Water sorption and polymer dynamics in hybrid poly(2-hydroxyethyl-co-ethyl acrylate)/silica hydrogels

Stathopoulos, A; Klonos, P; Kyritsis, A; Pissis, P; Christodoulides, C; Rodriguez Hernandez, JC; Monleon Pradas, M; Gomez Ribelles, JL

dc.contributor.author	Stathopoulos, A	en
dc.contributor.author	Klonos, P	en
dc.contributor.author	Kyritsis, A	en
dc.contributor.author	Pissis, P	en
dc.contributor.author	Christodoulides, C	en
dc.contributor.author	Rodriguez Hernandez, JC	en
dc.contributor.author	Monleon Pradas, M	en
dc.contributor.author	Gomez Ribelles, JL	en
dc.date.accessioned	2014-03-01T01:34:50Z
dc.date.available	2014-03-01T01:34:50Z
dc.date.issued	2010	en
dc.identifier.issn	0014-3057	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/20892
dc.subject	Hydrogels	en
dc.subject	Poly(2-hydroxyethyl-co-ethyl acrylate)	en
dc.subject	Silica	en
dc.subject	Thermally Stimulated Depolarization Currents	en
dc.subject	Water sorption isotherms	en
dc.subject.classification	Polymer Science	en
dc.subject.other	Copolymer compositions	en
dc.subject.other	Critical region	en
dc.subject.other	Distilled water	en
dc.subject.other	Dry state	en
dc.subject.other	Ethyl acrylates	en
dc.subject.other	Hybrid copolymer	en
dc.subject.other	Hydration properties	en
dc.subject.other	Hydrophilic regions	en
dc.subject.other	Hydroxyl groups	en
dc.subject.other	Inorganic network	en
dc.subject.other	Nano scale	en
dc.subject.other	Organic compositions	en
dc.subject.other	Organic phase	en
dc.subject.other	Poly(2-hydroxyethyl-co-ethyl acrylate)	en
dc.subject.other	Polymer dynamics	en
dc.subject.other	Polymer networks	en
dc.subject.other	Rotational motion	en
dc.subject.other	Secondary relaxation process	en
dc.subject.other	Silica content	en
dc.subject.other	Silica networks	en
dc.subject.other	Sol-gel methods	en
dc.subject.other	Structural homogeneity	en
dc.subject.other	Temperature intervals	en
dc.subject.other	Thermally stimulated depolarization currents	en
dc.subject.other	Water activity	en
dc.subject.other	Water cluster	en
dc.subject.other	Water molecule	en
dc.subject.other	Water sorption	en
dc.subject.other	Water sorption isotherms	en
dc.subject.other	Water vapor atmosphere	en
dc.subject.other	Adsorption isotherms	en
dc.subject.other	Atmospheric temperature	en
dc.subject.other	Copolymerization	en
dc.subject.other	Depolarization	en
dc.subject.other	Fluorine containing polymers	en
dc.subject.other	Glass transition	en
dc.subject.other	Hydrates	en
dc.subject.other	Hydration	en
dc.subject.other	Hydrogels	en
dc.subject.other	Molecular dynamics	en
dc.subject.other	Organic polymers	en
dc.subject.other	Phase separation	en
dc.subject.other	Polymers	en
dc.subject.other	Relaxation processes	en
dc.subject.other	Silica	en
dc.subject.other	Sol-gel process	en
dc.subject.other	Sorption	en
dc.subject.other	Space probes	en
dc.subject.other	Water vapor	en
dc.subject.other	Water content	en
dc.title	Water sorption and polymer dynamics in hybrid poly(2-hydroxyethyl-co-ethyl acrylate)/silica hydrogels	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.eurpolymj.2009.10.014	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.eurpolymj.2009.10.014	en
heal.language	English	en
heal.publicationDate	2010	en
heal.abstract	This work probes the hydration properties and molecular dynamics of hybrid poly(hydroxyethyl-co-ethyl acrylate)/silica hydrogels. Two series of hybrid copolymers were prepared by simultaneous polymerization and silica preparation by sol-gel method, the first with hydroxyethyl acrylate/ethyl acrylate (HEA/EA) composition at 100/0, 90/10, 70/30, 50/50, 30/70, 10/90 and fixed silica content at 20 wt.%, and the second with fixed HEA/EA organic composition at 70/30 and 0, 5, 10 and 20 wt.% of silica. The hydration properties of these systems were studied at 25 degrees C by exposure to several controlled water vapor atmospheres (water activities 0-0.98) in sealed jars and by immersion in distilled water. Finally, the molecular dynamics of the hydrated hybrids at several levels of hydration was probed with Thermally Stimulated Depolarization Currents (TSDC) in the temperature interval between -150 and 20 degrees C. The results indicate that a critical region of silica content between 10 and 20 wt.% exists, above which silica is able to form an inorganic network. This silica network prevents the expansion of water clusters inside the hydrogels and subsequently the total stretching of the polymer network without obstructing the water sorption at the first stages of hydration from the dry state. As concerns the copolymer composition, the presence of EA reduces water sorption and formation of water clusters affecting directly to the hydrophilic regions. The TSDC thermograms reveal the presence of a single primary main broad peak denoted as alpha(cop) relaxation process, which is closely related to the copolymer glass transition, and of a secondary relaxation process denoted as beta(sw) relaxation, which originates from the rotational motions of the lateral hydroxyl groups with attached water molecules. The single alpha(cop) implies structural homogeneity at the nanoscale in HEA-rich samples (x(HEA) > 0.5), while for high EA content (x(EA) >= 0.5) phase separation is detected. Both relaxation processes show strong dependence on water content and organic phase composition. (C) 2009 Elsevier Ltd. All rights reserved.	en
heal.publisher	PERGAMON-ELSEVIER SCIENCE LTD	en
heal.journalName	European Polymer Journal	en
dc.identifier.doi	10.1016/j.eurpolymj.2009.10.014	en
dc.identifier.isi	ISI:000273879900011	en
dc.identifier.volume	46	en
dc.identifier.issue	1	en
dc.identifier.spage	101	en
dc.identifier.epage	111	en