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1.
Effects of electrical percolation accompanying variations in overall surfactant concentration с have been studied by the example of micellar sodium dodecyl sulfate solutions. It has been found that, in the studied concentration range of 0.001–1.2 M, dependences of electrical conductivity K on c may exhibit at least three break points, with the dK/dc derivatives changing in the vicinities of these points. At two of these points, which are reliably identified and correspond to critical micelle concentrations (CMC1 and CMC2), they decrease. At the third concentration, lying between CMC1 and CMC2, the dK/dc derivative increases. A substantiated assumption has been put forward that this break point, at which the dK/dc derivative increases, results from the clustering of micelles and the appearance of channels with a higher specific conductivity, which is provided by the contribution from the electrical conductivity of the diffuse and dense parts of micelle electrical double layers, upon the formation of clusters. The ionic surfactant concentration that corresponds to the break point at which the dK/dc value increases has been denoted as the critical percolation concentration. 相似文献
2.
A series of PEO45-b-PtBA53-b-PS x (x = 42, 84, 165) triblock terpolymers were synthesized by the atom transfer radical polymerization and characterized by size exclusion chromatography and 1H NMR. Their self-assemblies were conducted by a two-step hierarchical self-assembly method and a one-step dialysis method and the self-assembly behaviors were investigated. The morphologies, sizes, and size distributions of micelles produced by the self-assembly were determined by transmission electron microscopy and dynamic light scattering. The secondary self-assembled structure of PEO45-b-PtBA53-b-PS x obtained by the two-step hierarchical self-assembly could be controlled by tuning the length of PS block, the core forming block. The micelles were uniform with diameters of 20–25 nm and their size distributions, except for that of PEO45-b-PtBA53-b-PS165, were narrow with particle size distribution indexes ranging from 0.014 to 0.246. The one-step dialysis of the triblock terpolymers produced vesicular micelles with distinct vesicle walls that exhibited similar thicknesses. The vesicles did not show significant aggregation. The size distribution of PEO45-b-PtBA53-b-PS42 vesicle was the narrowest with a particle size distribution index value of 0.135. The PEO45-b-PtBA53-b-PS165 vesicles tended to overlap with each other. 相似文献
3.
S. V. Chapyshev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(2):254-259
Fine structure levels in an external magnetic field and angular dependences of resonance magnetic fields on the direction of an external magnetic field were calculated for two axially symmetrical quintet dinitrenes with the zero-field splitting parameters D q = 0.260 cm?1, E q = 0.000 and D q = 0.243 cm?1, E q = 0.003 cm?1. The EPR spectra of such dinitrenes contained lines of only three xy transitions (xy 1, xy 2, and xy 4), two Δm s = ±2 transition lines between the W ?2 and W 0 sublevels, and three additional lines from noncanonically oriented molecules whose magnetic axis Z made an angle of 12°–16° or 52°–54° with an external magnetic field. 相似文献
4.
It is shown that for numerous sp-metals there exists no unified work function (W e) dependence of the potential of zero charge E q = 0 and the potential drop characterizing the metal lyophilic behavior Δ M Hg E chem) q = 0. The reason is that the metal work function is by no means the only factor affecting the value of E q = 0. The quantities E q = 0 and (Δ M Hg E chem) q = 0 depend also on the distance of the solvent dipoles’ closest approach to metal surfaces (d ms) in the absence of the metal-solvent chemisorption interaction. When the metal-solvent chemisorption interaction is involved, this distance affects the degree of overlapping of the metal’s acceptor levels and the upper occupied donor levels in the solvent molecules. To reliably investigate the effect of any of these factors on E q = 0, the other one should be fixed up. It is shown, by example of Ga-, Bi-Gaand Sn-Ga-electrodes, as well as Pb-Ga-, In-Ga-, and Cd-Ga-electrodes demonstrating very close values of the “electrochemical work function” that the metal-solvent chemisorption interaction becomes stronger with the decreasing of d ms. The influence of this factor is intensified with the increasing of the solvent’s donor number DN. The W e dependence of E q = 0 and (Δ M Hg E chem) q = 0 can be traced by example of metals with nearly equal d ms values, e.g., Tl-Ga, In-Ga, and Ga. In all studied solvents, the deviation of E q = 0 from W e increased in the series Tl-Ga < In-Ga < Ga, that is, with the increasing of the metal’s work function in vacuum. The effect is intensified with the increasing of the solvent’s DN. The obtained results agree with the concept of donor-acceptor nature of the metal-solvent chemisorption interaction. 相似文献
5.
T. G. Movchan A. A. Averin D. V. Baulin E. V. Plotnikova V. E. Baulin A. Yu. Tsivadze 《Colloid Journal》2018,80(5):501-512
Electronic absorption spectroscopy and fluorimetry have been employed to study the behavior of magnesium octa[(4′-benzo-15-crown-5)oxy]phthalocyaninate (Mg[(B15C5O)8Pc]) in aqueous micellar solutions of sodium dodecyl sulfate and hexadecyltriphenylphosphonium bromide. Conditions have been found for the existence of monomeric Mg[(B15C5O)8Pc] complex in surfactant solutions to provide the possibility of using mixed solutions of the complex and cationic surfactants (alkyltriphenylphosphonium bromides) for photodynamic therapy. In surfactant solutions with different concentrations of micelles (cm) and the complex (cp), the maximum amount of monomeric Mg[(B15C5O)8Pc] is achieved at cm/cp ≥ 4. 相似文献
6.
V. I. Smirnov V. G. Badelin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(9):1681-1684
the enthalpies of dissolution of glycine (Gly), glycylglycine (GlyGly), and glycylglycylglycine (GlyGlyGly) are measured in aqueous solutions of sodium dodecyl sulfate (SDS) at SDS concentrations m = 0–0.7 mol kg?1 and Т = 298.15 K by means of calorimetry. The obtained data are used to calculate the standard values of enthalpies of dissolution (Δsol H m ) and enthalpies of transfer (Δtr H m ) of glycine and its oligomers from water to SDS aqueous solutions. The dependences of Δsol H m and Δtr H m on SDS concentration in an aqueous solution at a constant concentration of glycine and its oligomers are determined. A comparative analysis of the thermodynamic characteristics of Gly, GlyGly, and GlyGlyGly transfer within the studied range of SDS concentrations is performed. The results are interpreted in terms of ion–ion, ion–polar, and hydrophobic interactions between SDS and molecules of glycine and its oligomers. 相似文献
7.
V. I. Smirnov V. G. Badelin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(5):900-904
Enthalpies of the dissolution of DL-α-alanylglycine (AlaGly), DL-α-alanyl-DL-α-alanine (AlaAla), DL-α-alanyl-DL-α-valine (AlaVal), and DL-α-alanyl-DL-norleucine (AlaNln) in an aqueous solution of sodium dodecyl sulfate (SDS) at SDS concentration of m = 0–0.07 mol kg?1 and temperature Т = 298.15 K are measured via calorimetry. The standard values of the enthalpy of dissolution (ΔsolH m ) and the transfer of dipeptides (ΔtrH m ) from water to aqueous SDS solutions are calculated using the experimental data. The dependences of ΔsolH m and ΔtrH m the SDS concentration at a constant concentration of dipeptide are established. Thermochemical characteristics of the transfer of AlaGly, AlaAla, AlaVal, and AlaNln in the investigated range of SDS concentrations are compared. The results are interpreted by considering ion–ion, ion–polar, and hydrophobic–hydrophobic interactions between SDS and dipeptide molecules. 相似文献
8.
Linear ABC triblock copolymer PtBA154-b-PS300-b-P2VP240 was successfully synthesized by RAFT polymerization. Block copolymer micelles were prepared by the two-step hierarchical self-assembly process. Size exclusion chromatography and 1H NMR were used to characterize the structure of samples. Morphologies and size of micelles were determined by transmission electron microscope. The results showed that the densely dispersed spherical micelles of PtBA154-b-PS300-b-P2VP240 were obtained in the first step of the hierarchical self-assembly process. In the second step, core-compartmentalized micelle strings with different lengths and distribution densities were obtained when the primary self-assembled solution was dialyzed in distilled water with pH ≈ 3. When distilled water with pH ≈ 3 was added drop-wise to this solution, uniformly dispersed spherical core-compartmentalized micelles of PtBA154-b-PS300-b-P2VP240 were prepared. Thus, hierarchical self-assembly structure of linear ABC triblock copolymer was obtained successfully and the preparation of uniformly dispersed spherical micelles of triblock copolymers was realized simply by changing the secondary self-assembly methods. 相似文献
9.
Structure and dynamics of a free aquaporin (AQP1) are studied by a coarse-grained Monte Carlo simulation as a function of temperature using a phenomenological potential with the input of a knowledge-based residue–residue interaction. Response of the radius of gyration (R g) of the protein to the temperature (T) is found to be nonlinear: Decay of R g at T ≤ T c is followed by a continuous increase at T ≥ T c before reaching its saturation. In thermo-responsive regime, the protein exhibits segmental globularization with the persistence of three regions along its sequence involving residues 1M–25V and 250V–269K toward the beginning and end segments with a narrow intermediate region around 155A–163D. A detail analysis of the structure factor S(q) shows a global random coil conformation at high temperatures with an effective dimension D e ~ 1.74 and a globular structure (D e ~ 3) at low temperatures. In thermo-responsive regime, the variation of S(q) with the wave vector q reveals a systematic redistribution of self-organizing residues (in globular and fibrous sections) that depends on the length scale and the temperature. 相似文献
10.
A novel two-dimensional network manganese(II) polymer complex [Mn(O2CCH2CI)2-(phen)] n has been synthesized and characterized by elemental analysis and IR spectrum. The crystal structure of title complex has also been determined, which is in monoclinic of a space group P21/c with the following unit cell parameters at 294K:a =1.9738 (4) nm,b=1.1384 (2) nm,c =0.74915(14) nm,V = 1.6795(5) nm3, Z= 2. 相似文献
11.
A. V. Kireiko I. A. Veselova T. N. Shekhovtsova 《Moscow University Chemistry Bulletin》2007,62(4):216-220
The properties of horseradish peroxidase in sodium dodecyl sulfate (DDS) reversed micelles in benzene-pentanol-water solutions are studied. The potential of the analytical application of direct and reversed DDS micelles is demonstrated using newly developed methods for the determination of peroxidase substrates (hydrogen peroxide and cystein), inhibitor (sulfanylamide), and activator (imidazole) via the oxidation of o-dianisidine (o-D) with hydrogen peroxide. 相似文献
12.
A. I. Klyndyuk 《Russian Journal of Inorganic Chemistry》2009,54(7):1014-1017
LnBaCuCoO5 + δ (Ln = Y, Dy) cuprocobaltites were prepared. Their unit cell parameters were determined and their thermal expansion, electrical conductivity (σ), and Seebeck coefficient (S) were studied in air in the range 300–1100 K. The compounds have tetragonal structures (space group P4/mmm). Their unit cell parameters are a = 0.3867(2) nm, c = 0.7550(7) nm, V = 112.9(2) × 10?3 nm3 for YBaCuCoO4.98; and a = 0.3872(2) nm, c = 0.7562(7) nm, V = 113.4(2) × 10?3 nm3 for DyBaCuCoO5.01. They are p-type semiconductors. The electrical conductivity of DyBaCuCoO5 + δ is slightly lower and its Seebeck coefficient is 1.5–2 times higher than the respective values for YBaCuCoO5 + δ apparently because of different electronic configurations of the rare-earth cations in LnBaCuCoO5 + δ (4d 0 for Y3+ and 4f 9 for Dy3+). Dilatometric measurements show that the LnBaCuCoO5 + δ phases in the range 300–1100 K do not experience structural phase transitions, and their linear thermal expansion coefficients (LTEC) are 14.3 × 10?6 K?1 for Ln = Y and 14.7 × 10?6 K?1 for Ln = Dy. 相似文献
13.
V. G. Badelin I. N. Mezhevoi E. Yu. Tyunina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(3):521-524
Calorimetric measurements of enthalpies of solution Δsol H m for glycine, L-cysteine, and glycylglycine in aqueous solutions of sodium dodecyl sulfate (SDS) with concentrations of up to 0.05 mol kg–1 are made. Standard enthalpy of solution Δsol H 0 and enthalpy of transfer Δtr H 0 of the dipeptide from water into mixed solvent are calculated. The calculated enthalpy coefficients of paired interactions of amino acids and dipeptide with SDS prove to be positive. Hydrophobic interactions between the biomolecules and SDS are found to have a major impact on the enthalpies of interaction in the three-component systems under study, within the indicated range of concentrations. 相似文献
14.
The present paper aims to study the proprieties of water confined in water/AOT/isooctane reverse micelles from their refractive indices at 298.5 K. The refractive indices of the microemulsions were investigated at increasing water concentration and at different micellar volume fractions, Φ d. The refractive index of micellar water was deduced for a large water to AOT molar ratio, W 0. The refractive index of interfacial water was also calculated. Then, the molar faction of interfacial water, α, was deduced for different W 0 values and compared with those measured by NMR as reported in the literature. The results show qualitative agreement. Finally, the average aggregation number, n agg, the area per surfactant headgroup, σ, as well as the interfacial thickness, d i, of the reverse micelles were determined for the W 0 values studied. The values of these structural parameters also show good qualitative agreement with NMR and small angle X-ray scattering data reported in the literature. Thus, the refractive index method can be a cheap and fast alternative for these two methods. 相似文献
15.
16.
K. V. Yusenko I. V. Korolkov S. A. Gromilov S. V. Korenev 《Journal of Structural Chemistry》2007,48(2):379-382
The crystal structure of [Os(NH3)5Cl][ReCl6] has been refined by X-ray powder analysis: a = 11.645(3) Å, b = 8.3788(2) Å, c = 15.277(4) Å, β = 91.029(6)°, V = 1490(1) Å3, d x = 3.163 g/cm3, space group P21/m, Z = 4. The thermolysis product of the salt in a hydrogen atmosphere is a solid substitution solution Os0.5Re0.5: a = 2.753(2) Å, c = 4.366(3) Å, space group P63/mmc; coherent scattering region (CSR) is ~230 Å. 相似文献
17.
M. L. Kovba Yu. Ya. Skolis A. M. Abakumov J. Hadermann I. S. Sukhushina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(12):2033-2038
The existence of the [SrF0.8O0.1]2.5[Mn6O12] = Sr2.5Mn6O12.5 ? δF2 compound was established in the SrO-Mn2O3-SrF2 system at 900°C and p(O2) = 1 atm. The crystal structure of strontium fluoromanganite was determined from the X-ray powder diffraction data, electron diffraction, and high-resolution electron microscopy. It can be described in the monoclynic system with four Miller hklm indices: hklm: H = h a* + k b* + l c 1 * + m q 1, q 1, q 1 = c 2 * = γc 1 * , γ ≈ 0.632, a ≈ a ≈ 9.72 Å, b ≈ 9.55 Å, c 1 ≈ 2.84 Å, c 2 ≈ 4.49 Å, monoclinic angle γ ≈ 95.6°. The electromotive force method with a solid fluorine ion electrolyte was used to refine the composition of fluoromanganite and determine the thermodynamic functions of its formation from phases neighboring in the phase diagram (SrMn3O6, Mn2O3, SrF2, and oxygen), ΔG°, kJ/mol = ?(111.7 ± 1.9) + (89.5 ± 1.5) × 10?3 T. 相似文献
18.
Physicochemical properties of aqueous solutions of binary mixtures of lignosulfonates and sodium dodecyl sulfate were studied. Introduction of sodium dodecyl sulfate into solutions of high-molecular-mass lignosulfonates at certain ratios causes macrophase separation of the systems with the formation of loose precipitates. A synergistic effect of a decrease in the surface tension is observed in the mixed solutions. This effect increases with increasing lignosulfonate molecular mass and temperature. The revealed relationships are caused by hydrophobic interactions of hydrocarbon radicals of sodium dodecyl sulfate with hydrophobic segments of lignosulfonate polymer chains with the formation of micellar associates. Aqueous solutions of binary mixtures of lignosulfonates (сLS ≥ 0.2 g dm–3) and sodium dodecyl sulfate (сDSNa ≥ 0.08 g dm–3) can be recommended for use as surfactant formulations for high-temperature autoclave leaching of polymetal ores. 相似文献
19.
Micellar preconcentration has been proposed to improve the procedure of spectrophotometric determination of sodium dodecyl sulfate (SDS). It involves quantitative extraction by reversed micelles of Triton N-42 in n-decane and the subsequent formation of an ion associate with methylene blue and azure A upon destruction of the micellar solution by diluting it with a mixture of chloroform and n-decane in the presence of small concentrations of a dye solution. The absence of losses of 10?7?10?5 M SDS upon from 5-to 50-fold preconcentration is confirmed by the standard addition method (RSD = 4–5%); the determination limit of SDS equals 5 × 10?8 M. 相似文献
20.
I. A. Bardina O. S. Zhukova N. V. Koroleva N. Samadani-Langerudi S. N. Lanin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(3):479-482
The adsorption properties of γ-Al2O3 were studied using gas chromatography. Isotherms of adsorption of n-alkanes (C6–C9), hex-1-ene, benzene, and isobutanol were measured within 70–100°C. The isosteric heats of adsorption and contributions to them from dispersion (Δq dis) and specific (Δq sp) interactions were determined for hex-1-ene, benzene, and isobutanol. Under the conditions covered, hex-1-ene molecules are adsorbed mainly on account of dispersion interactions. For the adsorption of benzene, Δq dis is nearly twice as large as Δq sp, while for the adsorption of isobutanol, Δq sp is nearly twice as large as Δq dis. At 100°C, isobutyl alcohol is chemisorbed. 相似文献