Hypothesis

Shear-thickening micelles were mostly made of cationic surfactants, but shear-thickening was rarely reported in the zwitterionic/anionic surfactants. Since wormlike micelles were essential in shear-thickening systems, it should be common for the hybrid wormlike micelles formed by zwitterionic/anionic surfactants, and their fundamental features need to be clarified.

Experiments

The micellization of zwitterionic surfactant homologies alkyl dimethyl amidopropyl hydroxyl sulfobetaine (AHSB) and sodium dodecyl sulfate (SDS) in brine was studied, and various environmental factors were considered systematically. Light scattering, rheology, zeta potential, ¹H NMR and cryo-TEM techniques were employed to characterize the AHSB/SDS wormlike micelles.

Findings

AHSB/SDS hybrid wormlike micelles were formed in a wide x_SDS region to endow them with apparent viscosities, in which the electrostatic and hydrophobic interactions between AHSB and SDS molecules were critical. AHSB with the longer tail, the higher c_AHSB and c_NaCl were advantageous to enhance the viscosity because of the longitudinal growth of wormlike micelles. The shear-thickening AHSB/SDS samples were commonly composed of unbranched wormlike micelles with various length, and the shear-induced alignment of wormlike micelles was the major cause as verified by cryo-TEM. Moreover, the quantitative relationships on the critical shear rate ɣ̇_c were established, and the activation energies were obtained from the temperature-dependent ɣ̇_c.

中文翻译：

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两性离子/阴离子（AHSB/SDS）表面​​活性剂剪切增稠蠕虫状胶束的低温透射电镜和流变学研究

假设

剪切增稠胶束主要由阳离子表面活性剂制成，但在两性离子/阴离子表面活性剂中很少报道剪切增稠。由于蠕虫状胶束在剪切增稠系统中是必不可少的，因此由两性离子/阴离子表面活性剂形成的杂化蠕虫状胶束应该是常见的，并且需要阐明它们的基本特征。

实验

研究了两性离子表面活性剂同系物烷基二甲基酰胺丙基羟基磺基甜菜碱（AHSB）和十二烷基硫酸钠（SDS）在盐水中的胶束化，并系统地考虑了各种环境因素。采用光散射、流变学、zeta 电位、¹ H NMR 和低温-TEM 技术来表征 AHSB/SDS 蠕虫状胶束。

发现

AHSB/SDS 杂化蠕虫状胶束在一个宽x _SDS区域形成，赋予它们表观粘度，其中 AHSB 和 SDS 分子之间的静电和疏水相互作用至关重要。由于蠕虫状胶束的纵向生长，尾部较长的AHSB、较高的c _AHSB和c _NaCl有利于提高粘度。剪切增稠的 AHSB/SDS 样品通常由不同长度的未分枝的蠕虫状胶束组成，蠕虫状胶束的剪切诱导排列是冷冻 TEM 验证的主要原因。此外，临界剪切速率 ɣ̇ _c的定量关系成立，活化能是从温度相关的 ɣ̇ _{c 获得的}。