Thermal transitions and dynamics in nanocomposite hydrogels

Kyritsis, A; Spanoudaki, A; Pandis, C; Hartmann, L; Pelster, R; Shinyashiki, N; Rodriguez Hernandez, JC; Gomez Ribelles, JL; Monleon Pradas, M; Pissis, P

dc.contributor.author	Kyritsis, A	en
dc.contributor.author	Spanoudaki, A	en
dc.contributor.author	Pandis, C	en
dc.contributor.author	Hartmann, L	en
dc.contributor.author	Pelster, R	en
dc.contributor.author	Shinyashiki, N	en
dc.contributor.author	Rodriguez Hernandez, JC	en
dc.contributor.author	Gomez Ribelles, JL	en
dc.contributor.author	Monleon Pradas, M	en
dc.contributor.author	Pissis, P	en
dc.date.accessioned	2014-03-01T11:46:35Z
dc.date.available	2014-03-01T11:46:35Z
dc.date.issued	2011	en
dc.identifier.issn	13886150	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/37957
dc.subject	Electrical conductivity	en
dc.subject	Glass transition	en
dc.subject	Poly(hydroxyethyl acrylate-co-ethyl acrylate)/silica hydrogels	en
dc.subject	Segmental dynamics	en
dc.title	Thermal transitions and dynamics in nanocomposite hydrogels	en
heal.type	other	en
heal.identifier.primary	10.1007/s10973-011-2093-5	en
heal.identifier.secondary	http://dx.doi.org/10.1007/s10973-011-2093-5	en
heal.publicationDate	2011	en
heal.abstract	Hydrogels based on nanocomposites of statistical poly(hydroxyethyl acrylate-co-ethyl acrylate) and silica, prepared by simultaneous copolymerization and generation of silica nanoparticles by sol-gel process at various copolymer compositions and silica contents, characterized by a fine dispersion of filler, were investigated with respect to glass transition and polymer dynamics by dielectric techniques. These include thermally stimulated depolarization currents and dielectric relaxation spectroscopy, covering together broad ranges of frequency and temperature. In addition, equilibrium water sorption isotherms were recorded at room temperature (25 °C). Special attention was paid to the investigation of effects of silica on glass transition, polymer dynamics (secondary γ and βsw relaxations and segmental α relaxation), and electrical conductivity in the dry systems (xerogels) and in the hydrogels at various levels of relative humidity/water content. An overall reduction of molecular mobility is observed in the nanocomposite xerogels, in particular at high silica contents. Analysis of the results and comparison with previous work on similar systems enable to discuss this reduction of molecular mobility in terms of constraints to polymeric motion imposed by interfacial polymer-filler interactions and by the formation of a continuous silica network interpenetrated with the polymer network at filler contents higher than about 15 wt%. © 2011 Akadémiai Kiadó, Budapest, Hungary.	en
heal.journalName	Journal of Thermal Analysis and Calorimetry	en
dc.identifier.doi	10.1007/s10973-011-2093-5	en
dc.identifier.spage	1	en
dc.identifier.epage	12	en