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Variation of the mean force potential W A (without numerical values) and
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The results of previous studies of the increments \(
\Delta G_{CH_2 }^0
\), \(
\Delta H_{CH_2 }^0
\), and \(
T\Delta S_{CH_2 }^0
\) in hydrocarbon solution processes in water, evaporation, hydration, and transfer from vapor and water to surfactant micelles are summarized. The corresponding thermodynamic cycles were constructed. A micelle was shown...
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Citations
... in the processes of hydrocarbon solution in water, evaporation, hydration, transport from steam and water into micelles of SAS were constructed [14]. It appeared that in the process of transport of СН 2 group from water in micelles in the systems of n-hydrocarbons-dodecyl sulfate, 7 . ...
The authors generalize the research aimed at integrated production of nanomaterials. Mixes of metal ions are concentrated and separated in ion flotation. In micellar solutions of extracted ions, nanoparticles of metals or their oxides are obtained. Nanoparticles are converted in nanomaterials. The article discusses physico-technical problems of ion flotation, production of nanoparticles in direct micelles and properties of nanomaterials.
... The function log(x 2 )(n) for gaseous hydrocarbons C1−C4 has another slope in comparison with liquid hydrocarbons because there is transfer of molecules from gas to water. This process is accompanied by an unfavorable change in increment 26 Figure 1). According to our concept, hydrocarbons and hydrotrops are placed in the structure of LDL, shifting the balance in its direction. ...
... The net or water-separated hydrophobic interaction includes the association of methylene groups when they are separated by at least one layer of water molecules. 26 This process may occur if methylene groups change their state from hydrophobic hydration (ΔG CH 2 0 = +0.7 kJ mol −1 ) to the state when water surrounding the methylene groups changes its structure (ΔG CH 2 0 = −0.7 kJ mol −1 ) by LLPT. Taking into account the energy parameters of this process (ΔH CH 2 0 = 5.8 kJ mol −1 and TΔS CH 2 0 = 7.2 kJ mol −1 ), it is possible to speak about the weakening of H-bonds and the increasing entropy of water without any contribution of the dispersion interaction. ...
... increment of the standard Gibbs energy of micellization (Figure 2).26 Water does not increase the intermolecular interaction of methylene groups of surfactants in the micelle in comparison to the dispersion interaction in the liquid hydrocarbon. ...
Polyamorphous transitions in supercooled water, porous substances, solutions of polyols and proteins are studied intensively. They accompany self-organization of hydrocarbons and surfactants. In this study, the methods of polyamorphous transitions identification are proposed, their dependence on hydrocarbons and surfactants concentration and sizes is investigated. The place of polyamorphous transitions in the general theory of phase separation is determined, their bistability, self-oscillations, hysteresis, fluctuations, cooperative effect, enthalpy, entropy are described. Surface, volume and diffusion instabilities of polyamorphous transitions are analyzed. Technologies based on the properties of polyamorphous transitions are proposed.
... Micelle for mation with an increase in the concentration of amphiphiles occurs abruptly due to one property of a solution, and smoothly due to another. It is char acterized by two relaxation times and the solubiliza tion Gibbs energies of each methylene group [5]. These features of micelle formation can be explained by LL transitions. ...
... The con tribution from the entropy of water is considered in the thermodynamics of micelle formation accord ing to existing models. Nevertheless, in only a few studies has the LL transition been used to solve problems of micelle formation [1,5,12,13], due to the lack of experimental data on two liquid phases that differ in structure and by the problems of iden tifying LL transitions. It was recently found that clusters of low (LDL) and high (HLD) density exist in water on a ≈1 nm scale [14]. ...
... We showed in [5] that the LL transition formed two different micelle structures of C7-C12 amphiphiles: a contact structure ( = ⎯ 3.7 kJ/mol) and a hydrated structure ( = ⎯ 1.4 kJ/mol) where is the increment of the standard Gibbs energy of micelle formation. Water does not increase the intermolecular interaction between the surfactant methylene groups in a micelle, relative to the dispersive interaction in liq uid hydrocarbon. ...
A way of identifying polymorphic transitions via the hydrolysis of S-decylisothiuronium chloride and other properties of water in solutions of amphiphiles is described. Features of amphiphile transitions (smoothness, micelle bistability, solubilization hysteresis, the autooscillation of micelles, and fluctuations in the extensive properties of a water and micelle nanosystem ensemble) are discussed.
... These properties are closely related to the structure of micellar aggregates. Different models can be applied to describe the structure: phase model, model of mass action, model of multiple equilibriums [1], and dualistic model [2,3]. So, within the limits of the dualistic model, surfactant micelles can co-exist in two states: contact and hydrated ones. ...
... In the contact state, surfactant hydrocarbon groups are in contact, and in the hydrated state, they are separated from each other by at least one water molecule. The dynamics of the dualistic structure of micelles has been investigated by a thermodynamic method [3]. It is of interest to analyze this structure of micelles by a spectroscopic, in particular 13 ɋ NMR, method because it is capable of detecting fast relaxation processes. ...
... The increment 0 ma G ' (-1.8 kJ/mol) per one methylene group agrees well with the increment for a hydrate associate (-1.4 kJ/mol) found based on a thermodynamic analysis of the micelle formation process of sodium alkylsulphates [2,3]. ...
13C NMR chemical shifts are obtained for aqueous solutions of alkylammonium chlorides (C6–C9) in the region of the critical micelle concentration (CMC). A new method of processing 13C NMR experimental data for aqueous solutions of alkylammonium chlorides is developed to calculate the aggregation numbers
N of micelles and the equilibrium constants K of the micelle formation within the law of mass action. With the use of these N and K values the standard Gibbs energy of the micelle formation and its increment of −1.8 kJ/mol are found for the methylene group.
A small increment confirms the hypothesis about the structure of micelles consisting of both contact and hydrated associates.
The structural model of the association of alkylammonium chlorides in water, the effect of alkyl chain length on the CMC,
the hydrophobic interaction, the formation of hydrate associates, and also a possible classification of surfactants based
on this are discussed.
Keywords
13C NMR–alkylammonium chlorides–structure of micelles in water–structural model of association
... It was previously demonstrated [6] that the LL phase transition forms two different micellar struc tures for C7-C12 amphiphiles: (i) contact structure (Δ = -3.7 kJ/mol) and (ii) hydrated structure (Δ = -1.4 kJ/mol). ...
Phase transitions in ensembles of water clusters in aqueous solutions of C11–C28 n-hydrocarbons and C2–C12 amphiphiles have been studied as dependent on the concentration and size of dissolved molecules.
A critical size (approximately corresponding to the volume of undecane molecule) for water clusters is determined, which triggers
the phase transition that leads to the formation of bistable amphiphile micelles.
... of micelle formation of surfactants is -3.0 kJ mol 2 0 CH G -1 ; solubilization of n-hydrocarbons is -3.7 kJ mol -1 for contact micelles and -1.4 kJ mol -1 for hydrated ones [11]. The negative sign at the increment was adopted in accordance with the increase in the solubility of 2 0 CH G 12 -C 18 alkanes compared with the behavior of 5 -C 9 alkanes with N C = 12-18. ...
... As can be seen in Fig. 2 alkane. The thermodynamic cycle is identical to that of a hydration hydrophobic interaction of a surfactant [11]. ...
Thermodynamic cycles including the increments \( \Delta G_{CH_2 }^0 , \Delta H_{CH_2 }^0 \), and \( T\Delta S_{CH_2 }^0 \) were constructed for dissolution, evaporation, hydrophobic hydration of C5–C9 hydrocarbons, and transfer from vapor (\( \Delta G_{CH_2 }^0 \) = −0.7 kJ·mol−1, \( \Delta H_{CH_2 }^0 \) = 2.9 kJ·mol−1, \( T\Delta S_{CH_2 }^0 \) = 3.6 kJ·mol−1) and water (\( \Delta G_{CH_2 }^0 \) = −1.4 kJ·mol−1, \( \Delta H_{CH_2 }^0 \) = 5.8 kJ·mol−1, \( T\Delta S_{CH_2 }^0 \) = 7.2 kJ·mol−1) to micelles of C12–C18 hydrocarbons. The formation of bistable hydrated micelles of C12–C18 is explained by a transition between the order-disorder states in an assembly of small (nano) systems of water. The extensive parameters of small systems and critical phenomena predicted by fluctuation theory are discussed.
Aqueous surfactant solutions exhibit self-organization and coexistence of low-density (LDL) and high-density (HDL) water clusters (fluctuations), as well as self-oscillations between these extremes. This work shows that HDL and LDL can be interpreted, respectively, as quantum and classical ensembles of harmonic oscillators in their ground states, which continuously oscillate between these states, creating a temporal phase as a result of a quantum-thermal quantum transition. They have unexpected properties, which we call emergent. Surfactant substances (a set of surfactant molecules) undergo a classical (thermal) phase transition such as solid phase/liquid phase melting. Water undergoes a classic (thermal) ice/water phase transition. Aqueous micellar solutions undergo a quantum-thermal phase transition that is not inherent in its components taken individually.
Aqueous micellar solutions of sodium dodecyl sulphate (SDS) were investigated using X-ray scattering technique in the concentration range 0.008–0.1 M and analyzed by a model-independent approach. The obtained diameter of the spherical micelle (6.0 nm) with concentration 0.01 M is greater than that analyzed by direct modeling and by small-angle neutron scattering (4.4 nm). In the study of SDS solution of 0.01 M concentration by dynamic light scattering method, the following three hydrodynamic spheres were identified: SDS dimers and two micelles with water. The diffusion rate of these spheres decreases with the increase of their size. When adding 0.01 M of NaCl the dimers disappear, and the hydrodynamic spheres with diameter 3.14 nm appear. The results are discussed in the framework of the concept of polyamorphous transition between ensembles of water clusters of low and high density levels. Polyamorphous transition accompanies the formation of dual structures of contact and separated by water micelles with different rates of diffusion.
Using the aggregation numbers of micelles and the effective sizes of hydrated surfactant ions and counterions of the first coordination sphere, we calculated the average geometric characteristics of the surface layer of ionic spherical micelles in solutions of the sodium n-alkyl sulfate homologues with nC = 8, 10, 12, and 14 carbon atoms in the molecule; in particular, we established 1) the size of the micelle core; 2) the thickness of the electrical double layer on the surface; 3) the mutual arrangement parameters of hydrophilic and hydrophobic ions; 4) the number of “free” water molecules and showed their dependence on the homologue number and the degree of binding of counterions.
