Fegyver Edit, Mészáros Róbert
Laboratory of Interfaces and Nanosized Systems, Institute of Chemistry, Eötvös Loránd University , Pázmány Péter Sétány 1/A, Budapest 1117, Hungary.
Langmuir. 2014 Dec 23;30(50):15114-26. doi: 10.1021/la503928x. Epub 2014 Dec 12.
The various commercial applications of oppositely charged polyelectrolytes (P) and ionic surfactants (S) with added nonionic amphiphiles initiated intensive research on the polyion/mixed surfactant interaction. A large group of earlier studies revealed that one of the major effects of the nonionic cosurfactants is the suppression of the associative phase separation of P/S systems. In contrast, recent studies indicated that in the dilute surfactant concentration range the added uncharged amphiphile enhances the precipitation concentration range. In order to rationalize these observations, the mixtures of poly(diallyldimethylammonium chloride) (PDADMAC), sodium dodecyl sulfate (SDS), and dodecyl maltoside (C12G2) are investigated using a variety of experimental methods. It is shown that the nonionic cosurfactant has two distinct and competing impacts on the mixed surfactant binding onto the polyions. The composition dependent variation of the chemical potentials of the amphiphiles determines which of these effects is the dominant one, explaining the seemingly diverse earlier observations and their interpretations. We also demonstrate that the nonionic amphiphile affects considerably the nonequilibrium features of polyion/ionic surfactant complexation. Namely, the presence of the uncharged surfactant can destabilize the colloidal dispersion of P/S nanoparticles formed in the two-phase composition range. However, at the same concentration range highly stable dispersions of polyion/mixed surfactant nanoparticles can be produced through the application of a new two-step solution preparation technique. This method is based on the order of addition effect of the two surfactants which can be utilized in future scientific and industrial applications.
带相反电荷的聚电解质（P）和离子表面活性剂（S）与添加的非离子两亲物的各种商业应用引发了对聚离子/混合表面活性剂相互作用的深入研究。大量早期研究表明，非离子共表面活性剂的主要作用之一是抑制P/S体系的缔合相分离。相比之下，最近的研究表明，在稀表面活性剂浓度范围内，添加的不带电荷的两亲物会提高沉淀浓度范围。为了合理解释这些观察结果，使用多种实验方法研究了聚二烯丙基二甲基氯化铵（PDADMAC）、十二烷基硫酸钠（SDS）和十二烷基麦芽糖苷（C12G2）的混合物。结果表明，非离子共表面活性剂对混合表面活性剂与聚离子的结合有两种不同且相互竞争的影响。两亲物化学势随组成的变化决定了哪种影响占主导地位，这解释了早期看似多样的观察结果及其解释。我们还证明，非离子两亲物对聚离子/离子表面活性剂络合的非平衡特征有相当大的影响。也就是说，不带电荷的表面活性剂的存在会使在两相组成范围内形成的P/S纳米颗粒的胶体分散体不稳定。然而，在相同浓度范围内，可以通过应用一种新的两步溶液制备技术来制备聚离子/混合表面活性剂纳米颗粒的高度稳定分散体。该方法基于两种表面活性剂的添加顺序效应，可用于未来的科学和工业应用。
