Temperature- and pH-Dependent Shattering: Insoluble Fatty Ammonium Phosphate Films at Water-Oil Interfaces.
Temperature- and pH-Dependent Shattering: Insoluble Fatty Ammonium Phosphate Films at Water-Oil Interfaces.
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DOI：
10.1021/acs.langmuir.5b01981
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发表时间：
2015-08
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影响因子：
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通讯作者：
J. Forth;David J. French;A. Gromov;S. King;S. Titmuss;K. M. Lord;M. Ridout;P. Wilde;P. Clegg
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文献类型：
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作者：
J. Forth;David J. French;A. Gromov;S. King;S. Titmuss;K. M. Lord;M. Ridout;P. Wilde;P. Clegg
研究了磷酸氢根离子存在下十四胺（TDA）在水-十二烷界面上形成的膜。利用傅里叶变换红外光谱（FTIR）、界面剪切流变学、共聚焦荧光显微镜、低温扫描电子显微镜（cryo-SEM）和小角中子散射（SANS），我们发现在pH 5和8之间，十四烷基铵阳离子与磷酸氢根结合。阴离子形成十四烷基磷酸氢铵（TAHP）的针状微晶。这些微晶自组装成具有一系列形态的膜;在pH 7以下，它们形成脆性的连续片，在pH 8下，它们形成在剪切下塑性变形的花边状网络。它们也对温度敏感：当系统被加热时，薄膜变薄，流变模量下降。我们发现，温度响应是由溶解的膜在体相流体相。最后，我们表明，这些膜可用于稳定温度响应性的油包水乳液，在活性分子的控制释放中具有潜在的应用。
We study the films formed by tetradecylamine (TDA) at the water-dodecane interface in the presence of hydrogen phosphate ions. Using Fourier transform infrared spectroscopy (FTIR), interfacial shear rheology, confocal fluorescence microscopy, cryo-scanning electron microscopy (cryo-SEM), and small-angle neutron scattering (SANS), we find that between pH 5 and 8 tetradecylammonium cations bind to hydrogen phosphate anions to form needle-shaped crystallites of tetradecylammonium hydrogen phosphate (TAHP). These crystallites self-assemble into films with a range of morphologies; below pH 7, they form brittle, continuous sheets, and at pH 8, they form lace-like networks that deform plastically under shear. They are also temperature-responsive: when the system is heated, the film thins and its rheological moduli drop. We find that the temperature response is caused by dissolution of the film in to the bulk fluid phases. Finally, we show that these films can be used to stabilize temperature-responsive water-in-oil emulsions with potential applications in controlled release of active molecules.