物理化学学报 >> 1986, Vol. 2 >> Issue (04): 297-301.doi: 10.3866/PKU.WHXB19860406

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聚醚型表面活性剂在界面上的分子取向
Ⅰ. Triton X-100和Triton X-305在水面上的展开膜

李外郎; 潘传斌; 顾惕人   

  1. 北京大学物理化学研究所
  • 收稿日期:1985-07-06 修回日期:1986-02-26 发布日期:1986-08-15

THE MOLECULAR ORIENTATION OF POLYETHER-TYPE SURFACTANTS AT THE INTERFACES
Ⅰ. THE SURFACE FILMS OF TRITON X-100 AND TRITON X-305

Li Wailang; Pan Chuanbin; Gu Tiren   

  1. Institute of Physical Chemistry, Peking University
  • Received:1985-07-06 Revised:1986-02-26 Published:1986-08-15

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摘要： 研究了25 ℃时Triton X-100和Triton X-305在46.6％NaNO_3水溶液/空气界面上的展开膜。根据表面压、分子面积和分子中乙氧基数目三者之间的关系, 提出了一种界面分子模型。简言之, 分子的烷烃链伸进气相或油相, 分子中间的苯环平躺于界面, 而分子的乙氧基链则以一部分链节平躺于界面、其余的链节伸进水相的方式取向。平躺于界面的乙氧基链节的比例随表面压的增加而减小。这个模型不仅可以合理地解释已知的实验事实, 而且可能适用于包括空气/水和油/水界面上的展开膜和吸附膜。

Abstract: The film pressure vs. area curves of the surface films of Triton X-100 and Triton X-305 have been determined on a 46.6% NANO_3 substrates at 25 ℃. The results suggest that the area per molecule on the surface at constant film pressure is a linear function of ethylene oxide chain length. It is proposed that the amphipathic molecule orients at the air/water interface with the hydrophobic group above the interface and the ethylene oxide chain partly lies in the interface and partly penetrates the water phase. Although the fraction of the number of ethylene oxide unit lain in the interface, f, increase progressively with film pressure, is independent of n, the ethylene oxide chain length. With this model, the experimental results can be explained.