GC Investigation of the Solubility Parameters of Water-Soluble Homopolymers and Double-Hydrophilic Diblock Copolymers

Solubility parameters of water-soluble 2-(diethylamino)ethyl methacrylate (DEA) homopolymer and [2-(diethylamino)ethyl methacrylate]-[2-(dimethylamino) ethyl methacrylate] (DEA–DMA) diblock copolymer were analyzed by inverse gas chromatography and values were compared to the solubility parameters of 2-(dimethylamino) ethyl methacrylate (DMA) homopolymer. Sorption thermodynamic parameters of some aliphatic, alicyclic and aromatic hydrocarbons, weight fraction activity coefficients, Flory–Huggins interaction parameters and solubility parameters for both hydrocarbons and polymers were calculated. It was observed that sorption thermodynamic parameters on (co)polymers depend on the molecular structures of hydrocarbons. Evaluating both the calculated values of the weight fraction activity coefficients and Flory–Huggins interaction parameters, the solving ability of the hydrocarbons for DEA, DMA homopolymers and DEA–DMA diblock copolymer decreased in the following sequence: aromatic > alicyclic > aliphatic hydrocarbons.     

Effect of temperature on the (liquid + liquid) equilibrium for aqueous solution of nonionic surfactant and salt: Experimental and modeling

The effect of temperature on the (liquid + liquid) equilibrium of the aqueous solution of surfactant polyoxyethylene cetylether (with abbreviation name Brij 58) and diammonium hydrogen phosphate has been investigated at T = (303.15, 313.15, 323.15, and 333.15) K. The Flory–Huggins equation with two electrostatic terms (Debye–Huckle and Pitzer–Debye–Huckle equations) was used to correlate the phase behavior of this system. Good agreement has been found between experimental and calculated data from both models. The results indicated that the enlargement of the two-phase region upon increasing the temperature. Additionally temperature dependency of the parameters of the Flory–Huggins model has been calculated.     

Quaternary (liquid + liquid) equilibria of aqueous two-phase poly (ethylene glycol), poly (DMAM–TBAM), and KH2PO4: Experimental and generalized Flory–Huggins theory

Quaternary (liquid + liquid) equilibrium (LLE) data of the aqueous two-phase poly (ethylene glycol), poly (N,N-dimethylacrylamide-t-butylacrylamide) with abbreviation name poly (DMAM–TBAM) as a hydrophobic association water-soluble copolymer and KH₂PO₄ has been determined experimentally at T = 338.15 K. Furthermore, the generalized Flory–Huggins theory with two electrostatic terms (the Debye–Hückel and Pitzer–Debye–Hückel) was used for correlation of the phase behavior of the quaternary system and the interaction parameters between all species were calculated.It was found that addition of poly (DMAM–TBAM) copolymer as well as changing the temperature can shift the binodal curves of aqueous two-phase systems containing polyethylene glycol (PEG) and salt. Also, the phase behavior of the DMAM–TBAM copolymer with some salts containing sodium chloride, ammonium hydrogen phosphate, potassium hydrogen phosphate, and sodium carbonate were studied experimentally at T = 338.15 K and the effect of the salt type on the their binodal curves was determined.     

(Surfactant + polymer) interaction parameter studied by (liquid + liquid) equilibrium data of quaternary aqueous solution containing surfactant,polymer, and salt

(Liquid + liquid) equilibrium (LLE) data of quaternary aqueous system containing polyoxyethylene (20) cetyl ether (with abbreviation name Brij 58, non-ionic surfactant), diammonium hydrogen phosphate, and poly ethylene glycol (PEG) with three molar masses {M_W = (1000, 6000, and 35,000) g · mol^?1} have been determined experimentally at T = 313.15 K.Furthermore, the Flory–Huggins theory with two electrostatic terms (Debye–Hückel and Pitzer–Debye–Hückel equations) have been used to calculate the phase behavior of the quaternary systems and (surfactant + polymer) interaction parameter as well as interaction parameters between other species. Temperature dependency of the parameters of the Flory–Huggins theory has been obtained.Also an effort have been done to show that addition of PEG as well as increasing the temperature can shift the binodal curves of the ternary aqueous system containing surfactant and salt to lower mole fraction of salt. Also the effect of polymer molar mass on the binodal diagram displacement has been discussed.     

A study of the surface analysis of some water‐soluble polymers by inverse gas chromatography

The surface characterization of 2‐(dimethylamino)ethylmethacrylate (DMA) and 2‐(N‐morpholino)ethylmethacrylate (MEMA) homopolymers and DMA–MEMA diblock copolymer was studied using inverse‐gas chromatography (IGC). The analyzed surface properties of (co)polymers were the dispersive component of the surface energy ( ) and the acid–base characters of (co)polymer surfaces. The specific free energy (ΔG^sp), enthalpy (ΔH^sp), and entropy (ΔS^sp) of adsorption of polar probes on (co)polymers were calculated. The values of ΔH^sp were correlated with both the donor and the modified acceptor numbers (AN) of the probes to quantify the acidic K_A and the basic K_D parameters of (co)polymer surfaces. The values obtained for the K_A and K_D parameters indicated basic characters for the surface of (co)polymers. The dispersive component values of the surface energy and the acid–base surface parameters of the DMA–MEMA diblock copolymer surface were found to be between those homopolymers as expected. Copyright © 2008 John Wiley & Sons, Ltd.     

Quaternary (liquid + liquid) equilibria of aqueous two-phase polyethylene glycol,poly-N-vinylcaprolactam,and KH2PO4: Experimental and the generalized Flory–Huggins theory

A quaternary (liquid + liquid) equilibrium study was performed to focus attention on the interaction parameters between poly-N-vinylcaprolactam (PVCL) and poly-ethylene glycol (PEG) as well as between other species. At first, the new experimental data of (liquid + liquid) equilibria for aqueous two-phase systems containing PEG, KH₂PO₄, and PVCL at T = 303.15 K have been determined. Then the Flory–Huggins theory with two electrostatic terms (the Debye–Huckel and the Pitzer–Debye–Huckel equations) has been generalized to correlate the phase behavior of the quaternary system. Good agreement has been found between experimental and calculated data from both models especially from the Pitzer–Debye–Huckel equation.Also an effort was done to compare the effect of temperature as well as addition of PVCL on the binodal curves of PEG, KH₂PO₄, and water. The effect of the type of salt on the binodals has been also studied, and the salting out power of the salts has been determined.     

Measurement and calculation of phase equilibria in the system n-pentane + poly(dimethylsiloxane) at 308.15–423.15 K

Vapor–liquid phase equilibria in the binary system n-pentane+poly(dimethylsiloxane) (PDMS) have been investigated experimentally at temperatures ranging from 308.15 to 423.15 K. The experiments have been performed at pentane mass fractions in the liquid phase ranging from 0 to 80% using the static method. PDMS with average molecular weights of 26 500 g/mol and 103 000 g/mol has been used. The data are in good agreement with several literature data by other researchers, mostly obtained by the use of inverse gas chromatography. The experimental data could be correlated well using the Flory–Huggins activity coefficient model for the polymer phase and the Peng–Robinson equation of state for the gas phase. Using statistical associating fluid theory (SAFT), it was only possible to reproduce the experimentally determined equilibria after adjusting the pure-component parameters of the polymer to the binary equilibria.Further, experimental data have been obtained for the R22 (difluorochloromethane)+PDMS system at 298.15 and 343.15 K.     

Phase equilibrium in aqueous two-phase systems containing ethylene oxide–propylene oxide block copolymers and dextran

Phase equilibrium of aqueous two-phase systems containing the polysaccharide dextran and ethylene oxide (EO)/propylene oxide (PO) triblock copolymers was investigated in this work. Phase diagrams at 25.0 °C were experimentally obtained for systems formed by either dextran 19 (average molar mass of 8200 g mol⁻¹) or dextran 400 (average molar mass of 236 kg mol⁻¹) and one of the following block copolymers F38, F68, F108, P105 and P103, which present different structures in terms of EO/PO ratios and molar masses. It was possible to assess the influence of the polymer features on the phase equilibrium: the main factors affecting phase equilibrium being the size of dextran molecule and the structure (mainly the EO/PO ratio) of the copolymer. The Flory–Huggins equation was used to correlate the experimental data with good qualitative agreement, allowing the inference that changes in the copolymer hydrophobicity are the main responsible for the observed phase diagrams.     

Solubility of hyperbranched polymer,Boltorn W-3000, in alcohols,ethers and hydrocarbons

(Solid/liquid + liquid) phase diagrams at ambient pressure have been determined for the hyperbranched polymer, Boltorn W3000 with alcohols (methanol, ethanol, 1-propanol, 1-hexanol, 1-decanol), or with ethers (tert-butyl methyl ether, tert-butyl ethyl ether), or with hydrocarbons (n-hexane, n-heptane, benzene, toluene) by a dynamic method from T = 240 K to the boiling temperature of the solvent. (Solid + liquid) phase equilibria with immiscibility in the liquid phase were detected for B-W3000 with the alcohols and aliphatic hydrocarbons. The upper critical solution temperatures, UCSTs, were measured for (B-W3000 + 1-hexanol and 1-decanol) systems. The experimental results of (solid + liquid) phase equilibria have been correlated using NRTL equation.     

(Liquid + liquid) equilibria in the binary systems (aliphatic,or aromatic hydrocarbons + 1-ethyl-3-methylimidazolium ethylsulfate,or 1-butyl-3-methylimidazolium methylsulfate ionic liquids)

(Liquid + liquid) equilibria of 14 binary systems composed of n-hexane, n-heptane, benzene, toluene, o-xylene, m-xylene, or p-xylene and 1-ethyl-3-methylimidazolium ethylsulfate, [emim]EtSO₄, or 1-butyl-3-methylimidazolium methylsulfate, [bmim]MeSO₄, ionic liquids have been done in the temperature range from (293.2 to 333.2) K. The solubility of aliphatic is less than those of the aromatic hydrocarbons. In particular, the solubility of hydrocarbons in both ionic liquids increases with the temperature in the order n-heptane < n-hexane < m-xylene < p-xylene < o-xylene < toluene < benzene. Considering the high solubility of aromatics and the low solubility of aliphatic hydrocarbons as well as totally immiscibility of the ionic liquids in all hydrocarbons, these new green solvents may be used as potentials extracting solvents for the separation of aromatic and aliphatic hydrocarbons.     

Isothermal (vapour + liquid) equilibrium (VLE) for binary mixtures containing diethyl carbonate,phenyl acetate,diphenyl carbonate,or ethyl acetate

The isothermal (vapour + liquid) equilibrium (VLE) (P–T–x_i–y_i) was determined the binary systems of (ethyl acetate + diethyl carbonate) from T = (373.2 to 453.2) K, (ethyl acetate + phenyl acetate) at T = 373.2 K, and (diethyl carbonate + phenyl acetate) at T = 373.2 K, while the VLE (P–T–x_i) of three diphenyl carbonate-containing binary systems was also determined experimentally at temperatures from (373.2 to 453.2) K. The experimental results show no azeotrope formation and near ideal solution behaviour for each binary system. These new VLE (P–T–x_i–y_i) data have been passed by the point, area, and infinite dilution thermodynamic consistency tests. The Wilson-HOC, the NRTL-HOC, and the UNIQUAC-HOC models were applied to correlate the VLE results and the optimal values of the model parameters have been determined through data reduction. Comparable results were obtained from these three models.     

Cloud-point measurements of the {H2O + poly(ethylene glycol) + NaNO3} system

The cloud-point (CP) temperatures and phase separation of {H₂O + poly(ethylene glycol) + NaNO₃} ternary system is studied by the turbidimetry method using a reaction calorimeter. The phase separation was also observed by visual inspection. Differences between the CP measured using the turbidimetry method and visual inspection, was up ±0.5 K. The Flory–Huggins model with a temperature and concentration-dependent interaction parameter was employed to correlate the phase diagram of the system. As a result of the correlation an average absolute deviation of 0.002 is obtained.     

Modeling the phase behavior of commercial biodegradable polymers and copolymer in supercritical fluids

Biodegradable polymers have received much attention as materials for reducing environmental problems caused by conventional plastic wastes. In this work, the thermodynamic behavior of binary and ternary systems composed by commercial biodegradable polymers and high-pressure fluids [poly(d,l-lactide) + dimethyl ether, poly(d,l-lactide) + carbon dioxide, poly(d,l-lactide) + chlorodifluoromethane, poly(d,l-lactide) + difluoromethane, poly(d,l-lactide) + trifluoromethane, poly(d,l-lactide) + 1,1,1,2-tetrafluoroethane, poly(butylene succinate) + carbon dioxide and poly(d,l-lactide) + dimethyl ether + carbon dioxide] and binary systems formed by commercial biodegradable copolymers and supercritical fluids [poly(butylene succinate-co-butylene adipate) + carbon dioxide] were studied. The Perturbed Chain-SAFT (PC-SAFT) and the Sanchez–Lacombe (SL) non-cubic EoS were used to model the liquid–fluid equilibrium (LFE) for these binary systems, by fitting one temperature-dependent binary interaction parameter. For comparison, the same data were also modeled by using the traditional Peng–Robinson (PR) cubic EoS. The three pure-component parameters of PC-SAFT and SL EoS and two pure-component of PR EoS were regressed by fitting pure-component data (liquid pressure–volume–temperature data for polymers and copolymer and vapor pressure and saturated liquid molar volume for fluids). The estimation of pure-component and binary interaction parameters was performed by using the modified maximum likelihood method with an objective function that includes the cloud point pressure. An excellent agreement was obtained with the PC-SAFT EoS, while the performance of the SL and PR EoS was less satisfactory.     

Phase equilibria study of the (N-octylisoquinolinium thiocyanate ionic liquid + aliphatic and aromatic hydrocarbon,or thiophene) binary systems

Binary liquid + liquid phase equilibria for 8 systems containing N-octylisoquinolinium thiocyanate, [C₈iQuin][SCN] and aliphatic hydrocarbon (n-hexane, n-heptane), cyclohexane, aromatic hydrocarbon (benzene, toluene, ethylbenzene, n-propylbenzene) and thiophene have been determined using dynamic method. The experiment was carried out from room temperature to the boiling-point of the solvent at atmospheric pressure. For the tested binary systems the mutual immiscibility with an upper critical solution temperature (UCST) for {IL + aliphatic hydrocarbon, or thiophene} were observed. The immiscibility gap with lower critical solution temperature (LCST) for the {IL + aromatic hydrocarbon} were determined. The parameters of the LLE correlation equation for the tested binary systems have been derived using NRTL equation. The phase equilibria diagrams presented in this paper are compared with literature data for the corresponding ionic liquids with N-alkylisoquinolinium, or N-alkylquinolinium cation and with thiocyanate – based ionic liquids. The influence of the ionic liquid structure on mutual solubility with aliphatic and aromatic hydrocarbons and thiophene is discussed.     

Separation of toluene from cyclic hydrocarbons using 1-butyl-3-methylimidazolium methylsulfate ionic liquid at T = 298.15 K and atmospheric pressure

In this paper the extraction of toluene from cyclic hydrocarbons (cyclohexane, or methylcyclohexane, or cyclooctane, or cyclohexene) was analyzed by liquid extraction with 1-butyl-3-methylimidazolium methylsulfate ionic liquid, [BMim][MSO₄], as solvent. The experimental (liquid + liquid) equilibrium (LLE) data were determined at T = 298.15 K and atmospheric pressure. Solubility curves were obtained by the cloud point method and tie-line compositions were determined by density measurement. An analysis of the influence of different cyclic hydrocarbons on the extraction was performed.The effectiveness of the extraction of toluene from cyclic hydrocarbons was evaluated by means of the solute distribution ratio and selectivity values. The degree of consistency of the experimental LLE data was ascertained using the Othmer–Tobias and Hand equations. The experimental data for the (liquid + liquid) equilibria of the ternary systems were correlated with the Non-Random Two-Liquid (NRTL) and UNIversal QUAsi-Chemical (UNIQUAC) thermodynamic models.     

The excess molar enthalpies and volumes of (N-methyl-2-pyrrolidinone + an alkan-1-ol) at T=298.15 K

The excess molar enthalpies H_m^E, for the mixtures (N-methyl-2-pyrrolidinone + ethanol, or pentan-1-ol, or hexan-1-ol, or heptan-1-ol, or octan-1-ol, or nonal-1-ol, or decan-1-ol, or undecan-1-ol) at T=298.15 K and atmospheric pressure have been obtained using flow calorimetry. Excess molar volumes at T=298.15 K and atmospheric pressure have also been determined for (N-methyl-2-pyrrolidinone + nonal-1-ol, or decan-1-ol, or undecan-1-ol) from density measurements using a vibrating tube densimeter. The experimental results have been correlated and compared with the results from the Flory–Benson–Treszczanowicz (FBT) theory and from the Extended Real Associated Solution (ERAS) model. The ERAS model accounts free volume effects according to the Flory–Patterson model and additionally association effects between the molecules involved. For the mixtures studied here the association effects arise from the self association of an alkan-1-ol molecules and also the cross-association of the proton of the alkan-1-ol with carbonyl oxygen of N-methyl-2-pyrrolidinone (NMP) molecule. The parameters adjusted to the mixtures properties are two cross-association parameters and the interaction parameter responsible for the exchange energy of the van der Waals interactions. Self-association parameters of the alcohols and NMP are taken from the literature.     

Kinetics of the alkaline hydrolysis of isatin and N-methylisatin in water and water-N,N-dimethylacetamide mixtures

The kinetics of amide bond cleavage of isatin and N-methylisatin in the presence of N,N-dimethylacetamide (DMA) was followed spectrophotometrically in the range of solvent composition (0–48.53 wt.%) and temperatures (40–70 °C) using piperidine as a nucleophile. The reaction was studied under pseudo-first-order kinetics. The rate of the reaction decreases largely with increasing organic solvent content. The thermodynamic activation parameters were calculated and discussed in terms of solvation of the activated complex. No linearity was observed between log rate constant and the reciprocal dielectric constant for the solvent used suggesting that there is a selective solvation by higher polar solvent (water). Finally, a mechanism for the ring opening for isatin and N-methylisatin was proposed.     

Measurement of activity coefficients at infinite dilution in 1-hexadecyl-3-methylimidazolium tetrafluoroborate ionic liquid

This work reports activity coefficients at infinite dilution of 31 organic compounds in 1-hexadecyl-3-methylimidazolium tetrafluoroborate [C₁₆MIM][BF₄] determined using inverse gas chromatography. The measurements were carried out at temperatures (323.15, 333.15, and 343.15) K. Flory–Huggins interaction parameter and solubility parameter were calculated from an experimental retention data.     

Thermophysical and sonochemical behaviour of binary mixtures of decan-1-ol with halohydrocarbons at (T = 293.15 and 313.15) K

Densities and ultrasonic velocities of binary mixtures of decan-1-ol with 1,2-dichloroethane, 1,2-dibromoethane, and 1,1,2,2-tetrachloroethene have been measured over the entire range of composition at T = (293.15 and 313.15) K and at atmospheric pressure. From these results, the excess molar volumes, molar free volumes, excess molar isentropic compressibilities, limiting excess partial molar volumes, and isentropic compressibilities, intermolecular free lengths, and available volumes by three methods, thermal expansion coefficients, parameters related to space-filling ability, intermolecular free lengths, and molecular radii have been calculated. The experimental ultrasonic velocities have been analyzed in terms of the ideal mixture relations of Nomoto and Van Dael, Jacobson’s free length, Schaaff’s collision factor, Flory’s statistical, and Prigogine–Flory–Patterson theories and thermoacoustical parameters.     

Excess thermodynamic properties of binary mixtures of N,N-dimethylacetamide with water or water-d2 at temperatures from 277.13 K to 318.15 K

Densities of binary mixtures of N,N-dimethylacetamide (DMA) with water (H₂O) or water-d₂ (D₂O) were measured at the temperatures from T=277.13 K to T=318.15 K by means of a vibrating-tube densimeter. The excess molar volumes V_m^E, calculated from the density data, are negative for the (H₂O + DMA) and (D₂O + DMA) mixtures over the entire range of composition and temperature. The V_m^E curves exhibit a minimum at x(DMA)≅0.4. At each temperature, this minimum is slightly deeper for the (D₂O + DMA) mixtures than for the corresponding (H₂O + DMA) mixtures. The difference between D₂O and H₂O systems becomes smaller when the temperature increases. The V_m^E results were correlated using a modified Redlich–Kister expansion. The partial molar volume of DMA plotted against x(DMA) goes through a sharp minimum in the water-rich region around x(DMA)≅0.08. This minimum is more pronounced the lower the temperature and is deeper in D₂O than in H₂O at each temperature. Again, the difference becomes smaller as the temperature increases. The excess expansion factor α^E plotted against x(DMA) exhibit a maximum in the water rich region of the mole fraction scale. At each temperature, this maximum is higher for the (D₂O + DMA) mixtures than for the corresponding (H₂O + DMA) mixtures, and the difference becomes smaller as the temperature increases. At its maximum, α^E can be even more than 25 per cent of total value of the cubic expansion coefficient α in the (H₂O + DMA) and (D₂O + DMA) mixtures.