Origin of the long-range attraction between surfactant-coated surfaces
Origin of the long-range attraction between surfactant-coated surfaces
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DOI：
10.1073/pnas.0502110102
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发表时间：
2005-05-10
影响因子：
11.1
通讯作者：
Israelachvili, JN
中科院分区：
文献类型：
--
作者：
Meyer, EE;Lin, Q;Israelachvili, JN
我们比较了(i)在两个云母表面之间的“对称”系统中的“远程疏水力”，这两个云母表面通过吸附双链阳离子表面活性剂而变得疏水，(h)在一个这样的疏水表面和一个裸云母的亲水表面之间（“不对称”情况）。在这两种情况下，力都是纯粹的吸引力，比范德华力更强，而且像以前报道的那样是远距离的，而不对称的，疏水-亲水系统的力更强，范围更广。这些表面的原子力显微镜图像显示，当表面浸入水中时，单层转变成斑块状的双层，并且产生的表面包含大型微米大小的正电荷（双层）和负电荷（裸云母）区域，同时保持整体中性。当两个这样的表面接近时，相反带电域的自然排列将导致水中的远程静电吸引，但这些结果并不能解释短程的“真正疏水”相互作用。
We compare the "long-range hydrophobic forces" measured (i) in the "symmetric" system between two mica surfaces that had been rendered hydrophobic by the adsorption of a double-chained cationic surfactant, and (h) between one such hydrophobic surface and a hydrophilic surface of bare mica ("asymmetric" case). In both cases, the forces were purely attractive, stronger than van der Waals, and of long-range, as previously reported, with those of the asymmetric, hydrophobic-hydrophilic system being even stronger and of longer range. Atomic force microscopy images of these surfaces show that the monolayers transform into patchy bilayers when the surfaces are immersed in water, and that the resulting surfaces contain large micrometer-sized regions of positive charges (bilayer) and negative charges (bare mica) while remaining overall neutral. The natural alignment of oppositely charged domains as two such surfaces approach would result in a long-range electrostatic attraction in water, but the short-range, "truly hydrophobic" interaction is not explained by these results.