Dielectric Study of Tetraalkylammonium and Tetraalkylphosphonium Levulinate Ionic Liquids

International Journal of Molecular Sciences

Andrea Mezzetta¹  Lorenzo Guazzelli¹  Angelica Mero¹  Christos Tsonos²  Sotiria Kripotou³  Ilias Stavrakas³  Konstantinos Moutzouris³  Georgios Tsonos³ 

[1] Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy;Department of Physics, University of Thessaly, 35100 Lamia, Greece;Laboratory of Electronic Devices and Materials, Department of Electrical and Electronics Engineering, University of West Attica, 12244 Athens, Greece;

关键词: ionic liquids;    electrical conductivity;    dielectric properties;   

DOI  :  10.3390/ijms23105642

来源: DOAJ

【 摘 要 】

Broadband dielectric spectroscopy in a broad temperature range was employed to study ionic conductivity and dynamics in tetraalkylammonium- and tetraalkylphosphonium-based ionic liquids (ILs) having levulinate as a common anion. Combining data for ionic conductivity with data obtained for viscosity in a Walden plot, we show that ionic conductivity is controlled by viscosity while a strong association of ions takes place. Higher values for ionic conductivities in a broad temperature range were found for the tetraalkylphosphonium-based IL compared to its ammonium homolog in accordance with its lower viscosity. Levulinate used in the present study as anion was found to interact and associate stronger with the cations forming ion-pairs or other complexes compared to the NTf₂ anion studied in literature. In order to analyze dielectric data, different fitting approaches were employed. The original random barrier model cannot well describe the conductivity especially at the higher frequencies region. In electric modulus representation, two overlapping mechanisms contribute to the broad low frequencies peak. The slower process is related to the conduction mechanism and the faster to the main polarization process of the complex dielectric permittivity representation. The correlation of the characteristic time scales of the previous relaxation processes was discussed in terms of ionic interactions.

【 授权许可】

Unknown