Behavior of 10-(perfluorohexyl)-decanol, a partially fluorinated analog of hexadecanol, at the air–water interface

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• 作者：Lehmler ; Hans-Joachim ; Bummer ; Paul M.
• 关键词：Langmuir isotherms ; DSC ; Fluorinated ; Hexadecanol
• 刊名：Journal of Fluorine Chemistry
• 出版年：2002
• 出版时间：September 28, 2002
• 年：2002
• 卷：117
• 期：1
• 页码：17-22
• 全文大小：129 K

文摘

10-(Perfluorohexyl)-decanol is a partially fluorinated analog of hexadecanol, an important detergent alcohol. With a melting point of T=48.82°C and a melting enthalpy of ΔH=53.96J/g, the intermolecular interactions of the fluorinated alcohol are weaker compared to hexadecanol (T=52.67°C, ΔH=244.41J/g). The behavior of this fluorinated alcohol at the air–water interface was studied on five different subphases, namely, water, NaCl (150mM), CaCl₂ (2mM), HCl (pH=2.0), and urea (0.5M). Similar to other partially fluorinated amphiphiles, the compression isotherms of the fluorinated alcohol on all subphases are more expanded compared to the hydrocarbon alcohol with a limiting area of 32–36Ų per molecule and a temperature-dependent phase transition at 5.6–8.2mN/m (37°C, compression rate of 10mm/min). The dependence of the compression isotherms of 10-(perfluorohexyl)-decanol on subphase composition and temperature follows the trends reported for tetra- and hexadecanol. In particular, a shift to smaller molecular areas with increasing temperatures was observed on all five subphases. The shift to smaller molecular areas on urea indicates that in the case of 10-(perfluorohexyl)-decanol the effect is largely due to a loss of material from the air–water interface during compression of the monolayers. However, a squeezing-out of water molecules from the hydration sphere of the polar headgroup may still occur but can not be unambiguously proven.