The Behavior of Sorbitan Surfactants at the Water-Oil Interface: Straight-Chained Hydrocarbons from Pentane to Dodecane as an Oil Phase.
The Behavior of Sorbitan Surfactants at the Water-Oil Interface: Straight-Chained Hydrocarbons from Pentane to Dodecane as an Oil Phase.
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DOI：
10.1006/jcis.2001.7612
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发表时间：
2001-08
影响因子：
9.9
通讯作者：
L. Peltonen;J. Hirvonen;J. Yliruusi
中科院分区：
文献类型：
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作者：
L. Peltonen;J. Hirvonen;J. Yliruusi
测定了四种山梨醇表面活性剂(Span 20、Span 40、Span 60、Span 80)在油水界面上的界面张力。从正戊烷到正十二烷的7种直链碳氢化合物被用作油相。根据界面张力的测量，计算出以下数值：临界胶束浓度(CMC)、CMC处的界面张力(γ(CMC))、CMC处的表面压力(pi(CMC))、CMC处的每个分子的面积(A(CMC))、标准胶束化自由能(DeltaG度(Mic))和标准吸附自由能(DeltaG度(Ad))。链长较短的Span 20和不饱和Span 80的CMC值较高，Span 80的分子面积较大。在相同油相下，四种山梨醇单酯的pi(Cmc)值相差不大，但随着表面活性剂疏水性的增加，pi(Cmc)略有降低。Span 20的DeltaG度(MIC)负值较小，Span 80的DeltaG度(Ad)值略负。油相的作用效果明显。随着油相碳氢链长的增加，伽马(CMC)和CMC值增大，pi(CMC)和A(CMC)减小。随着油相碳氢链长度的增加，DeltaG度(Mic)和DeltaG度(Ad)变得较小，这意味着自发反应较少。学术出版社版权所有2001年。
The interfacial tension of four sorbitan surfactants (Span 20, sorbitan monolaurate; Span 40, sorbitan monopalmitate; Span 60, sorbitan monostearate; and Span 80, sorbitan monooleate) was determined at the water-oil interface. Seven straight-chained hydrocarbons from pentane to dodecane were used as an oil phase. From the interfacial tension measurements the following values were calculated: critical micelle concentration (cmc), the interfacial tension at the cmc (gamma(cmc)), surface pressure at the cmc (pi(cmc)), area per molecule at the cmc (A(cmc)), standard free energy of micellization (DeltaG degrees (mic)), and standard free energy of adsorption (DeltaG degrees (ad)). The shorter chained Span 20 and unsaturated Span 80 had higher cmc values and Span 80 had a larger molecular area than the other surfactants. With the same oil phase, differences between pi(cmc) values of the four sorbitan monoesters were small, but the gamma(cmc) was slightly lowered as the hydrophobicity of the surfactant was increased. DeltaG degrees (mic) was less negative for Span 20 and the DeltaG degrees (ad) value was slightly more negative for Span 80. The effect of the oil phase was obvious. Increasing the hydrocarbon chain length of the oil phase increased gamma(cmc) and cmc values while pi(cmc) and A(cmc) were decreased. As the length of the hydrocarbon chain of the oil phase was increased, DeltaG degrees (mic) and DeltaG degrees (ad) became less negative, which means a less spontaneous reaction. Copyright 2001 Academic Press.