Model of Noncritical Concentration Fluctuations in Binary Liquids. Verification by Ultrasonic Spectrometry of Aqueous Systems and Evidence of Hydrophobic Effects

Rupprecht, A.; Kaatze, U.

doi:10.1021/jp9908810

Cited by 36 publications

(52 citation statements)

References 20 publications

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“…Examples of such non-ideal behavior in the binary mixture of water and amphiphilic solutes are varied and well-studied [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Sometimes the anomaly is strongest at surprisingly low solute concentrations.…”

Section: Introductionmentioning

confidence: 99%

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies

Banerjee

Furtado

Bagchi

2014

The Journal of Chemical Physics

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Water-tert-butyl alcohol (TBA) binary mixture exhibits a large number of thermodynamic and dynamic anomalies. These anomalies are observed at surprisingly low TBA mole fraction, with xTBA ≈ 0.03 − 0.07. We demonstrate here that the origin of the anomalies lies in the local structural changes that occur due to self-aggregation of TBA molecules. We observe a percolation transition of the TBA molecules at xTBA ≈ 0.05. We note that "islands" of TBA clusters form even below this mole fraction, while a large spanning cluster emerges above that mole fraction. At this percolation threshold, we observe a lambda-type divergence in the fluctuation of the size of the largest TBA cluster, reminiscent of a critical point. Alongside, the structure of water is also perturbed, albeit weakly, by the aggregation of TBA molecules. There is a monotonic decrease in the tetrahedral order parameter of water, while the dipole moment correlation shows a weak non-linearity. Interestingly, water molecules themselves exhibit a reverse percolation transition at higher TBA concentration, xTBA ≈ 0.45, where large spanning water clusters now break-up into small clusters. This is accompanied by significant divergence of the fluctuations in the size of largest water cluster. This second transition gives rise to another set of anomalies around. Both the percolation transitions can be regarded as manifestations of Janus effect at small molecular level.

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Section: Introductionmentioning

confidence: 99%

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies

Banerjee

Furtado

Bagchi

2014

The Journal of Chemical Physics

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“…The larger difference between the microscopic relaxation time of CD W-A and CD W results in a smaller value of [ K ] min for the larger alcohol-water mixtures, compared with that of the smaller alcohol-water mixtures. Rupprecht et al 39 also suggested that the heterogeneous local structure studied by ultrasonic absorption spectra for various aqueous systems is related to the number of carbon atoms of solute, i.e., the size of alkyl chain of monohydric alcohols, poly-(ethyleneglycol)monoalkyl ethers, and urea and its derivatives.…”

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confidence: 99%

Dielectric Relaxation Time and Relaxation Time Distribution of Alcohol−Water Mixtures

et al. 2001

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Complex permittivity was measured in the frequency range from 10 MHz to 20 GHz at 25°C for water mixtures of 22 aliphatic alcohols. The molecular structures of these alcohols systematically changed with the number of carbon atoms and hydroxyl groups, and their positions in the molecules. The asymmetric shape of the frequency dependence of the dielectric loss for the primary relaxation process was observed for each mixture. The broadness of the asymmetric dielectric loss depends on the water content, and the broadest dielectric loss was observed in the water mole fraction range of 0.65 < x w < 0.85. There is a strong correlation between the broadness of dielectric loss and the number of carbon atoms in the alcohol molecule. Deviations of observed relaxation times from those estimated for ideal mixtures depend on the number of carbon atoms except for the mixtures of water and alcohols with large alkyl groups, which form a micelle-like structure. These experimental results are interpreted on the basis of a model of three kinds of cooperative domains coexisting in the mixtures.

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“…A series of spectra for mixtures of short-chain alcohols has been discussed including relaxation functions that model fluctuations in the local concentration [34] and visco-inertial as well as thermal conductivity effects due to a micro-heterogeneous liquid structure [35]. A favorable description of the alcohol/water spectra is obtained in terms of a more recent unifying model of noncritical concentration fluctuations [36]. This model is based on the assumption that Fig.…”

Section: Concentration Fluctuations Mixtures Of Alcohols and Watermentioning

confidence: 99%

“…This model is based on the assumption that Fig. 6 Maximum characteristic relaxation times τ ξ max versus number n of carbon atoms per alkyl group for some mixtures of water with alcohols, poly(ethylene glycol) monoalkyl ethers, and derivatives of urea [36]: C 2 OH, ethanol; C 2 E 1 , ethoxyethanol; C 2 U, ethylurea; C 3 OH, n-propanol; i-C 3 OH, iso-propanol; i-C 3 E 1 ; iso-propoxyethanol; C 3 U, n-propylurea; t-C 4 OH, tert-butanol; C 4 E 1 , 2-butoxyethanol; C 4 E 2 , 2-(2-butoxyethoxy)ethanol; C 4 U, n-butylurea. In the inset the excess-attenuation-per-wavelength spectrum of a solution of n-propanol (4.9 mol · L −1 , 25 • C [34]) in water is displayed.…”

Section: Concentration Fluctuations Mixtures Of Alcohols and Watermentioning

confidence: 99%

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Hydrogen Network Fluctuations of Alcohols. Evidence from Ultrasonic, Dielectric, and Shear Impedance Spectrometry

Kaatze

2011

Int J Thermophys

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Broadband dielectric spectra (1 MHz to 40 GHz) and ultrasonic attenuation spectra (300 kHz to 3 GHz) as well as frequency-dependent complex shear viscosities (6 MHz to 120 MHz) are reported for alcohols and for their mixtures with other alcohols, with alkanes, and with water. The spectra are discussed with a view to features controlling the molecular dynamics of associating liquids. Special attention is given to (i) the rotation of terminal single-hydrogen-bonded hydroxy groups of associated structures, (ii) the dominating relaxation process of the structures, involving multiply-hydrogen-bonded hydroxy groups, (iii) the alkyl chain rotational isomerization, (iv) effects of clustering in alcohol-alkane mixtures, and (v) indications of non-critical concentration fluctuations of alcohol-water mixtures. The hydrogen network fluctuations of the alcohol systems can be consistently described in terms of a wait-and-switch model of relaxation. The concentration fluctuations are well represented by a recent "unifying" theoretical model, indicating a predominant impact of hydrophobic groups in the promotion of a micro-heterogeneous structure of mixtures with water.

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Model of Noncritical Concentration Fluctuations in Binary Liquids. Verification by Ultrasonic Spectrometry of Aqueous Systems and Evidence of Hydrophobic Effects

Cited by 36 publications

References 20 publications

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies

Fluctuating micro-heterogeneity in water–tert-butyl alcohol mixtures and lambda-type divergence of the mean cluster size with phase transition-like multiple anomalies

Dielectric Relaxation Time and Relaxation Time Distribution of Alcohol−Water Mixtures

Hydrogen Network Fluctuations of Alcohols. Evidence from Ultrasonic, Dielectric, and Shear Impedance Spectrometry

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