Estimation of Ionic Impurities in Poly(propylene Glycol) Diacrylate Monomers/Liquid Crystal E7 Mixtures Using Dielectric Spectroscopy
Tayeb Benkouider,
Yazid Derouiche,
Lahcene Souli,
Frédéric Dubois,
Ana Barrera,
Zohra Bouberka,
Ulrich Maschke
Affiliations
Tayeb Benkouider
Laboratoire Physico-Chimie des Matériaux et Environnement (LPCME), Faculté des Sciences Exactes et Informatique, University of Djelfa, P.O. Box 3117, Djelfa 17000, Algeria
Yazid Derouiche
Laboratoire Physico-Chimie des Matériaux et Environnement (LPCME), Faculté des Sciences Exactes et Informatique, University of Djelfa, P.O. Box 3117, Djelfa 17000, Algeria
Lahcene Souli
Laboratoire de Chimie Organique et Substances Naturelles (COSNA), Faculté des Sciences Exactes et Informatique, University of Djelfa, P.O. Box 3117, Djelfa 17000, Algeria
Frédéric Dubois
Unité de Dynamique et Structure des Matériaux Moléculaires (UDSMM), UR 4476, Université du Littoral—Côte d’Opale, CS 80699, 62228 Calais, France
Ana Barrera
Unité Matériaux et Transformations (UMET), UMR 8207, CNRS, INRAE, Centrale Lille, University Lille, 59000 Lille, France
Zohra Bouberka
Laboratoire Physico-Chimique des Matériaux, Catalyse et Environnement (LPCMCE), Université des Sciences et de la Technologie Mohammed Boudiaf d’Oran (USTO-MB), Oran 31000, Algeria
Ulrich Maschke
Unité Matériaux et Transformations (UMET), UMR 8207, CNRS, INRAE, Centrale Lille, University Lille, 59000 Lille, France
The study investigated the effect of the molecular weight of three difunctional poly(propylene glycol) diacrylates on the temperature-dependent ionic conductivity of these monomers and their blends with an eutectic nematic liquid crystal mixture (E7). The results revealed two distinct regions. At low temperatures, ionic conduction can be described by the Vogel–Tamman–Fulcher (VTF) equation, while at high temperatures, the conductivity data follow the prediction of the Arrhenius model. The Arrhenius and VTF parameters and their corresponding activation energies were determined using the least squares method. In addition, a conductivity analysis based on an ionic hopping model is proposed. Estimates of ion concentrations and diffusion constants were calculated. It was found that both the ionic concentration and the diffusion constant decrease with the increase in the molecular weight of the monomers. The static dielectric permittivity decreases in the following order: TPGDA, PPGDA540, and PPGDA900. This can be explained by the higher dipole moment of TPGDA, which is caused by an enhanced volume density of carbonyl groups.
