Abstract

The concentration-dependent physicochemical behaviors of the binary mixtures of polyalkoxylated fatty alcohol (PAFA)-AS (alkyl sulfonate), PAFA-CB (cocamidopropyl betaine) and PAFA-APG (alkyl polyglucosides) and their micellar interactions were determined at the ratios of 9:1, 8:2, 7:3 and 6:4 (w/w). At concentrated level, the rheological study of all the PAFA-mixed surfactants display a Newtonian behavior at low viscosities. Prominent discrepancies among the mixed surfactant systems were observed after stepwise dilution of the samples. In tensiometry study, the types of mutual interaction in the mixed surfactant systems were evaluated by regular solution theory (RST). The CMC_exp curves of PAFA-AS and PAFA-CB systems demonstrate lower position than their CMC_theo curves signifying that these nonionic–anionic and nonionic–zwitterionic samples behave nonideal showing synergistic interaction between individual components in the mixed micelles, as further verified by the negative values of interaction parameter β and activity coefficients f₁ and f₂ are less than 1. Meanwhile, the PAFA-APG system shows no significant mutual interaction between the nonionic–nonionic components in the mixed micelles. TEM micrographs depict the formations of branched wormlike micelles and multiconnected threadlike networks for the PAFA-AS and PAFA-CB systems, respectively, while gigantic multilamellar vesicles for the PAFA-APG system. Upon dilution of these mixed surfactants to CMC, the mixed micelles are in monodisperse sizes of less than 15 nm and in various magnitudes of zeta potential ranging from –2.92 to –21.87 mV.

摘要

在比例为 9 :1, 8:2, 7:3 和 6:4 (w/w)。在浓缩水平下，所有 PAFA 混合表面活性剂的流变学研究显示出低粘度下的牛顿行为。在逐步稀释样品后，观察到混合表面活性剂体系之间的显着差异。在张力学研究中，混合表面活性剂体系中相互作用的类型通过规则溶液理论（RST）进行评估。PAFA-AS 和 PAFA-CB 系统的 CMC _exp曲线表明位置低于其 CMC _theo曲线表明这些非离子 - 阴离子和非离子 - 两性离子样品表现出不理想的表现，显示混合胶束中各个组分之间的协同相互作用，正如相互作用参数 β 和活性系数f ₁和f ₂的负值所进一步证实的小于 1。同时，PAFA-APG 系统显示混合胶束中非离子-非离子组分之间没有显着的相互作用。TEM 显微照片分别描绘了 PAFA-AS 和 PAFA-CB 系统的分支蠕虫状胶束和多连接线状网络的形成，而 PAFA-APG 系统则描绘了巨大的多层囊泡。将这些混合表面活性剂稀释为 CMC 后，混合胶束的单分散尺寸小于 15 nm，zeta 电位的大小范围从 –2.92 到 –21.87 mV。