阴离子表面活性剂SDBS胶束溶液的介电弛豫行为

用射频介电谱方法研究了0.1-80 mmol·L-1浓度的十二烷基苯磺酸钠(SDBS)水溶液体系的介质弛豫行为. 测量发现频率接近107 Hz时, 在临界胶束浓度(CMC)附近出现显著的介电弛豫现象. 采用Cole-Cole函数拟合SDBS体系介电数据, 其拟合参数具有明显变化规律: 介电增量(△ε)随SDBS摩尔浓度(cs)的增加而增大, 表现为两种线性关系, 并在cs=36 mmol·L-1附近出现拐点; 特征弛豫时间(τ0)却在cs=45 mmol·L-1出现极小值. 利用胶束电模型分析了介电弛豫机制, 认为束缚Na+对离子数量和胶束体积变化是引起介电增量和特征弛豫时间变化的两个重要原因.

Dielectric Relaxation Behavior of Anionic Surfactant SDBS Micellar Solutions

The dielectric relaxation behavior of the sodiumdodecyl benzene sulfonate (SDBS) surfactant was investigated in a concentration range from0.1 to 80 mmol·L-1 by dielectric relaxation spectroscopy (DRS) method. Near the critical micelle concentration (CMC) of SDBS, significant relaxation phenomena of SDBS solutions around the frequency 107 Hz were observed. The dielectric data of the overall concentration were fitted by using the Cole-Cole equation, which revealed information about the relationship between dielectric parameters and concentration. Although the relaxation increment (△ε) increased with the concentration of SDBS (cs), this change exhibited two kinds of linear relationship, which intersected at an inflexion near 36 mmol·L-1. On the other hand, the curve of relaxation time (τ0) and concentration reached the lowest point at 45 mmol·L -1. Based on the spherical micelle model, the dielectric phenomena are due to the amount of bound Na+ counter-ions and the change in micellar volume.