously obtained for C₁₆H₃₃N(CH₃)Br (C16TAB). The structural studies show a decrease in molecular orientation with increasing fluorination. The mean tilt away from the surface normal varies from 55° for C16TAB to 25° for C₈F₁₇C₆H₁₂N(CH₃)Br. The interfacial layer roughness is observed to be lower than that expected for a pure fluorocarbon surfactant.