Thormann Esben, Simonsen Adam C, Hansen Per L, Mouritsen Ole G
MEMPHYS, Department of Physics and Chemistry, University of Southern Denmark, Campusvej 55, DK-5230 Odense M, Denmark.
ACS Nano. 2008 Sep 23;2(9):1817-24. doi: 10.1021/nn800218s.
An atomic force microscope and the colloidal probe technique are used to probe the interaction between a hydrophobic particle and a hydrophobic surface in water. The characteristics of the observed force curves strongly suggest that a gas bubble is formed when the particle is moved toward the surface and that the bubble ruptures when the particle subsequently is retracted from the surface. We demonstrate that this type of interaction is not unique for hydrophobic surfaces in water since the interaction between hydrophilic surfaces in air provides very similar force curves. However, the interaction between hydrophobic surfaces vanish if water is replaced by an organic solvent with low polarity. The bridging bubble model is employed to explain the hysteresis observed between approach and retraction force traces and experimental conditions where the hysteresis can be almost eliminated are identified. Finally, it is demonstrated that the hydrophobic interaction is strongly temperature dependent and this dependence can be attributed mainly to the decreasing solubility of air in water with increasing temperature.
使用原子力显微镜和胶体探针技术来探测水中疏水颗粒与疏水表面之间的相互作用。观察到的力曲线特征强烈表明，当颗粒向表面移动时会形成气泡，而当颗粒随后从表面缩回时气泡会破裂。我们证明这种相互作用并非水中疏水表面所特有，因为空气中亲水表面之间的相互作用提供了非常相似的力曲线。然而，如果用水被低极性有机溶剂取代，疏水表面之间的相互作用就会消失。采用桥连气泡模型来解释在接近和缩回力曲线之间观察到的滞后现象，并确定了几乎可以消除滞后现象的实验条件。最后，证明了疏水相互作用强烈依赖于温度，这种依赖性主要可归因于随着温度升高空气中的溶解度降低。
