Centre for Organic Electronics, The University of Newcastle, Callaghan, NSW 2308, Australia.
Langmuir. 2010 Jun 1;26(11):8313-8. doi: 10.1021/la9047243.
The adsorbed layers of polyoxyethylene n-alkyl ether surfactants C(12)E(4), C(14)E(4), and C(16)E(4) at the EAN surface have a headgroup layer that is thin and compact (only approximately 30 vol % EAN). The headgroups do not adopt a preferred orientation and are disordered within the ethylene oxide layer. Alkyl tails contain a significant number of gauche defects indicating a high degree of conformational disorder. The thickness of the tail layer increases with increasing alkyl chain length, while the headgroup layer shows little change. Lowering the C(12)E(4) concentration from 1 to 0.1 wt % decreases the adsorbed amount, and the headgroup layer becomes thinner and less solvated, whereas C(14)E(4) and C(16)E(4) adsorbed layers are unaffected by dilution over the same concentration range. The C(16)E(4) layer thickness increases and area per molecule decreases on warming to 60 degrees C, but the adsorbed layer structures of C(12)E(4) and C(14)E(4) are unchanged. Both effects are attributed to surfactant solubility.
聚氧乙烯正烷基醚表面活性剂 C(12)E(4)、C(14)E(4) 和 C(16)E(4) 在 EAN 表面的吸附层具有薄而紧凑的头部层（仅约 30 体积% EAN）。头部基团没有采用优先取向，并且在氧化乙烯层内无序。烷基尾包含大量的 gauche 缺陷，表明构象无序程度很高。随着烷基链长度的增加，尾层的厚度增加，而头部层几乎没有变化。将 C(12)E(4)浓度从 1 降至 0.1wt%会降低吸附量，头部层变得更薄且溶剂化程度更低，而 C(14)E(4)和 C(16)E(4)吸附层在相同浓度范围内稀释时不受影响。在升温至 60°C 时，C(16)E(4)层厚度增加且每个分子的面积减小，但 C(12)E(4)和 C(14)E(4)的吸附层结构不变。这两种效应都归因于表面活性剂的溶解度。
