Electrochemical impedance study of the lignin-derived conducting polymer
authors Graca, MPF; Rudnitskaya, A; Faria, FAC; Evtuguin, DV; Gomes, MTSR; Oliveira, JABP; Costa, LC
nationality International
journal ELECTROCHIMICA ACTA
author keywords Multi-wall carbon nanotubes; Conducting polymer; Kraft lignin; Polyurethane; Nanocomposites; Percolation; Dielectric relaxation
keywords ELECTRICAL-PROPERTIES; CARBON NANOTUBES; PERCOLATION-THRESHOLD; COMPOSITES; POLYURETHANES; MODULUS; POLARIZATION; ELECTRODE; SYSTEMS; WATER
abstract Electrochemical impedance spectroscopy was applied to the study of conducting lignin-derived polymers to be used in all-solid-state potentiometric chemical sensors. Conducting polymers were produced by step-growth polymerization of modified eucalyptus kraft lignin with isocyanate and doped by multi-wall carbon nanotubes (MWCNTs). Lignin possesses ion-exchange properties due to the presence of a variety of functional groups, which makes it an attractive active substance for chemical sensing. Co-polymerization allows fixing lignin inside polymer matrix ensuring high stability of the resulting material. Doping of the lignin-based polyurethane with multi-wall carbon nanotubes (MWCNTs) was adopted as a mean to obtain electrically conductive system with low mass of filler. The direct current (DC) electrical conductivity and the dielectric properties of the conducting polymers have been evaluated at MWCNTs contents from 0 to 0.72% (wt.) at the frequencies between 40 Hz and 100 MHz in the temperature range - 100 to 1000 degrees C. The percolation model theory was used to describe DC and the low frequency behaviour, where the electrical conductivity and the dielectric constant were expressed by scaling laws near the threshold conduction. The lignin-based polyurethane presented low critical concentration of MWCNTs around 0.18 wt.%. The dielectric analysis was carried out using the modulus formalism and the dielectric relaxation behaviour was modelled using the Cole-Cole expression. (C) 2012 Elsevier Ltd. All rights reserved.
publisher PERGAMON-ELSEVIER SCIENCE LTD
issn 0013-4686
year published 2012
volume 76
beginning page 69
ending page 76
digital object identifier (doi) 10.1016/j.electacta.2012.04.155
web of science category Electrochemistry
subject category Electrochemistry
unique article identifier WOS:000306621200009
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