The dynamics of water in nanoporous silica studied by dielectric spectroscopy

Spanoudaki, Anna; Albela, Belén; Bonneviot, Laurent; Peyrard, Michel

doi:10.1140/epje/i2004-10101-6

Cited by 46 publications

(66 citation statements)

References 22 publications

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“…A third process, attributed to the matrix, was also detected buried in the polarization dispersion and thus impossible to quantitatively analyze. 19 A striking feature of nonmonotonic temperature dependence of the dynamics of water confined in nanoporous glasses with very large pores, 24 very small soldalite cages of faujasite 25 and porous silica ͑SBA15͒ with larger pore sizes than our present system 22 has previously been reported. The dynamics of the confined water in these cases became faster with increasing temperature but reached a maximum at 270-310 K. Thereafter the dynamics rapidly became much slower with increasing temperature.…”

Section: Introductionsupporting

confidence: 62%

“…19. Our findings indicate rather hydration independent relaxation time and shape parameters for process 2.…”

Section: B the Dynamics Of Amorphous Water At Low Temperaturesmentioning

confidence: 58%

“…Possibly, the hydration dependence of the electrode polarization is responsible for apparent shifts of the peaks in Ref. 19. Furthermore, the presence of ice in the pores, as shown in Ref.…”

Section: B the Dynamics Of Amorphous Water At Low Temperaturesmentioning

confidence: 90%

“…In the only previous study of the hydration dependence of the dynamics the motions of hydroxyl groups and amorphous water have been separated and reported to show a strong hydration level ͑H͒ dependence. 19 With increasing H the water relaxations had an increasing activation energy. Simultaneously, the OH groups showed a drastic decrease of the high temperature asymptote of the relaxation time.…”

Section: Introductionmentioning

confidence: 99%

“…41 ͑MCM-41͒ have the most homogeneous and well defined pore size distribution in the range of 1 -10 nm. 17 Dielectric studies of water confined in MCM-41 materials [18][19][20] and alike [21][22][23] have been published. The spectra from these studies show the dynamical contribution of water superimposed on a large polarization dispersion, probably due to electrode polarization.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Investigating hydration dependence of dynamics of confined water: Monolayer, hydration water and Maxwell–Wagner processes

Sjöström

Swenson

Bergman

et al. 2008

The Journal of Chemical Physics

115

166

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The dynamics of water confined in silica matrices MCM-41 C10 and C18, with pore diameter of 21 and 36 Å, respectively, is examined by broadband dielectric spectroscopy ͑10 −2 -10 9 Hz͒ and differential scanning calorimetry for a wide temperature interval ͑110-340 K͒. The dynamics from capillary condensed hydration water and surface monolayer of water are separated in the analysis. Contrary to previous reports, the rotational dynamics are shown to be virtually independent on the hydration level and pore size. Moreover, a third process, also reported for other systems, and exhibiting a saddlelike temperature dependence is investigated. We argue that this process is due to a Maxwell-Wagner process and not to strongly bound surface water as previously suggested in the literature. The dynamics of this process is strongly dependent on the amount of hydration water in the pores. The anomalous temperature dependence can then easily be explained by a loss of hydration water at high temperatures in contradiction to previous explanations.

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Section: Introductionsupporting

confidence: 62%

“…19. Our findings indicate rather hydration independent relaxation time and shape parameters for process 2.…”

Section: B the Dynamics Of Amorphous Water At Low Temperaturesmentioning

confidence: 58%

Section: B the Dynamics Of Amorphous Water At Low Temperaturesmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Investigating hydration dependence of dynamics of confined water: Monolayer, hydration water and Maxwell–Wagner processes

Sjöström

Swenson

Bergman

et al. 2008

The Journal of Chemical Physics

115

166

View full text Add to dashboard Cite

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Probing the dynamics of water in chitosan polymer films by dielectric spectroscopy

Murugaraj¹,

Mainwaring²,

Tonkin³

et al. 2010

J of Applied Polymer Sci

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Chitosan biopolymers are increasingly being used in advanced biomedical applications, where aqueous interactions profoundly influence their physical properties and also their in vivo biomolecular and cellular activity. Here, hydration of chitosan films is studied by dielectric spectroscopy in a conventional constraining plate configuration and compared with free standing films. Film hydration proceeds by an initial water uptake followed by a spontaneous dehydration (deswelling) even in saturated atmospheres. At water contents above a critical value, $ 9.5 wt % a dielectric loss resonance peak (b wet ) arises from relaxation of evolving chitosan-water complexes, below this value insufficient interchain space for oscillation of these complexes prevents b wet appearing. The b wet frequency was related to water content by a power law with the frequency changing by $ 3 orders of magnitude.Importantly the scaling exponents (slopes) differed significantly for unconstrained (free standing) and volume constrained films indicating the effect of internal stresses in constrained films. Both dielectric and conductivity behavior were influenced by internal constraining stresses affecting both oscillatory motion and charge mobility. In biomedical devices, biopolymers may be free standing, surface adhered, or enclosed structures imposing different internal stresses on polymer chains and the mobility of their segments. Dielectric spectroscopy can examine these influences on dielectric and electrical characteristics, which play a critical role in biomolecular interactions.

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Proton Conductivity versus Acidic Strength of One‐Pot Synthesized Acid‐Functionalized SBA‐15 Mesoporous Silica

et al. 2011

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This paper reports on the one‐pot synthesis and characterization of the functionalized mesoporous SBA‐15 silica, which contains two loadings of the different acid groups [CO2H, PO(OH)2 and SO3H]. The thermodynamic features of the water that was confined in these porous silicas was investigated by Differential Scanning Calorimetry (DSC). The results showed that the melting behaviour of the confined water was mainly governed by the pore diameter and, as a consequence, indicated that the chemical “decoration” of the porous surface did not play a key role in the water thermodynamics. On the contrary, the proton conductivity of the hydrated mesoporous materials, which was examined under a wide range of temperatures (–100 to 70 °C), was strongly dependent on both the physical state of the confined water and the acidity of the functional groups that were located at the porous surface. The proton conductivity was shown to be directly related to the pKa and the density of the functional groups attached to the mesopore surface. The high conductivity values that were obtained at a low temperature when the confined water is frozen, led us to postulate that the SO3H‐functionalized SBA‐15 sample could be a promising candidate for electrolyte solid applications in fuel cells.

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The dynamics of water in nanoporous silica studied by dielectric spectroscopy

Cited by 46 publications

References 22 publications

Investigating hydration dependence of dynamics of confined water: Monolayer, hydration water and Maxwell–Wagner processes

Investigating hydration dependence of dynamics of confined water: Monolayer, hydration water and Maxwell–Wagner processes

Probing the dynamics of water in chitosan polymer films by dielectric spectroscopy

Proton Conductivity versus Acidic Strength of One‐Pot Synthesized Acid‐Functionalized SBA‐15 Mesoporous Silica

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