Abstract

In this study, the viscosity and viscoelasticity of Gemini surfactant solutions with different molecular structures were measured, and the micelle structure formed by self-assembly in the solution was observed and measured using FESEM and DLS. The effect of the molecular structure of anionic Gemini surfactants on the rheological properties of the solution was studied systematically. The experimental results showed that the carboxylate Gemini surfactants with long hydrophobic carbon chains and a moderate spacer group have better rheological properties in aqueous solution. The carboxylate Gemini surfactant solution aggregated to form more densely, larger-sized micelle structures than the sulfonate Gemini surfactant, so its viscosity and viscoelasticity are greater. When the carbon number of the spacer group was the same (s = 2), as the carbon number of the hydrophobic chain increased (m = 14,16,18), the hydrodynamic diameter increased, the size of the micelle structures formed by self-assembly in the solution increased, the micelles aggregated more tightly, and the solution viscosity and viscoelasticity increased. When the carbon number of the hydrophobic chain was the same (m = 18), as the carbon number of the spacer group increased (s = 2,3,4), the hydrodynamic diameter first increased and then decreased, the micelle structures exhibited the phenomenon of aggregation first and then disintegration, and the solution viscosity and viscoelasticity also increased first and then later decreased. These phenomena indicated that the change of Gemini surfactant molecular structure would lead to the change of its micelle microstructure and eventually lead to the change of solution rheological properties.

摘要

本研究通过测量不同分子结构的 Gemini 表面活性剂溶液的粘度和粘弹性，利用 FESEM 和 DLS 对溶液中自组装形成的胶束结构进行了观察和测量。系统研究了阴离子Gemini表面活性剂分子结构对溶液流变性能的影响。实验结果表明，具有长疏水碳链和适度间隔基的羧酸盐Gemini表面活性剂在水溶液中具有更好的流变性能。羧酸盐Gemini表面活性剂溶液聚集形成比磺酸盐Gemini表面活性剂更致密、尺寸更大的胶束结构，因此其粘度和粘弹性更大。当间隔基的碳数相同时（s = 2），随着疏水链碳数的增加（m = 14,16,18），流体动力学直径增加，溶液中自组装形成的胶束结构尺寸增加，胶束聚集更紧密，溶液粘度增加和粘弹性增加。当疏水链碳原子数相同时（m=18），随着间隔基碳原子数的增加（s=2,3,4），流体动力学直径先增大后减小，胶束结构表现出出现先聚集后崩解的现象，溶液粘度和粘弹性也先增大后减小。