Dielectric analysis of CMPS-supported ionic liquids (ILs) microspheres in model gasoline by means of dielectric relaxation spectroscopy
Dielectric analysis of CMPS-supported ionic liquids (ILs) microspheres in model gasoline by means of dielectric relaxation spectroscopy
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DOI：
10.1016/j.colsurfa.2013.07.018
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发表时间：
2013-09
期刊：
影响因子：
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通讯作者：
Mingjuan Han;Mingyue Chen;H. Wan;Xiaomeng Wang;Jikui Wang;Juan Wang;K. Zhao;G. Guan
中科院分区：
文献类型：
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作者：
Mingjuan Han;Mingyue Chen;H. Wan;Xiaomeng Wang;Jikui Wang;Juan Wang;K. Zhao;G. Guan
采用介电弛豫谱（DRS）技术，在40 ~ 110 MHz频率范围内，对CMPS负载咪唑类离子液体微球在模拟汽油中的介电行为进行了实时监测。在MHz频率范围内，所有体系都观察到一个明显的介电弛豫，并确定其与界面极化密切相关。由于咪唑类离子液体以优化的空间构型固定在分散微球表面，分散微球与模型汽油之间电导率的差异导致了界面极化。同时，通过拟合Cole-Cole方程得到了所有体系的介电参数（ε l，κl，ε h，κ handf 0）。由介电参数，利用Hanai方程计算出相参数（ε m，κm，ε p和κp），用于表征非导电介质中导电颗粒悬浮液组成相的电学和结构特性。详细研究了介电参数和相参数的时间依赖性，并采用稠密颗粒悬浮的界面电动力学模型解释了这些时间依赖性。我们发现离子液体中咪唑环与噻吩之间可能存在的π-络合键和π-π相互作用对所有参数的时间依赖性起着重要的作用。此外，参数的时间依赖性表明，分散微球表面的电子密度（极化强度）随着萃取时间的增加而降低。
Real-time monitoring of dielectric behaviors of CMPS-supported imidazolium ionic liquids (ILs) microspheres in model gasoline was performed by dielectric relaxation spectroscopy (DRS) from 40 Hz to 110 MHz. One dielectric relaxation in MHz frequency range is obviously observed for all systems and determined to be closely related to the interfacial polarization. The interfacial polarization is attributed from the different conductivities between dispersed microspheres and model gasoline since imidazolium-based ionic liquids have been immobilized on the surfaces of dispersed microspheres in the form of optimized spatial configurations. Meanwhile, dielectric parameters (ɛl,κl,ɛh,κhandf0) for all the systems are obtained by fitting Cole–Cole equation to the dielectric data. From the dielectric parameters, Hanai equations are employed to calculate phase parameters (ϕ,κm,ɛpandκp), which is used to characterize the electrical and structural properties of constituent phases of suspensions of conducting particles in non-conducting medium. The time-dependences of dielectric parameters and phase parameters are investigated in detail, and interfacial electrokinetic model for suspension of dense particles has been employed for interpreting these time-dependences. Here, we found that possible π–complexation bond and π–π interaction between imidazole rings of ILs and thiophene are responsible for time-dependences of all parameters. Furthermore, the time-dependences of parameters indicate that the electron density (polarization strength) on surfaces of dispersed microspheres decreases with the increment of extraction time.