title: Probing the molecular connectivity of water confined in polymer hydrogels.
abstract: The molecular connectivity and the extent of hydrogen-bond patterns of water molecules confined in the polymer hydrogels, namely, cyclodextrin nanosponge hydrogels, are here investigated by using vibrational spectroscopy experiments. The proposed spectroscopic method exploits the combined analysis of the vibrational spectra of polymers hydrated with water and deuterated water, which allows us to separate and selectively investigate the temperature-evolution of the HOH bending mode of engaged water molecules and of the vibrational modes assigned to specific chemical groups of the polymer matrix involved in the physical interactions with water. As main results, we find a strong experimental evidence of a liquid-like behaviour of water molecules confined in the nano-cavities of hydrogel and we observe a characteristic destructuring effect on the hydrogen-bonds network of confined water induced by thermal motion. More interestingly, the extent of this temperature-disruptive effect is found to be selectively triggered by the cross-linking degree of the hydrogel matrix. These results give a more clear picture of the molecular mechanism of water confinement in the pores of nanosponge hydrogel and open the possibility to exploit the spectroscopic method here proposed as investigating tools for water-retaining soft materials.
authors.affiliation: Elettra Sincrotrone Trieste, Strada Statale 14 km 163.5, Area Science Park, 34149 Trieste, 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, 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, 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, Piazza L. da Vinci 32, 20133 Milano, 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.
authors.forename: V
authors.initials: V
authors.lastname: Crupi
authors.affiliation: Elettra Sincrotrone Trieste, Strada Statale 14 km 163.5, Area Science Park, 34149 Trieste, 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.
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.
authors.forename: A
authors.initials: A
authors.lastname: Gessini
authors.affiliation: Elettra Sincrotrone Trieste, Strada Statale 14 km 163.5, Area Science Park, 34149 Trieste, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Masciovecchio
mesh_terms: D003505:Cyclodextrins / Q000737:chemistry; D020100:Hydrogels / Q000737:chemistry*; D006860:Hydrogen Bonding; D049329:Nanostructures / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D003505:Cyclodextrins; D020100:Hydrogels; D011108:Polymers; D014867:Water