Relaxation dynamics of H-bonded liquids confined in porous silica gels by Rayleigh wing spectroscopy

Carini, G.; Crupi, V.; D’Angelo, Giovanna; Majolino, D.; Migliardo, P.; Mel’nichenko, Yu. B.

doi:10.1063/1.474605

Cited by 46 publications

(26 citation statements)

References 26 publications

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“…The two glass-forming liquids addressed below, propylene glycol and glycerol, have both been subject to dielectric investigations in confined spaces. For PG, an increase of the relaxation time and ͑equivalently͒ glass transition temperature T g has been reported in a number of studies, 43,45,53,65,66 consistent with our solvation result in 4 nm Vycor glass. Only one study reports the reverse effect of faster dynamics upon hard confinement.…”

Section: Discussionsupporting

confidence: 93%

“…Experimental approaches to the behavior of confined and interfacial liquids have used very different techniques, [3][4][5]7,[43][44][45][46][47][48] confining geometries, 2,49-52 and surface properties 8,22,53 . An attempt to sort the various experimental approaches to confined liquids by the confinement type is shown in Table II, which disregards surface treatments as an additional experimental variable.…”

Section: Discussionmentioning

confidence: 99%

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Dynamics of supercooled liquids in the vicinity of soft and hard interfaces

He¹,

Wang²,

Richert³

2005

Phys. Rev. B

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Using solvation techniques we explore the dynamics of nanoconfined and interfacial supercooled liquids near their glass transition temperatures. Confinement is accomplished by the use of porous glasses with pore diameters between 4 and 7.5 nm, and by microemulsions with droplet sizes between 2.6 and 5 nm. Via the attachment of the probe molecules to the inner surface of porous glasses filled with 3-methylpentane, the interfacial layer is measured selectively for different surface curvatures and shows an increase of the relaxation time by more than three orders of magnitude over that of the bulk liquid. This frustration is most pronounced at the pore boundary and decreases gradually across the first few nanometers distance away from the interface. Nanoconfinement realized by glass-forming microemulsions with the confining material being more fluid than the intramicellar droplets reverse the situation from frustrated dynamics in hard confinement to accelerated relaxation behavior in the case of soft boundaries. Without changing the size of the geometrical restriction of propylene glycol, hard versus soft boundary conditions changes the glass transition shift ⌬T g from +6 K to − 7 K. The findings can be rationalized on the basis of certain interfacial dynamics which differ from bulk behavior, with the penetration of this effect into the liquid being governed by the length scale of cooperativity. This picture explains both the more disperse relaxation times in confinement and the dependence of the average relaxation time on pore size.

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Section: Discussionsupporting

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Dynamics of supercooled liquids in the vicinity of soft and hard interfaces

He¹,

Wang²,

Richert³

2005

Phys. Rev. B

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“…[1][2][3] Generally speaking, two competing effects seem to play the main role in modifying the dynamics of confined water with respect to the bulk state: the interaction forces with the substrate molecules (chemical traps), and the bare geometrical confinement (physical traps), i.e., the excluded volume effect. The separation of these two contributions, whose interplay is strongly dependent on the particle density and the size of the confining system, is still a problem that has not been completely solved yet.…”

Section: Introductionmentioning

confidence: 99%

Neutron Scattering Study and Dynamic Properties of Hydrogen-Bonded Liquids in Mesoscopic Confinement. 1. The Water Case

et al. 2002

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In the present work we report a detailed spectroscopic analysis of diffusive relaxation and vibrational properties of water in bulk and confined in nanopores of Gelsil glass, at different temperatures and different hydration percentages, performed by incoherent quasi-elastic and inelastic neutron scattering, IQENS and IINS, respectively. IQENS spectra are analyzed in the framework of two different models: the confined diffusion model (CDM) and the relaxing cage model (RCM). The first one is based on the well-known random jump diffusion model for confined diffusion; the second one takes into account the R-relaxation dynamics predicted by mode coupling theory (MCT) of supercooled liquids. Finally, the analysis of IINS spectra has been addressed to the comprehension of the evolution of the one-phonon-amplitude weighted proton vibrational density of states (VDOS), Z(ω), when the water loses its peculiar bulk properties and originates a new structural environment due to its surface interaction.

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“…These materials can be prepared as high-optical-quality monoliths that have a narrow distribution of pore sizes centered about a controllable average size, and as such are conducive to studies by numerous physical techniques. [9][10][11][12][13][14][15][16][17] In a number of previous studies [18][19][20] we have employed optical Kerr effect 21,22 ͑OKE͒ spectroscopy to study the dynamics of liquids confined in these materials. These experiments demonstrated that OKE spectroscopy is a powerful means of obtaining molecular-level information about the structure and dynamics of liquids confined in nanoporous glasses.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of a wetting liquid in nanopores: An optical Kerr effect study of the dynamics of acetonitrile confined in sol-gel glasses

Loughnane

Farrer

Scodinu

et al. 1999

The Journal of Chemical Physics

109

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The orientational dynamics of acetonitrile and acetonitrile-d3 confined in nanoporous glasses have been studied using optical Kerr effect spectroscopy. The decays can be fit to the sum of three exponentials, the fastest of which corresponds to relaxation of bulk-like liquid. We present evidence that the intermediate exponential arises from the exchange of molecules bound to the pore surfaces into the bulk liquid, whereas the slowest exponential corresponds to surface relaxation. A comparison to nuclear magnetic resonance data demonstrates that the liquid at the pore surfaces is more highly ordered than that in the bulk. Surface-modification studies demonstrate that hydrogen bonding is responsible for the extreme inhibition of dynamics at the pore surfaces.

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Relaxation dynamics of H-bonded liquids confined in porous silica gels by Rayleigh wing spectroscopy

Cited by 46 publications

References 26 publications

Dynamics of supercooled liquids in the vicinity of soft and hard interfaces

Dynamics of supercooled liquids in the vicinity of soft and hard interfaces

Neutron Scattering Study and Dynamic Properties of Hydrogen-Bonded Liquids in Mesoscopic Confinement. 1. The Water Case

Dynamics of a wetting liquid in nanopores: An optical Kerr effect study of the dynamics of acetonitrile confined in sol-gel glasses

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