Varga Imre, Mészaros Róbert, Gilanyi Tibor
Laboratory of Interfaces and Nanosize Systems, Institute of Chemistry, Eötvös LorAnd University, Budapest, Hungary.
J Phys Chem B. 2007 Jun 28;111(25):7160-8. doi: 10.1021/jp071344f. Epub 2007 May 27.
Experimental results are presented on the adsorption of sodium alkyl sulfate homologues (nC = 8-14) at the air/solution interface. The adsorption isotherms calculated from equilibrium surface-tension vs concentration data and the critical micelle concentration change regularly with the length of the alkyl chain; the odd/even effect was not observed. The isotherms were analyzed using a model-independent approach. The analysis indicates that the total driving force of adsorption reaches a plateau value and becomes constant in the function of the adsorbed amount in the case of each homologue. With the use of different electrostatic models, it was demonstrated that this behavior is consistent with a saturation-type hydrophobic driving-force contribution, which can be interpreted by the development of a liquidlike alkane environment in the adsorbed layer above a "critical" adsorbed amount.
本文展示了关于烷基硫酸钠同系物（nC = 8 - 14）在空气/溶液界面吸附的实验结果。根据平衡表面张力与浓度数据计算得到的吸附等温线以及临界胶束浓度随烷基链长度有规律地变化；未观察到奇偶效应。采用与模型无关的方法对等温线进行了分析。分析表明，对于每种同系物，吸附的总驱动力达到一个平台值，并在吸附量的函数关系中保持恒定。通过使用不同的静电模型，证明了这种行为与饱和型疏水驱动力贡献一致，这可以通过在“临界”吸附量以上的吸附层中形成类液态烷烃环境来解释。
