Physical and Theoretical Chemistry Laboratory, Oxford University, Oxford, United Kingdom.
J Colloid Interface Sci. 2011 Apr 15;356(2):656-64. doi: 10.1016/j.jcis.2011.01.024. Epub 2011 Jan 15.
The role of the polyelectrolyte, poly(ethyleneimine), PEI, and the electrolytes NaCl and CaCl(2), on the adsorption of the anionic surfactant, sodium dodecylbenzenesulfonate, LAS, at the air-water interface have been investigated by neutron reflectivity and surface tension. The surface tension data for the PEI/LAS mixtures are substantially affected by pH and the addition of electrolyte, and are consistent with a strong adsorption of surface polymer/surfactant complexes down to relatively low surfactant concentrations. The effects are most pronounced at high pH, and this is confirmed by the adsorption data obtained directly from neutron reflectivity. However, the effects of the addition of PEI and electrolyte on the LAS adsorption are not as pronounced as previously reported for PEI/SDS mixtures. This is attributed primarily to the steric hindrance of the LAS phenyl group resulting in a reduction in the ion-dipole attraction between the LAS sulfonate and amine groups that dominates the interaction at high pH.
通过中子反射率和表面张力研究了聚电解质聚乙烯亚胺（PEI）以及电解质 NaCl 和 CaCl2 对十二烷基苯磺酸钠（LAS）在气-液界面吸附的作用。PEI/LAS 混合物的表面张力数据受 pH 值和电解质添加的影响很大，并且与表面聚合物/表面活性剂复合物的强吸附一致，直至相对较低的表面活性剂浓度。在高 pH 值下，这些影响最为明显，这一点通过直接从中子反射率获得的吸附数据得到了证实。然而，PEI 和电解质对 LAS 吸附的影响不如以前报道的 PEI/SDS 混合物那么明显。这主要归因于 LAS 苯环的空间位阻，导致 LAS 磺酸盐和胺基之间的离子偶极吸引力降低，在高 pH 值下，这种吸引力占据主导地位。
