High-frequency dielectric polarization mechanism in water-in-oil microemulsions below percolation
High-frequency dielectric polarization mechanism in water-in-oil microemulsions below percolation
复制标题
渗透以下油包水微乳液的高频介电极化机制
DOI：
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复制
发表时间：
2000
期刊：
影响因子：
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通讯作者：
A. D. Biasio
中科院分区：
文献类型：
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作者：
F. Bordi;C. Cametti;A. D. Biasio
在这篇笔记中，我们报道了在1 MHz到1.8 GHz的频率范围内发生的油包水微乳液体系的高频介电弛豫。在研究的组成范围和温度区间(水与表面活性剂的摩尔比为40.8，体积分数从0.05到0.30)，体系表现为孤立水滴的集合，远低于渗流阈值，在那里存在更复杂的结构排列。观察到的介电谱表明，单个水滴内部存在极化机制，其特征是介电强度为几个单位，驰豫时间为1-2 ns。本文的结果支持了介电松弛是由于水-表面活性剂界面上表面坦头基团的取向相关而形成表观弛豫偶极矩的结论。这种极化机制对整个微乳液介电光谱有新的贡献，应该准确地研究其特征，以获得对这些体系的电学行为的完整描述。
In this note, we report high-frequency dielectric relaxations of water-in-oil microemulsion systems occurring in the frequency range from 1 MHz to 1.8 GHz. In the composition range and temperature interval investigated (water-to-surfactant molar ratio of 40.8 and fractional volumes from 0.05 to 0.30), the system behaves as a collection of isolated water droplets, well below the percolation threshold, where a more complex structural arrangement prevails. The observed dielectric spectra evidence a polarization mechanism occurring within the single water droplet, characterized by a dielectric strength of several units and a relaxation time of the order of 1-2 ns. The results presented here give support to the identification of the dielectric relaxation as being due to the orientational correlation of the surfactan head groups at the water-surfactant interface resulting in the formation of an apparent relaxing dipole moment. This polarization mechanism constitutes a novel contribution to the overall microemulsion dielectric spectra, whose features should be accurately investigated to gain a complete description of the electrical behaviour of these systems.