Water sorption characteristics of poly(2-hydroxyethyl acrylate)/silica nanocomposite hydrogels

Pandis, C; Spanoudaki, A; Kyritsis, A; Pissis, P; Hernandez, JCR; Gomez Ribelles, JL; Monleon Pradas, M

dc.contributor.author	Pandis, C	en
dc.contributor.author	Spanoudaki, A	en
dc.contributor.author	Kyritsis, A	en
dc.contributor.author	Pissis, P	en
dc.contributor.author	Hernandez, JCR	en
dc.contributor.author	Gomez Ribelles, JL	en
dc.contributor.author	Monleon Pradas, M	en
dc.date.accessioned	2014-03-01T01:37:33Z
dc.date.available	2014-03-01T01:37:33Z
dc.date.issued	2011	en
dc.identifier.issn	0887-6266	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/21550
dc.subject	diffusion	en
dc.subject	hydrogels	en
dc.subject	nanocomposites	en
dc.subject	silica	en
dc.subject	water sorption	en
dc.subject.classification	Polymer Science	en
dc.subject.other	Diffusion Coefficients	en
dc.subject.other	Hydroxy groups	en
dc.subject.other	Inorganic network	en
dc.subject.other	Liquid Phase	en
dc.subject.other	Mean values	en
dc.subject.other	Nanocomposite hydrogels	en
dc.subject.other	Organic networks	en
dc.subject.other	Percolation thresholds	en
dc.subject.other	Poly(2-hydroxyethyl acrylate)	en
dc.subject.other	Room temperature	en
dc.subject.other	Silica content	en
dc.subject.other	Silica nanocomposites	en
dc.subject.other	Vapor Phase	en
dc.subject.other	Water activity	en
dc.subject.other	Water molecule	en
dc.subject.other	water sorption	en
dc.subject.other	Water uptake	en
dc.subject.other	Diffusion	en
dc.subject.other	Hydrogels	en
dc.subject.other	Nanocomposites	en
dc.subject.other	Percolation (computer storage)	en
dc.subject.other	Percolation (fluids)	en
dc.subject.other	Percolation (solid state)	en
dc.subject.other	Silica	en
dc.subject.other	Sol-gel process	en
dc.subject.other	Solvents	en
dc.subject.other	Sorption	en
dc.subject.other	Water vapor	en
dc.subject.other	Water content	en
dc.title	Water sorption characteristics of poly(2-hydroxyethyl acrylate)/silica nanocomposite hydrogels	en
heal.type	journalArticle	en
heal.identifier.primary	10.1002/polb.22225	en
heal.identifier.secondary	http://dx.doi.org/10.1002/polb.22225	en
heal.language	English	en
heal.publicationDate	2011	en
heal.abstract	Water sorption in hydrogels based on nanocomposites of poly(2-hydroxyethyl acrylate) (PHEA) and silica, prepared by simultaneous polymerization and sol-gel process, were studied gravimetrically over wide ranges of silica content, both below and above the percolation threshold of about 15% wt for the formation of a continuous inorganic network interpenetrated with the organic network. Measurements were performed at room temperature from the vapor phase, both at equilibrium and dynamic, for selected values of water activity αw between 0 and 0.95, and from the liquid phase. In the nanocomposite hydrogels, the overall water uptake from the vapor phase is practically the same as in pure PHEA below the percolation threshold, whereas it is reduced above the percolation threshold, in particular at high αw values where swelling becomes significant. Water clustering sets in at around 14 vol % (10 wt %) of water independently of composition, whereas the mean value of water molecules in a cluster decreases at high silica contents. In immersion experiments water uptake decreases as silica content increases to the percolation threshold of about 15 wt % and is then almost independent of composition. A scheme is proposed, which explains these results in terms of the existence of micelles, where a number of hydrophilic hydroxy groups are linked together, and their disentaglement by immersion into water. Diffusion coefficients of water depend on water content and are reduced on addition of silica above the percolation threshold. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011 Polymeric hydrogels are macromolecular networks able to absorb large water amounts without being dissolved. Their inherent high water uptake capability leads to decreased mechanical resistance in the swollen state but also yields a high water diffusion coefficient. The mechanical properties of the swollen gel are shown to be improved by inclusion of a silica phase within the polymer network. In the resulting nanocomposites, water uptake is observed to decrease as silica content increases, up to the percolation threshold of about 15% wt, above which it becomes almost independent of composition. The Diffusion coefficients of water are also reduced on addition of silica above the percolation threshold. Copyright © 2011 Wiley Periodicals, Inc.	en
heal.publisher	WILEY-BLACKWELL	en
heal.journalName	Journal of Polymer Science, Part B: Polymer Physics	en
dc.identifier.doi	10.1002/polb.22225	en
dc.identifier.isi	ISI:000288967200005	en
dc.identifier.volume	49	en
dc.identifier.issue	9	en
dc.identifier.spage	657	en
dc.identifier.epage	668	en