Stokes–Einstein–Nernst Relation in Dilute Electrolyte Solutions of Lithium Perchlorate in Polyethylene Glycols (200, 300, 400, and 600)

Abstract

The electrical conductivity was measured for dilute electrolyte solutions of lithium perchlorate (LiClO 4 ) in polyethylene glycols (PEG) of different molecular weights (200−600). The results were interpreted in the frame of the Stokes−Einstein−Nernst model. It was found (i) a breakdown of the model in the glycol-based polymeric matrices used and (ii) an increase of the deviation from the model predictions with increasing molecular weight of the matrix. The role of the flexibility of HO− [CH 2 −CH 2 −O] n −H chains in the efficiency of charge carriers transport in liquid glycols is discussed.

Effect of ionic contaminants on dielectric dispersion and relaxation processes over static permittivity frequency region in neat liquid poly(ethylene glycol)

“…The ε′ values of 1 MHz are taken as the static permittivity ε s (T) of liquid PEG200, and these are given in Table 1. These ε s (T) values of the neat PEG200 are found in good agreement with that of the molecular sieve dried PEG200 [8], which confirms that the concentration of unidentified ionic contaminants does not affect the static permittivity of neat liquid PEG200, and it is also true in case of Li + ClO 4 − diluted electrolyte solution of PEGs solvent [8]. Low-frequency dielectric spectroscopic studies on different static permittivity dipolar liquids (solvents) have confirmed that their ε s values are independent of ions contaminants, but the high frequency value at which steady state in ε′(f) spectrum appeared depends on the ions concentration [16,17,20].…”

“…For the liquid dielectric materials of Ohmic behaviour, their dielectric loss ε″(f) spectrum presents itself, according to straight line relation ε″(f) = σ dc /2πfε 0 , where σ dc is the direct current (dc) ionic conductivity [17][18][19][20]. This behaviour is also true for the diluted electrolyte solutions [8]. Further, Fig.…”

“…Since, PEGs are both good proton donor and proton acceptor, and therefore, they form strong intra-and inter-molecular hydrogen bonding [3,4]. Further, due to the presence of molecular chain ends hydroxyl groups and the ether oxygen in repeat units, the liquid PEGs can effectively solvate a variety of alkali and alkaline ionic salts, and therefore, these are recognized as non-aqueous solvents in preparation of liquid electrolytes [5][6][7][8] and also used as plasticizer in solid polymer electrolytes [9][10][11].…”

“…All the neat dipolar liquids possess 'natural' unidentified free ions contaminants, which are further activated by the assistance of some natural electromagnetic irradiations [19,[22][23][24]. The ionic characterization (dc conductivity and ions dynamics) in liquid electrolytes and also in solid electrolytes is mostly examined by their low-frequency dielectric and impedance measurements [8,11,21,25,26]. Therefore, it is technologically interesting to explore the detailed temperature dependent dielectric and electrical behaviour of neat PEGs using dielectric relaxation spectroscopy (DRS) of the low-frequency of electric field stimulus.…”

“…The aims of this work are: firstly, to provide the detailed experimental results of dielectric and electrical dispersion of neat PEG200 in the low-frequency region (the static permittivity frequency regime); secondly, to confirm the temperature and viscosity dependent dynamical behaviour of free ions; thirdly, to reveal the Stokes-Einstein-Nernst dependences of dc conductivity and charge relaxation time; and finally, to compare these results with the dilute electrolyte solutions of lithium perchlorate in PEGs solvents in order to explore the conduction mechanism of unidentified ionic contaminants in neat PEG200 [8]. The spectra of all the four complex dielectric and electrical quantities i.e.…”