The study of hydrophobicity in water–methanol and water–tert-butanol mixtures

Киселев, М. Г.; Ivlev, D. V.

doi:10.1016/j.molliq.2003.09.014

Cited by 29 publications

(23 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…7a, the first peak in the water-water distribution functions in water-methanol mixtures is higher than that of pure water and reaches a maximum value at methanol mole fraction x = 0.2. This tendency is consistent with previous calculations at room temperature [13][14][15] and at supercritical conditions [16]. In addition, the second peak that should be observed at around 4.5Å, which is attributed to the tetrahedral ordering of the hydrogen-bonded nearest neighbors, cannot be found.…”

Section: Radial Distribution Functions and Self-diffusion Coefficientssupporting

confidence: 93%

“…The molecular dynamics calculations will be useful for providing insight into the structure of fluid mixtures at a molecular level. Since aqueous methanol is of fundamental importance as a model system for the study of hydration, quite a few studies on computer simulations of water-methanol mixtures have been reported [13][14][15][16], in addition to direct structural studies by neutron diffraction [17,18]. However, the local structure of these mixtures in the vicinity of the critical region remains largely unknown.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Volumetric behavior of water–methanol mixtures in the vicinity of the critical region

Bulemela¹,

Tremaine²,

Ikawa³

2006

Fluid Phase Equilibria

View full text Add to dashboard Cite

Section: Radial Distribution Functions and Self-diffusion Coefficientssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Volumetric behavior of water–methanol mixtures in the vicinity of the critical region

Bulemela¹,

Tremaine²,

Ikawa³

2006

Fluid Phase Equilibria

View full text Add to dashboard Cite

“…The majority of them are performed in a rather limited (although some are broader) concentration range [44,[46][47][48], but we could not find a structural study of aqueous TBA that would really closely combine the x-ray scattering experiment and theory across the whole concentration range. Both experimental [47,49] and simulation studies [6,7,46,[50][51][52][53][54][55][56][57][58] show that mixtures of TBA and water are homogeneous on the mesoscopic scale [44,59], while on the microscopic scale heterogeneities can be observed -a feature strongly dependent on the composition of the solution. Such heterogeneities are associated with the formation of discrete local TBA-rich and water-rich regions, whose effective sizes and structure remain unclear.…”

Section: Introductionmentioning

confidence: 99%

Structural, rheological and dynamic aspects of hydrogen-bonding molecular liquids: Aqueous solutions of hydrotropic tert-butyl alcohol

Cerar

Jamnik

Pethes

et al. 2020

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

Hypothesis: The structural details, viscosity trends and dynamic phenomena in t-butanol/water solutions are closely related on the molecular scales across the entire composition range. Utilizing the experimental small-and wide-angle x-ray scattering (SWAXS) method, molecular dynamics (MD) simulations and the 'complemented-system approach' method developed in our group it is possible to comprehensively describe the structure-viscosity-dynamics relationship in such structurally versatile hydrogen-bonded molecular liquids, as well as in similar, self-assembling systems with pronounced molecular and supramolecular structures at the intra-, inter-, and supra-molecular scales. Experiments: The SWAXS and x-ray diffraction experiments and MD simulations were performed for aqueous t-butanol solutions at 25 °C. Literature viscosity and self-diffusion data were also used. Findings: The interpretive power of the proposed scheme was demonstrated by the extensive and diverse results obtained for aqueous t-butanol solutions across the whole concentration range. Four composition ranges with qualitatively different structures and viscosity trends were revealed. The experimental and calculated zero-shear viscosities and molecular self-diffusion coefficients were successfully related to the corresponding structural details. The hydrogen bonds 2 that were, along with hydrophobic effects, recognized as the most important driving force for the formation of t-butanol aggregates, show intriguing lifetime trends and thermodynamic properties of their formation. Binary System.Recently, attention has turned to substances with small molecules exhibiting only a weak amphiphilic character that are sometimes addressed as 'amphiphilic solvents' or 'solvosurfactants' [9, 10]. They can be seen as liquids exhibiting the properties of surfactants, such as 3 surface activity, self-assembly in water, co-micellization, etc. The term 'hydrotrope' is also very commonly used, even though, as reviewed by Kunz et al. [11], it comprises a broader range of amphiphilic compounds [12][13][14]. Their ternary systems are often called 'surfactant-free microemulsions' [15] or 'detergentless microemulsions' [16]. More recently Zemb et al.proposed the term 'ultraflexible microemulsions' [17], as such systems exhibit low bending rigidities.The binary aqueous solutions of such substances are especially interesting due to their strong non-ideal behavior, e.g., in terms of their viscosity, partial molar volume, excess thermodynamic properties, compressibility, and sound-attenuation coefficient [18][19][20][21][22][23]. Such behavior arises because the hydrophilic part of the molecule forms strong hydrogen-bonds (HBs) with water, while the hydrophobic part introduces a perturbation to the water's hydrogen-bonded structure and induces cooperative ordering, stemming from the hydrophobic hydration effects.However, a full understanding of the hydration structure of such systems and their non-ideal behavior is still incomplete.In our recent research we have strived to learn m...

show abstract

“…1,2 However, recent experimental and computational studies show that they are inhomogeneous over smaller length scales. Molecular-scale "clusters" (order of 1 nm in size) [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and, occasionally, mesoscale structures (order of 100 nm in size) [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] have been reported in such aqueous solutions.…”

Section: Introductionmentioning

confidence: 99%

Mesoscale inhomogeneities in aqueous solutions of small amphiphilic molecules

et al. 2013

View full text Add to dashboard Cite

Small amphiphilic molecules, also known as hydrotropes, are too small to form micelles in aqueous solutions. However, aqueous solutions of nonionic hydrotropes show the presence of a dynamic, loose, non-covalent clustering in the water-rich region, This clustering can be viewed as "micelle-like structural fluctuations". Although these fluctuations are short ranged (approximately 1 nm) and short lived (10 ps-50 ps), they may lead to thermodynamic anomalies. In addition, many experiments on aqueous solutions of hydrotropes show the occasional presence of mesoscale (approximately 100 nm) inhomogeneities. We have combined results obtained from molecular dynamics simulations, small-angle neutron scattering, and dynamic light-scattering experiments carried out on tertiary butyl alcohol (hydrotrope)-water solutions and on tertiary butyl alcohol-water-cyclohexane (hydrophobe) solutions to elucidate the nature and structure of these inhomogeneities. We have shown that stable mesoscale inhomogeneities occur in aqueous solutions of nonionic hydrotropes only when the solution contains a third, more hydrophobic, component. Moreover, these inhomogeneities exist in ternary systems only in the concentration range where structural fluctuations and thermodynamic anomalies are observed in the binary water-hydrotrope solutions. Addition of a hydrophobe seems to stabilize the water-hydrotrope structural fluctuations, and leads to the formation of larger (mesoscopic) droplets. The structure of these mesoscopic droplets is such that they have a hydrophobe-rich core, surrounded by a hydrogen-bonded shell of water and hydrotrope molecules. These droplets can be extremely long-lived, being stable for over a year. We refer to the phenomenon of formation of mesoscopic droplets in aqueous solutions of nonionic hydrotropes containing hydrophobes, as mesoscale solubilization. This phenomenon may represent a ubiquitous feature of nonionic hydrotropes that exhibit clustering in water, and may have important practical applications in areas, such as drug delivery, where the replacement of traditional surfactants may be necessary.

show abstract

The study of hydrophobicity in water–methanol and water–tert-butanol mixtures

Cited by 29 publications

References 28 publications

Volumetric behavior of water–methanol mixtures in the vicinity of the critical region

Volumetric behavior of water–methanol mixtures in the vicinity of the critical region

Structural, rheological and dynamic aspects of hydrogen-bonding molecular liquids: Aqueous solutions of hydrotropic tert-butyl alcohol

Mesoscale inhomogeneities in aqueous solutions of small amphiphilic molecules

Contact Info

Product

Resources

About