A Study of the Dielectric Behaviour and the Liquid Structure of a Ternary Solvent System

Abstract

The static dielectric constant of the [DMF(1) + ME(2) + DME(3)] ternary mixtures was measured as a function of temperature (25 < or = t/degrees C < or = 80) and composition, over the whole mole fraction range 0 < or = chi,chi2,chi3 < or = 1. The experimental values were processed by an empirical equation accounting for the dependence epsilon = epsilon(T, phi(i)), where phi(t) is the volume fraction of the components. A comparison between calculated and experimental data shows that this fitting relationship can be effectively employed to predict epsilon values in correspondence to experimental data gaps. Starting from the experimental measurements, some derived quantities such as molar polarisation (P), and excess counterpart (PE) were obtained. Both the excess properties, epsilonE and PE, take values partly positive and partly negative under all experimental conditions. The values of the excess quantities are indicative of the presence of specific interactions among different components in the mixtures.

EQCM study of the p- and n-doping processes of a poly[4,4′-bis(butylsulphanyl)-2,2′-bithiophene]

“…It is not even possible to discard the hypothesis that some ClO À 4 ions are still present inside the polymer after the polymerisation process and that they somehow allow the polymer to charge. Referring to the results found by us and reported in [39], this would be in agreement with the unexpectedly high conductivity of polythiophene films in pure solvent, when using micro- electrodes. Another explanation could be that only a small portion of the polymer can 'physically' undergo the p-doping process with TBABPh 4 ; this could be, for example, a thin layer directly in contact with the solutions or, more plausibly, a fraction of the deposit with large enough pores to allow the counterions entrance.…”

Differential Pulse Techniques on Modified Conventional‐Size and Microelectrodes. Electroactivity of Poly[4,4′‐bis(butylsulfanyl)‐2,2′‐bithiophene] Coating Towards Dopamine and Ascorbic Acid Oxidation

“…Based on previous results with modified microelectrode in low conducting media [19,20], we tested the capability of DPV technique in aqueous solution containing a buffer concentration, i.e., a supporting electrolyte concentration, as low as 10 À4 M; such a condition is comparable with buffer capacity and ionic strength of a wide number of natural systems. Figure 6 shows DPV curves recorded in the absence and in the presence of H 2 Q, respectively.…”

“…The possibility of preparing electrochemical amperometric sensors that capitalize on the physical and chemical characteristics of modified electrodes, additionally capable of efficiently working in low conductive media, has become a realistic goal [20].…”

The permittivity of thermodynamically ideal liquid mixtures and the excess relative permittivity of binary dielectrics

“…which validates the hypothesis advanced by two of us 22 in attempting to define ideal dielectric behaviour and adopted by Tassi and co-workers. 4,23 Summing up the mixing rules for electric properties of thermodynamically ideal liquid mixtures, we observe that the molar electric dipole [eqn (27)] follows the pattern established for intensive molar Gibbsian thermodynamic properties, 24 such as the molar volume, and that the permittivity [eqn (33)], relative permittivity [eqn (32)], dielectric polarization [eqn (34)] and electric susceptibility [eqn (37)] are patterned after intensive volume-specific Gibbsian properties, 24 such as the isothermal compressibility.…”

“…In the field of liquid mixtures, however, two main positions consolidated, one advocating a mole-fraction mixing law 3 and the other a volume-fraction mixing law. 4 Although scarcely used, mass fractions were still employed in the late 20th century for representing ideal dielectric behaviour. 5,6 This choice is not a lesser matter.…”