Department of Physics and Astronomy, Uppsala University, Box 516, 751 20, Uppsala, Sweden.
Langmuir. 2010 Sep 21;26(18):14567-73. doi: 10.1021/la101969p.
Aerosol-OT (sodium bis 2-ethylhexyl sulfosuccinate or NaAOT) adsorbs to hydrophilic sapphire solid surfaces. The structure of the formed bilayer has been determined over the concentration range 0.2-7.4 mM NaAOT. It was found that the hydrocarbon tails pack at maximum packing limit at very low concentrations, and that the thickness of the bilayer was concentration-independent. The adsorption was found to increase with concentration, with the surfactant molecules packing closer laterally. The area per molecule was found to change from 138 ± 25 to 51 ± 4 A(2) over the concentration range studied, with the thickness of the layer being constant at 33 ± 2 A. Addition of small amounts of salt was found to increase the surface excess, with the bilayer being thinner with a slightly larger area per molecule. Addition of different salts of the same valency was found to have a very similar effect, as had the addition of NaOH and HCl. Hence, the effects of adding acid or base should be considered an effect of ionic strength rather than an effect of pH. Adsorption of NaAOT to the sapphire surface that carries an opposite charge to the anionic surfactant is similar in many respects to the adsorption reported previously for hydrophilic and hydrophobic silica surfaces. This suggests that the adsorption of NaAOT to a surface is driven primarily by NaAOT self-assembly rather than effects of electrostatic attraction to the interface.
气溶胶-OT（双 2-乙基己基磺基琥珀酸钠或 NaAOT）吸附在亲水蓝宝石固体表面上。在 0.2-7.4mM NaAOT 的浓度范围内，已经确定了形成的双层结构。结果发现，在非常低的浓度下，烃尾达到最大堆积限度，并且双层的厚度与浓度无关。发现吸附随浓度增加而增加，表面活性剂分子横向排列更紧密。发现每个分子的面积从 138±25 变为 51±4A2，在研究的浓度范围内，层的厚度保持在 33±2A。添加少量盐被发现会增加表面过剩，双层更薄，每个分子的面积略大。添加相同价态的不同盐具有非常相似的效果，添加 NaOH 和 HCl 也是如此。因此，添加酸或碱的效果应被视为离子强度的影响，而不是 pH 值的影响。带相反电荷的阴离子表面活性剂 NaAOT 对蓝宝石表面的吸附在许多方面与先前报道的亲水和疏水二氧化硅表面的吸附相似。这表明 NaAOT 对表面的吸附主要是由 NaAOT 自组装驱动的，而不是界面静电吸引的影响。
