Showing papers by "Jan Jadżyn published in 2015"

Charge Relaxation and Stokes–Einstein Relation in Diluted Electrolyte Solution of Propylene Carbonate and Lithium Perchlorate

Abstract: Impedance spectroscopy was used for studies of electrical conductivity and electric charge relaxation in a diluted solution of propylene carbonate and lithium perchlorate (mole fraction xLiClO4 = 6 × 10–5) in the temperature range from 250 to 350 K. It was found that the viscosity behavior of the conductivity as well as the charge relaxation time related to the Li+ and ClO4– ions immersed in propylene carbonate fulfill quite well the Stokes–Einstein hydrodynamic model. An essentially limited ion-pairing process in the studied solution of a low ion concentration and considerably limited dipolar aggregation of propylene carbonate molecules are considered to be essential factors determining the dynamic behavior of the ions immersed in that strongly polar liquid.

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 (LiClO4) 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–[CH2–CH2–O]n–H chains in the efficiency of charge carriers transport in liquid glycols is discussed.

How to Enhance Sensitivity of Liquid Crystals to External Magnetic Field

Abstract: to External Magnetic Field? P. Kop£anský, N. Toma2ovi£ova, V. Gdovinova, M. Timko, N. Eber, T. Toth-Katona, J. Jadzyn, J. Honkonen and X. Chaud Institute of Experimental Physics, Slovak Academy of Sciences, Watsonova 47, 040 01 Kosice, Slovakia Institute for Solid State Physics and Optics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, H-1525 Budapest, P.O. Box 49, Hungary Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60179 Poznan, Poland Department of Physical Sciences, University of Helsinki, Gustav Hallstromin katu 2, Helsinki, Finland High Magnetic Field Laboratory, CNRS, 25 Avenue des Martyrs, Grenoble, France

Hierarchical Structure of Supramolecular Polymers Formed by N,N'-Di(2-ethylhexyl)urea in Solutions.

Abstract: Supramolecular chain polymers formed by N,N'-di(2-ethylhexyl)urea (EHU) dissolved at low concentrations (up to 0.1 mole fraction) in heptane were investigated with the use of the dielectric spectroscopy. The experimental data show an exceptional ability of the chains for the antiparallel self-aggregation due to dipole-dipole interactions, leading to an anomalous dependence of the static permittivity of EHU + heptane solutions on temperature and concentration of the urea. The primary molecular assembly into polymeric chains is therefore followed by a secondary bundling of the chains which facilitates a longitudinal translation of the chains. That peculiarity and an asymmetry of the alkyl substituent in the EHU molecule making the system a mixture of diastereoisomers of unfavorable packing of the side group, are the most probable molecular mechanisms which prevent the crystallization of EHU-the only known liquid urea derivative.

Dielectric Spectroscopy of Ferronematics Based on 6CHBT Liquid Crystal

Abstract: In our study, the dielectric behaviour of the rod-like liquid crystal (6CHBT) doped with magnetic nanoparticles of spherical shape was investigated by means of dielectric spectroscopy in the frequency range from 20 Hz to 2 MHz. A low frequency dielectric dispersion in the nematic and isotropic phases of the pure liquid crystal (LC) has been assigned to the space charge polarization. After doping the host LC with the magnetic nano particles, a nearly Debye-like relaxation process was observed with the temperature dependence obeying the Arrhenius law. Considering a possible electric double layer formation on the particle surfaces, the detected relaxation process in the doped LC can be associated with the electric double layer polarization. The experimental results point out that in the measured frequency range the space charge and interfacial effects constitute the main dielectric response. Any anchoring effects were not observed and are therefore expected to appear in higher frequencies.

Dielectric Properties of Lyotropic Magnetic Liquid Crystal

Abstract: Dielectric Properties of Lyotropic Magnetic Liquid Crystal P. Kop£anský, L. Tom£o, J. Jadzyn, J. Swiergiel, J. Majoro2ova, M. Kubov£ikova, M. Timko, M. Raj¬ak, K. ’ipo2ova, Z. Gaoova, Z. Bednarikova, N. Toma2ovicova, Chin-Kun Hu, S. Hayryan, I. Studenyak , T.M. Kovalchuk and O.V. Kovalchuk Institute of Experimental Physics, Slovak Academy of Sciences, Ko2ice, Slovakia Faculty of Aeronautics, Technical University, Ko2ice, Slovakia Institute of Molecular Physics, Polish Academy of Sciences, Pozna«, Poland Department of Biochemistry, Institute of Chemistry, P.J. Safarik University in Ko2ice, Slovakia Institute of Physics, Academia Sinica, 128 Sec.2, Academia Rd., Nankang, Taipei 11529, Taiwan Physics Faculty, Uzhhorod National University, Uzhhorod, 88000, Ukraine Institute of Semiconductor Physics, National Academy of Science of Ukraine, Kyiv, Ukraine Kyiv National University of Technologies and Design, Kyiv, Ukraine An important feature of lyotropic liquid crystals is the self-assembly of the amphiphilic molecules as supermolecular structures. We have studied the formation of nematic liquid crystal phase in solutions containing lysozyme amyloid brils and magnetic nanoparticles using oscilloscopic method. Interaction of brils with magnetic nanoparticles under the external magnetic eld resulted in bril re-arrangement. The analysis of the obtained results suggests that the decrease in conductivity of solutions in presence of magnetic eld is due to decrease of the ion mobility caused by re-arrangement of structures in the solution. The obtained results allow determination of the optimum ratio of the components which can lead to preparation of solutions with a more ordered structure in presence of magnetic eld.