Department of Chemical Engineering, University of Washington , Box 351750, Seattle, Washington 98195-1750, United States.
Langmuir. 2016 Oct 11;32(40):10328-10333. doi: 10.1021/acs.langmuir.6b02959. Epub 2016 Sep 28.
This paper investigates the effects of reverse micellar core size on the particle charging behavior of a series of acidic surfactants in apolar media. A series of Span surfactants was dissolved in deuterated decane at concentrations above the critical micelle concentration. The structures of the reverse micelles were measured using small-angle neutron scattering. It was determined that as the tail length of the surfactant increased, the size of the polar reverse micellar core decreased. Tritailed surfactants formed reverse micelles with the smallest polar cores, with radii of ∼4 Å. The sizes of the polar cores were correlated with the particle charging behavior of the Span surfactant series, as measured in a previous study. It was found that reverse micelles with intermediate core sizes imparted the largest electrophoretic mobilities to the particles. Reverse micelles with very small cores did not offer a large enough polar environment to favor charge stabilization, while very large polar cores favored disproportionation reactions in the bulk, resulting in increased electrostatic screening.
本文研究了反胶束核大小对一系列在非极性介质中带酸性基团的表面活性剂颗粒荷电行为的影响。一系列 Span 表面活性剂在高于临界胶束浓度的浓度下溶解在氘代癸烷中。使用小角中子散射测量了反胶束的结构。结果表明，随着表面活性剂的尾链长度增加，极性反胶束核的尺寸减小。三尾表面活性剂形成的反胶束具有最小的极性核，半径约为 4 Å。极性核的大小与之前研究中测量的 Span 表面活性剂系列的颗粒荷电行为相关。结果发现，具有中等核大小的反胶束赋予颗粒最大的电泳迁移率。具有非常小核的反胶束不能提供足够大的极性环境来有利于电荷稳定，而非常大的极性核有利于在本体中发生歧化反应，导致静电屏蔽增加。
