Hydrophobic surfaces probed by atomic force microscopy
Hydrophobic surfaces probed by atomic force microscopy
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DOI：
10.1021/la0340450
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发表时间：
2003-06-24
期刊：
影响因子：
3.9
通讯作者：
de Souza, EF
中科院分区：
文献类型：
--
作者：
Teschke, O;de Souza, EF
我们已经测量了作用在中性针尖上的力作为到水溶液中疏水表面的距离的函数。这种力的异常大小归因于界面上的水流体结构(水化层)的静电响应。界面区域的局部电场是表面极性残基分布的一种表现，我们假设水中疏水表面的极化(水化)主要是由直接水结合驱动的。界面极化电荷与溶剂分子相应极化电荷之间的耦合最简单的静电描述在这里表示为空间可变的介电常数(INT)。具有介电常数的尖端(TIP)与界面区域的体积(INT)的交换是导致尖端吸引的原因。为了阐明长程引力的来源，测量了下列界面的可变介电常数分布：水/空气、水/CTAB覆盖的云母和水/疏水硅。
We have measured the force acting on neutral tips as a function of distance to hydrophobic surfaces in aqueous solutions. The unusually large magnitude of this force is attributed to the electrostatic response of the aqueous fluid structure (hydration layer) at the interface. The local electric field in an interfacial region is a manifestation of the distribution of surface polar residues, and we have assumed that the polarization (hydration) of the hydrophobic surface immersed in water is predominantly driven by the direct water binding. The simplest electrostatic description of the coupling between the interfacial polarization charges and the corresponding polarization charges of the solvent molecules is expressed here as the spatially variable dielectric permittivity epsilon(int). The exchange of a volume of the interfacial region with epsilon(int) by a tip with a dielectric constant epsilon(tip) is responsible for the tip attraction. The variable dielectric permittivity profiles for the following interfaces were measured in order to clarify the origin of the long-range attractive forces: water/air, water/CTAB covered mica, and water/hydrophobic silicon.