Hydration and conductivity studies of polymer-water interactions in polyacrylamide hydrogels

Konsta, AA; Daoukaki, D; Pissis, P; Vartzeli, K

dc.contributor.author	Konsta, AA	en
dc.contributor.author	Daoukaki, D	en
dc.contributor.author	Pissis, P	en
dc.contributor.author	Vartzeli, K	en
dc.date.accessioned	2014-03-01T01:14:42Z
dc.date.available	2014-03-01T01:14:42Z
dc.date.issued	1999	en
dc.identifier.issn	0167-2738	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/13194
dc.subject	hydrogels	en
dc.subject	proton conductivity	en
dc.subject	broad-band dielectric relaxation spectroscopy (DRS)	en
dc.subject	thermally stimulated depolarization currents (TSDC)	en
dc.subject	water sorption isotherms	en
dc.subject.classification	Chemistry, Physical	en
dc.subject.classification	Physics, Condensed Matter	en
dc.subject.other	Activation energy	en
dc.subject.other	Dielectric relaxation	en
dc.subject.other	Electric conductivity of solids	en
dc.subject.other	Hydration	en
dc.subject.other	Hydrogels	en
dc.subject.other	Induced currents	en
dc.subject.other	Ionic conduction in solids	en
dc.subject.other	Isotherms	en
dc.subject.other	Polyamides	en
dc.subject.other	Porous materials	en
dc.subject.other	Sorption	en
dc.subject.other	Water	en
dc.subject.other	Dielectric relaxation spectroscopy	en
dc.subject.other	Proton conductivity	en
dc.subject.other	Thermally stimulated depolarization currents (TSDC)	en
dc.subject.other	Polyelectrolytes	en
dc.title	Hydration and conductivity studies of polymer-water interactions in polyacrylamide hydrogels	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/S0167-2738(99)00180-0	en
heal.identifier.secondary	http://dx.doi.org/10.1016/S0167-2738(99)00180-0	en
heal.language	English	en
heal.publicationDate	1999	en
heal.abstract	The conductivity and hydration mechanisms of polyacrylamide (PAA) hydrogels have been investigated by means of (a) equilibrium and dynamic water sorption isotherms, (b) thermally stimulated depolarization currents (TSDC) techniques in the temperature range 77 to 300 K and (c) broad band dielectric relaxation spectroscopy (DRS) in the frequency range 10(-2) to 10(6) Hz and the temperature range 230 to 330 K. A systematic analysis of our combined results indicates that water molecules up to a critical hydration value, h(c), of about 0.15 g of water/g of dry weight are irrotationally bound to primary hydration sites and do not contribute themselves to the dielectric spectra. This h(c) value is in accordance with equilibrium isothermal measurements on the same samples. Moreover, a reorganization of water in the hydrogels seems to take place for h greater than or equal to 0.8. The Arrhenius behaviour of DC-conductivity, sigma(dc), as well as of the loss tangent, tan delta, and electric modulus, M ", dispersions, with an activation energy of the order of 0.8 eV, suggests that the observed phenomena have a common origin and that the conductivity mechanism is not governed by the co-operative motion of the polymeric chains, the charge carriers (protons) motion occurring probably through the water-filled micropores of the hydrogel. (C) 1999 Elsevier Science B.V. All rights reserved.	en
heal.publisher	Elsevier Science Publishers B.V., Amsterdam, Netherlands	en
heal.journalName	Solid State Ionics	en
dc.identifier.doi	10.1016/S0167-2738(99)00180-0	en
dc.identifier.isi	ISI:000083122700029	en
dc.identifier.volume	125	en
dc.identifier.issue	1	en
dc.identifier.spage	235	en
dc.identifier.epage	241	en