School of Science, State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Qingdao 266580, China; ISIS Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK.
ISIS Facility, Rutherford Appleton Laboratory, STFC, Chilton, Didcot, Oxon OX11 0QX, UK.
J Colloid Interface Sci. 2021 Mar 15;586:876-890. doi: 10.1016/j.jcis.2020.10.122. Epub 2020 Nov 5.
The α-sulfo alkyl ester, AES, surfactants are a class of anionic surfactants which have potential for improved sustainable performance in a range of applications, and an important feature is their enhanced tolerance to precipitation in the presence of multivalent counterions. It is proposed that their adsorption properties can be adjusted substantially by changing the length of the shorter alkyl chain, that of the alkanol group in the ester.
Surface tension and neutron reflectivity have been used to investigate the variation in the adsorption properties with the shorter alkyl chain length (methyl, ethyl and propyl), the impact of NaCl on the adsorption, the tendency to form surface multilayer structures in the presence of AlCl, and the effects of mixing the methyl ester sulfonate with the ethyl and propyl ester sulfonates on the adsorption.
The variations in the critical micelle concentration, CMC, the adsorption isotherms, the saturation adsorption values, and the impact of NaCl illustrate the subtle influence of varying the shorter alkyl chain length of the surfactant. The non-ideal mixing of pairs of AES surfactants with different alkanol group lengths of the ester show that the extent of the non-ideality changes as the difference in the alkanol length increases. The surface multilayer formation observed in the presence of AlCl varies in a complex manner with the length of the short chain and for mixtures of surfactants with different chains lengths.
α-磺基烷基酯（AES）表面活性剂是一类阴离子表面活性剂，在一系列应用中具有提高可持续性能的潜力，其一个重要特点是在多价抗衡离子存在下提高了抗沉淀能力。据推测，通过改变酯中较短的烷基链和烷醇基团的长度，可以大大调节其吸附性能。
利用表面张力和中子反射率研究了吸附性能随较短烷基链长度（甲基、乙基和丙基）的变化、NaCl 对吸附的影响、在存在 AlCl 时形成表面多层结构的趋势，以及混合甲酯磺酸盐与乙和丙酯磺酸盐对吸附的影响。
临界胶束浓度（CMC）、吸附等温线、饱和吸附值的变化以及 NaCl 的影响说明了改变表面活性剂较短烷基链长度的细微影响。具有不同酯烷醇基团长度的 AES 表面活性剂对的非理想混合表明，非理想性的程度随着烷醇长度差的增加而变化。在存在 AlCl 的情况下观察到的表面多层形成以复杂的方式随短链长度而变化，并且对于具有不同链长的表面活性剂混合物也是如此。
