Department of Electronics and Information Systems, Ghent University, B-9000 Ghent, Belgium.
Langmuir. 2011 Sep 6;27(17):10386-91. doi: 10.1021/la200424v. Epub 2011 Jul 27.
Surfactants such as Aerosol OT (AOT) are commonly used to stabilize and electrically charge nonpolar colloids in devices such as electronic ink displays. The electrical behavior of such devices is strongly influenced by the presence of charged inverse micelles, formed by excess surfactant that does not cover the particles. The presence of charged inverse micelles results in increased conductivity of the solution, affecting both the energy consumption of the device and its switching characteristics. In this work, we use transient current measurements to investigate the electrical properties of suspensions of the surfactant Aerosol OT in dodecane. No particles are added, to isolate the effect of excess surfactant. The measured currents upon application of a voltage step are found to be exponentially decaying, and can be described by an analytical model based on an equivalent electric circuit. This behavior is physically interpreted, first by the high generation rate of charged inverse micelles giving the suspension resistor like properties, and second by the buildup of layers of charged inverse micelles at both electrodes, acting as capacitors. The model explains the measurements over a large range of surfactant concentrations, applied voltages, and device thicknesses.
表面活性剂（如气溶胶 OT（AOT））通常用于稳定和使非极性胶体在电子墨水显示器等设备中带电。此类设备的电气行为受带电荷的反胶束的存在强烈影响，这些反胶束由未覆盖颗粒的过量表面活性剂形成。带电荷的反胶束的存在会增加溶液的电导率，从而影响设备的能耗和开关特性。在这项工作中，我们使用瞬态电流测量来研究气溶胶 OT 在正十二烷中的悬浮液的电特性。未添加颗粒，以隔离过量表面活性剂的影响。施加电压阶跃时测量的电流呈指数衰减，并可以通过基于等效电路图的分析模型来描述。这种行为首先通过带电荷的反胶束的高生成率赋予悬浮液类似于电阻器的特性，其次通过在两个电极处形成带电荷的反胶束层，作为电容器来进行物理解释。该模型解释了在很大的表面活性剂浓度、施加电压和器件厚度范围内的测量结果。
