In this work, nuclear magnetic resonance (NMR) spectroscopy is used to investigate surfactant phase behavior over a broad concentration region. This technique is an adaptation of a previously developed method applied to detect the critical micelle concentration (CMC) of surfactants. In this method, a surfactant concentration is correlated to the normalized intensity, or area, of the NMR signal for each surfactant. In this procedure a linear relationship develops on either side of the CMC, with a distinct change in slope where the primary phase change occurs. The research conducted herein investigates the NMR response at higher surfactant concentration, where the phase change consists of a change in micelle shape or other structural configurations. These secondary phase transitions can be expected from 10 to 90 wt.%, where the CMC measurements are conducted at concentrations <1 wt.%. The solutions were also analyzed with dynamic light scattering (DLS) and a cross-polarizer microscope to confirm suspected detected phase changes. Visible changes in the rheological response were observed and therefore carefully examined. In a large part, the results seen with all methods corresponded with visible differences in the surfactant solutions and detected changes in the NMR protocol.

在这项工作中，核磁共振（NMR）光谱用于研究宽浓度区域内的表面活性剂相行为。该技术是对先前开发的用于检测表面活性剂的临界胶束浓度（CMC）的方法的改进。在这种方法中，表面活性剂的浓度与每种表面活性剂的NMR信号的标准化强度或面积相关。在此程序中，在CMC的任一侧均会形成线性关系，其中发生主相位变化的斜率会发生明显变化。本文进行的研究调查了较高表面活性剂浓度下的NMR响应，其中相变包括胶束形状或其他结构构型的变化。这些次级相变可望占10％至90％（重量），其中CMC测量是在<1 wt。％的浓度下进行的。还使用动态光散射（DLS）和交叉偏振镜对溶液进行了分析，以确认可疑的检测到的相变。观察到流变响应的可见变化，因此进行了仔细检查。在所有方法中看到的结果大部分都与表面活性剂溶液中的可见差异和NMR方案中检测到的变化相对应。