Interfacial water on hydrophobic surfaces recognized by ions and molecules.
Interfacial water on hydrophobic surfaces recognized by ions and molecules.
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DOI：
10.1039/c1cp20704k
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发表时间：
2011-08
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最近的分光光度和分子动力学模拟研究表明，在疏水表面附近的水的物理化学性质和结构不同于散装水。然而，作为疏水表面上的分离介质的界面水从来没有被检测到和量化的实验。在这项研究中，我们表明，小的无机离子和有机分子区分十八烷基键合的（C（18））二氧化硅颗粒表面上形成的界面水从本体水和这些溶质在水介质中与疏水材料的化学分离可以解释与一致的机制，本体水相和疏水表面上形成的界面水之间的分区。结合在C（18）二氧化硅材料的纳米孔中的界面水的热转变行为和由有机化合物的分配系数计算的水的溶解度参数已经表明界面水可能具有破坏的氢键结构。根据液相色谱法测得的界面水体积和表面积，估算出界面水的厚度或分子和离子能感知到表面的距离极限为1.25 ± 0.13 nm，表明疏水效应可能延伸到直接包围表面的水分子的第一溶剂化壳层之外。
Recent spectrophotometric and molecular dynamics simulation studies have shown that the physicochemical properties and structures of water in the vicinity of hydrophobic surfaces differ from those of the bulk water. However, the interfacial water acting as a separation medium on hydrophobic surfaces has never been detected and quantified experimentally. In this study, we show that small inorganic ions and organic molecules differentiate the interfacial water formed on the surfaces of octadecyl-bonded (C(18)) silica particles from the bulk water and the chemical separation of these solutes in aqueous media with hydrophobic materials can be interpreted with a consistent mechanism, partition between the bulk water phase and the interfacial water formed on the hydrophobic surface. Thermal transition behaviour of the interfacial water incorporated in the nanopores of the C(18) silica materials and the solubility parameter of the water calculated from the distribution coefficients of organic compounds have indicated that the interfacial water may have a structure of disrupted hydrogen bonding. The thickness of the interfacial water or the limit of distance from the hydrophobic surface at which molecules and ions can sense the surface was estimated to be 1.25 ± 0.13 nm from the volume of the interfacial water obtained by a liquid chromatographic method and the surface area, suggesting that the hydrophobic effect may extend beyond the first solvation shell of water molecules directly surrounding the surfaces.