Liquid Fragility and the Glass Transition in Water and Aqueous Solutions

Angell, C. Austen

doi:10.1021/cr000689q

Cited by 593 publications

(582 citation statements)

References 225 publications

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“…A comparable T g has been deduced from DSC studies of different aqueous solutions, whose specific T g s extrapolate upon dilution toward the single value of 135 K [27,28].…”

Section: Introductionmentioning

confidence: 60%

Absence of molecular mobility on nano-second time scales in amorphous ice phases

Koza

Geil

Schober

et al. 2005

Phys. Chem. Chem. Phys.

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“…A comparable T g has been deduced from DSC studies of different aqueous solutions, whose specific T g s extrapolate upon dilution toward the single value of 135 K [27,28].…”

Section: Introductionmentioning

confidence: 60%

Absence of molecular mobility on nano-second time scales in amorphous ice phases

Koza

Geil

Schober

et al. 2005

Phys. Chem. Chem. Phys.

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“…Pure water has a glass transition temperature of ~135 K (obscured by a change of structure at 225 K), which increases with the addition of salts and other solutes. 24 For example, in ~5 M MgCl 2 solution, the glass-transition temperature is 170 K. 25 Measurements of electrical conductivity and viscosity as a function of temperature in aqueous electrolyte solutions have shown temperature-dependent behavior consistent with the empirical Vogel-Fulcher-Tammann (VFT) equation, 26 which predicts a critical glass-transition temperature. For viscosities under isothermal conditions, this can be expressed as a function of electrolyte concentration as 27 ( 2) where c 0 is a glass-transition concentration and P and Q are empirical parameters.…”

Section: Fig 1 (Color Online)mentioning

confidence: 93%

Glasslike behavior in aqueous electrolyte solutions

Turton

Hunger

Hefter

et al. 2008

The Journal of Chemical Physics

108

162

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When salts are added to water, the viscosity generally increases suggesting the ions increase the strength of the water's hydrogen-bond network. However, infrared pump-probe measurements on electrolyte solutions have found that ions have no influence on the rotational dynamics of water molecules implying no enhancement or breakdown of the hydrogen-bond network. Here we report optical Kerr-effect and dielectric relaxation spectroscopic measurements, which have enabled us to separate the effects of rotational and transitional motions of the water molecules. These data show that electrolyte solutions behave like a supercooled liquid approaching a glass transition in which rotational and translational molecular motions are decoupled. It is now possible to understand previously conflicting viscosity data, nuclear magnetic resonance relaxation, and ultrafast infrared spectroscopy in a single unified picture.It is well known that when salts are added to water the viscosity typically increases, suggesting that the ions alter the hydrogen-bond network of the water, 1 which appears to be confirmed by, for example, neutron diffraction experiments. 2 However, recent ultrafast infrared pump-probe measurements on electrolyte solutions have found that ions do not influence the rotational dynamics of water molecules suggesting that there is no enhancement or breakdown of the hydrogen-bond network in liquid water. 3 As the effect of ions and ionic moieties on the structure of water is important for understanding protein stability, enzymatic reactions, and substrate binding, it is crucial to resolve this paradox. 4 Here we report ultrafast optical Kerr effect 5 (OKE) and dielectric relaxation 6 (DR) spectroscopy measurements, which show that salt solutions behave like a supercooled liquid approaching a glass transition, where rotational and translational molecular motions become decoupled. The rotational motions of bulk water molecules -observed as an -relaxation in DR -are essentially independent of concentration. The translational motions seen in OKE spectroscopy can be understood as a -relaxation 7 and their dynamics become increasingly inhomogeneous with increasing salt concentration. This insight reconciles previously conflicting viscosity data, 8 nuclear magnetic resonance relaxation, 9 and ultrafast infrared spectroscopy 3 data in a single unifying picture.When simple inorganic salts are added to water, the viscosity typically increases ( see FIG. 1). In the relatively low concentration range (up to ~0.5 M), this is described by the semi-empirical Jones-Dole equation, 1 , which expresses the shear viscosity in terms of the viscosity of pure water 0 , salt concentration c, and parameters A and B. For many salts additional terms have to be added to describe the rapid increase in viscosity at higher concentrations. The obvious conclusion to draw from this behavior is that ions alter the structure of water. Indeed, the empirical Jones-Dole B coefficient is often used to classify ions as either structure makers (kosmotropes...

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“…[74][75][76] Hyperquenching small water samples with cooling rates of the order of 10 5 K s −1 prevents ice formation and leads to a vitrification of water at 136 K. [77][78][79] Albeit this number is still a subject of controversial discussions, 6,80,81 we used this value as T g of pure water (i.e., T g, 1 = 136 K in Eq. (8), as water is always considered the solvent and component 1 in this study).…”

Section: A Binary Solutionsmentioning

confidence: 99%

“…1 The industrial applications of glasses range from window glasses to engineering plastics, 2 silicon and photovoltaic cells, 3 food technology 4 to pharmaceutical industries 5 and cryobiology. 6 Highly viscous liquids also play a major role in nature. Jenniskens and Blake 7 speculate that most of the water in the universe resides in the glassy state.…”

Section: Introductionmentioning

confidence: 99%

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Experimental evidence for excess entropy discontinuities in glass-forming solutions

Lienhard

Zobrist

Zuend

et al. 2012

The Journal of Chemical Physics

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Glass transition temperatures T g are investigated in aqueous binary and multi-component solutions consisting of citric acid, calcium nitrate (Ca(NO 3 ) 2 ), malonic acid, raffinose, and ammonium bisulfate (NH 4 HSO 4 ) using a differential scanning calorimeter. Based on measured glass transition temperatures of binary aqueous mixtures and fitted binary coefficients, the T g of multi-component systems can be predicted using mixing rules. However, the experimentally observed T g in multicomponent solutions show considerable deviations from two theoretical approaches considered. The deviations from these predictions are explained in terms of the molar excess mixing entropy difference between the supercooled liquid and glassy state at T g . The multi-component mixtures involve contributions to these excess mixing entropies that the mixing rules do not take into account.

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Liquid Fragility and the Glass Transition in Water and Aqueous Solutions

Cited by 593 publications

References 225 publications

Absence of molecular mobility on nano-second time scales in amorphous ice phases

Absence of molecular mobility on nano-second time scales in amorphous ice phases

Glasslike behavior in aqueous electrolyte solutions

Experimental evidence for excess entropy discontinuities in glass-forming solutions

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