The heterogeneous associating behavior of the aqueous binary mixtures of ethyl alcohol, ethylene glycol, glycerol and mono alkyl ethers of ethylene glycol, and aqueous ternary mixtures of equi-molar binary systems (i.e., mono alkyl ethers of ethylene glycol with ethyl alcohol, ethylene glycol and glycerol) have been investigated over the entire concentration range using accurately measured dielectric constants at 25 ∘C. The concentration dependent values of the excess dielectric parameter εE and effective Kirkwood correlation factor geff were determined using the measured values of the static dielectric constant, εo, at 1 MHz and the high frequency limiting dielectric constant ε∞ = nD2. The observed εE values in aqueous binary and ternary mixtures are negative over the entire concentration range, which implies the formation of heterogeneous complexes between these molecules that reduces the effective number of dipoles. The stoichiometric ratio corresponding to the maximum interaction in alcohol + water mixtures increases with an increase in the number of hydroxyl groups of the alcohol molecules, but for mono alkyl ethers of ethylene glycol + water mixtures it decreases with the increase in the molecular size of the mono alkyl ethers. In aqueous ternary mixtures the stoichiometric ratio for the maximum extent of heterogeneous interaction is governed by the molecular size of the mono alkyl ethers. It was also found that the strength of the heterogeneous H–bond connectivities in the water + alcohol systems decrease with an increase in the number of hydroxyl groups of the alcohol molecules. However in the case of water + mono alkyl ether binary mixtures and in ternary mixtures, the strength of H–bond connectivities increases with the increase in the molecular size of the mono alkyl ether. An analysis of the geff values confirms that the heterogeneous interaction involves the orientation of molecular dipoles in the studied systems. 相似文献
The vapor–liquid equilibria of binary polymer–solvent systems was modeled using the Non-Random Hydrogen Bonding (NRHB) model. Mixtures of poly(ethylene glycol), poly(propylene glycol), poly(vinyl alcohol) and poly(vinyl acetate) with various solvents were investigated, while emphasis was put on hydrogen bonding systems, in which functional groups of the polymer chain can self-associate or cross-associate with the solvent molecules. Effort has been made to explicitly account for all hydrogen bonding interactions. The results reveal that the NRHB model offers a flexible approach to account for various self- or cross-associating interactions. In most cases model's predictions (using no binary interaction parameter kij = 0) and model's correlations (using one temperature independent binary interaction parameter, kij ≠ 0) are in satisfactory agreement with the experimental data, despite the complexity of the examined systems. 相似文献
The interfacial tension of the binary two-phase mixture of water and ethylene glycol isobutyl ether (EIB) was measured as a function of temperature in the vicinity of the lower critical solution temperatureTc under atmospheric pressure. The interfacial tension decreased with decreasing temperature and approached zero atTc. The thermodynamic quantities of interface formation were evaluated by applying equations developed previously to the interfacial tension vs temperature curves. The results were compared with those of the water and diethylene glycol diethyl ether system examined previously, and the effect of the molecular structure of the ether molecule on its interfacial behavior was discussed. It was suggested that the hydration of the ethylene oxide groups of ether molecules was an important factor in the interface formation as well as in the mixing of component molecules of the systems investigated here. 相似文献
The catalyst (N,N‐bis(2,6‐dibenzhydryl‐4‐ethoxyphenyl)butane‐2,3‐diimine)nickel dibromide, a late transition metal catalyst, was prepared and used in ethylene polymerization. The effects of reaction parameters such as polymerization temperature, co‐catalyst to catalyst molar ratio and monomer pressure on the polymerization were investigated. The α‐diimine nickel‐based catalyst was demonstrated to be thermally robust at a temperature as high as 90 °C. The highest activity of the catalyst (494 kg polyethylene (mol cat)?1 h?1) was obtained at [Al]/[Ni] = 600:1, temperature of 90 °C and pressure of 5 bar. In addition, the performance of a binary catalyst using nickel‐ and palladium‐based complexes was compared with that of the corresponding individual catalytic systems in ethylene polymerization. In a study of the catalyst systems, the average molecular weight and molecular weight distribution for the binary polymerization were between those for the individual catalytic polymerizations; however, the binary catalyst activity was lower than that of the two individual ones. The obtained polyethylenes had high molecular weights in the region of 105 g mol?1. Gel permeation chromatography analysis showed a narrow molecular weight distribution of 1.44 for the nickel‐based catalyst and 1.61 for the binary catalyst system. The branching density of the polyethylenes generated using the binary catalytic system (30 branches/1000 C) was lower than that generated using the nickel‐based catalyst (51/1000 C). X‐ray diffraction study of the polymer chains showed higher crystallinity with lower branching of the polymer obtained. Also Fourier transform infrared spectra confirmed that all obtained polymers were low‐density polyethylene. 相似文献
Micellar properties of binary combinations of a family of cationic alkyl triphenyl phosphonium bromides with varying chain
length (C10–C16) were investigated in aqueous and aqueous ethylene glycol mixtures employing conductometric technique. The results of the
mixed systems were analyzed in the light of the Regular Solution Theory and the Gibbs–Duhem equation to evaluate the composition
of the mixed micelle, the activity coefficients, and the interaction parameter (β). The excess free energy and the other related thermodynamic parameters of mixing were calculated and discussed in terms
of the stability of the mixed micelles in the presence of an ethylene glycol additive.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
The synthesis of ethylene glycol monoethyl ether acetate by esterification of ethylene glycol monoethyl ether with acetic acid is of industrial interest. The following experimental determinations were carried out: vapour—liquid equilibria of the binary systems acetic acid—ethylene glycol monoethyl ether acetate and acetic acid—ethylene glycol monoethyl ether; liquid—liquid equilibrium of the binary system water—ethylene glycol monoethyl ether acetate; solubility curves of the ternary systems water—ethylene glycol monoethyl ether acetate—ethylene glycol monoethyl ether and water—acetic acid—ethylene glycol monoethyl ether acetate.The parameters of a model able to describe the phase equilibria of the whole system have been identified. Liquid—liquid, as well as vapour—liquid equilibrium data, are satisfactorily correlated with an unique choice of parameters. 相似文献
The refractive index and excess molar volume, of the following short hydrocarbon chain co-surfactants were studied: ethylene
glycol, ethylene glycol monomethyl ether, ethanol, n-, i-propanol, acrylic acid, ethyl monomethylmaleate and acrylamide. The refractive indexes of the aqueous solutions of these
compounds vary nonlinearly with composition. The maximum variation of refractive indexes occurs up to a cosurfactant/water
molar ratio equal to 1 5. The fluorescence probe method was successfully used to evidence the structure modifications of the
alcohol–water mixtures. The intensity ratio of pyrene fluorescence vibrational bands varies nonlinearly with the composition
of the systems; in case of 1-propanol, the sudden decrease of the ratio is similar to that of micellar solutions, so that
a critical concentration of association can be determined at a 0.88 water mole fraction. It was shown, in good agreement with
data in literature, that the compounds mentioned penetrate into the cluster structure of water and associate. At concentrations
higher than critical, restructuring of aqueous solutions continues and structures of bicontinuous or w/o type may arise. The
excess volume of the first six compounds is negative owing to the restructuring just mentioned. Vinyl acetate may penetrate
in the struc-tures of binary systems to form homogeneous systems. The number of homogeneous systems decreases in the sequence:
ethanol, i-propanol, acrylic acid, n-propanol, the mono-methylether of ethyleneglycol, methyl monomaleate. The vinyl acetate over cosurfactant molar ratio of
limiting homogeneous systems varies in inverse sequence at the same monomer/water ratio. After radical polymerization of VAc
in homogeneous samples transparent systems were obtained only when the polymer was solubilized in cosurfactant water mixtures.
Received: 16 July 1996 Accepted: 14 January 1997 相似文献
In co[poly(ethylene terephthalate)-p-oxybenzoate] containing 30 mole % oxybenzoate units, the ethylene terephthate units crystallize. The copolymer melts in the temperature range 180–210°C to form a nematic phase which, at a higher temperature, transforms to an isotropic liquid. The latent heat of the first transition is 5 cal/g, and the thermodynamic melting temperature, 247°C, is essentially that expected for a random copolymer of this composition. The nematic → isotropic transition occurs at 244°C, with an enthalpy change of 3.2 cal/g (10% of the heat of fusion of poly(ethylene terephthalate)). We conclude that semiflexible polymers form a nematic phase which is rather highly disordered. The model of the nematic phase treated by Flory is modified to increase its entropy through incorporation of chain bends (which must be correlated in position and direction with those in neighboring molecules). This increases the chain extension, as measured by the fraction (1–f) of collinear chain bonds, required to form the nematic phase. For binary polymer-solvent systems, an appropriate scaling of f values leaves the phase diagram as predicted by Flory's treatment essentially unchanged. 相似文献
Viscosities, at T = 293.15, 298.15 and 303.15 K, in the binary mixtures of 2-ethoxyethanol with ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol have been measured as a function of composition. From the experimental data the deviations in the viscosity have been calculated. The viscosity data, at T = 298.15 K, were correlated with equations of Hind et al., Grunberg and Nissan, and Frenkel. The results are discussed in terms of intermolecular interactions and structural properties of studied binary mixtures. 相似文献
Solute-solvent and solvent-solvent interactions were investigated for binary mixtures of an ionic liquid (IL) 2-hydroxy ethylammonium
formate as with methanol, ethylene glycol and glycerol. The physicochemical properties of the solvent mixtures at 25 °C, over
the whole range of mole fractions, were determined using solvatochromic probes. High normal polarity (ETNE_{T}^{N}) in the alcohol-rich region confirms solute-solvent interactions in this medium. Dipolarity/polarizability (π∗) show a different trend to ETNE_{T}^{N} with a positive deviation from ideal behavior in IL-glycerol mixtures. However, these deviations for other solvent mixtures
are insignificant. Contrary to what is observed for ETNE_{T}^{N} and π∗, hydrogen-bond donor (HBD) acidity and hydrogen-bond acceptor (HBA) basicity demonstrate similar trends. The applicability
of the combined nearly-ideal binary solvent/Redlich-Kister (CNIBS/R-K) equation for the correlation of various parameters
provides a simple computational model to correlate and/or predict various solvatochromic parameters for many binary solvent
systems. 相似文献
A general gas-chromatographic method is proposed for determining mutual solubility of partially miscible organic solvents.
The method involves gradual increase of the concentration of one component in the other component in the region below their
mutual solubility limit, determining parameters of the linear regression c = aS + b (c is the concentration, and S is the peak area), analysis of saturated solutions of components of binary systems in each other (at S ≈ const), and calculating c values from the obtained equation. The method was tested by known data on mutual solubility of components of the hexane-acetonitrile
and hexane-nitromethane binary systems. Data for the hexane-2,2,2-trifluoroethanol and perfluorodecalin-acetonitrile binary
systems are obtained for the first time; in the latter case, abnormally low mutual solubility of components is revealed. 相似文献
Vapor–liquid equilibria (VLE) data of 2-butanol?+?benzene or toluene or o- or m- or p-xylene measured by static method at 308.15?±?0.01?K over the entire composition range are reported. The excess molar Gibbs free energies of mixing (GE) for these binary systems have been calculated from total vapor pressure data using Barker's method. The GE for these binary systems are also analyzed in terms of the Mecke–Kempter type of association model with a Flory contribution term using two interaction parameters and it has been found that this model describes well the GE values of binary systems benzene or toluene. 相似文献
Surface tension of two ternary mixtures of water/acetonitrile/methanol and water/acetonitrile/ethanol, and their constituent binaries, were measured over the whole range of composition at 298.15 K and ambient pressure. The experimental data were used to calculate in the surface tension deviations (Δσ). The negative values of Δσ for the binary and ternary systems indicate the strong hydrogen bonding between unlike molecules of mixtures (particularly in the high concentration of water). Surface tension data of the binary systems were correlated with Fu et al., Wang–Chen, Redlich–Kister and Myers–Scott models. The mean standard deviation obtained from the comparison of experimental and calculated surface tension values for binary systems with four models is less than 0.42. Finally, the concentration dependence of the surface tension deviation of the ternary mixtures at 298.15 K was correlated using Pando et al. and Ku et al. models, with satisfactory results. 相似文献
New hybrid composites based on mesostructured V2O5 containing intercalated poly(ethylene oxide), poly-o-methoxyaniline and poly(ethylene oxide)/poly-o-methoxyaniline were prepared. The results suggest that the polymers were intercalated into the layers of the mesostructured
V2O5. Electrochemical studies showed that the presence of both polymers in the mesostructured V2O5 (ternary hybrid) leads to an increase in total charge and stability after several cycles compared with binary hybrid composites.
This fact makes this material a potential component as cathode for lithium ion intercalation and further, a promising candidate
for applications in batteries. 相似文献
Applying different surface and spreading techniques to form binary monolayers in a different mixing state, the mixing behavior of the three binary systems cholesteryl formiate/stearic acid, cholesteryl acetate/stearic acid, and cholesteryl-n-propionate/stearic acid were investigated and compared.Analyzing the force ()/area (a) isotherms and the equilibrium spreading pressures (e of the binary monolayers, it can be concluded that the components of the three binary systems do not mix within the whole concentration range. The lipids in the binary monolayers are completely immiscible. 相似文献
In this paper, we report experimental densities, dynamic viscosities, and refractive indices and their derived properties of the ternary system (1-butyl-3-methylimidazolium methylsulphate + ethanol + water) at T = 298.15 K and of its binary systems 1-butyl-3-methylimidazolium methylsulphate with ethanol and with water at several temperatures T = (298.15, 313.15, 328.15) K. These physical properties have been measured over the whole composition range and at 0.1 MPa. Excess molar volumes, viscosity deviations, and excess free energy of activation for the binary systems at the abovementioned temperatures, were calculated and fitted to the Redlich–Kister equation to determine the fitting parameters and the root-mean-square deviations and for the ternary systems were calculated and fitted to Cibulka, Singh et al., and Nagata and Sakura equations. The ternary excess properties were predicted from binary contributions using geometrical solution models. Refractive indices were measured from T = 298.15 K over the whole composition range for the binary and ternary systems. The results were used to calculate deviations in the refractive index. 相似文献
Summary: Dendronized poly(methacrylate)‐poly(ethylene oxide) (PDMA58‐b‐PEO45) formed as a stoichiometric inclusion complex with α‐cyclodextrin. The incorporation of the rodlike PDMA blocks produced no apparent change in the crystal structure, but its steric hindrance on the PEO chain resulted in lower yield as compared with the pure PEO. Moreover, the architectural transition from rod–coil to rod–rod led to a morphological change from spindly aggregates to rods in a binary solvent mixture of N,N‐dimethylformamide and water.
Synthesis and self‐assembly of the α‐cyclodextrin‐[dendronized poly(methacrylate)‐poly(ethylene oxide)] (α‐CD‐PDMA‐PEO) polypseudorotaxane (PR). 相似文献
Abstract The mesophase electrostatic stabilization energy (E) has been examined by using the ionic continuous solid solution model for binary systems of sodium and potassium alkanoates with a common anion. It is found that E increases with a decrease in chain length of the alkanoate anion and that there is an inverse proportionality between E and the square of the mesophase bilayer spacing. The electrostatic stabilization factor is shown to be responsible for the formation of an ionic mesophase in binary acetate and propionate systems derived from two non-mesomorphic components. 相似文献