title: Vibrational signatures of the water behaviour upon confinement in nanoporous hydrogels.
abstract: The fundamental question of how the reorganization of the hydrogen-bond (HB) network of water is influenced by the combination of nano-confinement and hydrophobic/hydrophilic solvation effects is addressed here using a spectroscopic study of water absorbed in a model, pH-sensitive polysaccharide hydrogel. The effects of temperature, hydration level and pH on the vibrational dynamics associated with the water molecules and the polymer skeleton are disentangled and analysed by a complementary and combined use of UV-Raman scattering and IR spectroscopy. The experimental data give evidence that the solvation effects in the hydrogel matrix are essentially dominated by the hydration of more hydrophobic parts of the polymer network, while the effect of pH on the HB reorganization of confined water molecules is found to be similar to that induced by cooling of the system. A tentative explanation of these results has been provided in terms of interplay between different kinds of interactions, i.e. hydrophobic vs. hydrophilic.
authors.affiliation: Elettra - Sincrotrone Trieste, Strada Statale 14 km 163.5, Area Science Park, 34149 Trieste, Italy. barbara.rossi@elettra.eu and Department of Physics University of Trento and INSTM Local Unit, via Sommarive 14, 38123 Povo, Trento, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Rossi
authors.affiliation: Department of Physics and Earth Sciences, University of Messina, Viale Ferdinando Stagno D'Alcontres 31, 98166 Messina, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Venuti
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano and INSTM local unit, Piazza L. da Vinci 32, 20133, Milano, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Mele
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano and INSTM local unit, Piazza L. da Vinci 32, 20133, Milano, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Punta
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering "G. Natta", Politecnico di Milano and INSTM local unit, Piazza L. da Vinci 32, 20133, Milano, Italy and Università degli Studi e-Campus, Via Isimbardi 10, 22060 Novedrate, Como, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Melone
authors.affiliation: Elettra - Sincrotrone Trieste, Strada Statale 14 km 163.5, Area Science Park, 34149 Trieste, Italy. barbara.rossi@elettra.eu.
authors.forename: F
authors.initials: F
authors.lastname: D'Amico
authors.affiliation: Elettra - Sincrotrone Trieste, Strada Statale 14 km 163.5, Area Science Park, 34149 Trieste, Italy. barbara.rossi@elettra.eu.
authors.forename: A
authors.initials: A
authors.lastname: Gessini
authors.affiliation: Department of Physics University of Trento and INSTM Local Unit, via Sommarive 14, 38123 Povo, Trento, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Crupi
authors.affiliation: Department of Physics University of Trento and INSTM Local Unit, via Sommarive 14, 38123 Povo, Trento, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Majolino
authors.affiliation: Department of Chemistry, University of Torino, Via Pietro Giuria 7, 10125 Torino, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Trotta
authors.affiliation: Elettra - Sincrotrone Trieste, Strada Statale 14 km 163.5, Area Science Park, 34149 Trieste, Italy. barbara.rossi@elettra.eu.
authors.forename: C
authors.initials: C
authors.lastname: Masciovecchio