Liquid-liquid phase equilibria of aqueous two-phase systems containing salts and polyethylene glycol

Liquid-liquid phase equilibria of the ternary systems: (a) polyethylene glycol - ammonium sulfate- water and (b) polyethylene glycol - sodium carbonate -water have been determined experimentally at 15°, 25°, 35° and 45°C and for two different molecular weights of the polymer (Avg. M.W. 1000 and 2000). Details of the glass cell and of the equilibration and analytical procedures used are described. Equilibrium data along with phase diagrams are presented. Finally the effect of temperature and of the molecular weight of the polymer are also discussed.     

Marangoni effects in aqueous polypropylene glycol foams

The foam behavior of three polypropylene glycols covering the molecular weight range between 192 and 725 g/mol has been examined. Static and dynamic surface tension data, as well as bubble size distribution and retention time in the foam, were incorporated into a simple model of foam stability. The latter clearly indicates that surface tension differences between the plateau border and lamellar region adjacent to the bubble surface are the dominant factor in controlling foamability, causing liquid flow in the direction opposite to liquid drainage, a process termed the Marangoni effect.     

微盘电极应用-聚在乙二醇离子导体中的伏安分析

在聚乙二醇离子导体中, 研究了二茂铁在其中的伏安性质, 结果表明如果电活性物质与聚合物溶剂不发生相互反应, 那么电活性物质在聚合物溶剂中的扩散仍然遵循Fick扩散方程, 其伏安结果可以定量描述。提出了在聚合物离子导体中不需要知道电活性物质的摩尔浓度就可估算扩散系数的伏安方法, 探索了在聚合物离子导体中电活性物质的扩散规律。     

Kinetic analysis of glycol mixtures

A kinetic method of analysis is outlined for the determination of two-component mixtures of ethane-diol, propane-1,2-diol and butane-2,3-diol, based on the measurement of reaction rates with lead tetraacetate in acetic acid solution. The method is of limited application only for ethane- and propane-diol mixtures but should prove useful for the analysis of butane-diol/propane-diol and butanediol/ethane-diol systems, the lower limit of concentration ratio being 1:100 and 1:1000 respectively.     

聚乙二醇双水相萃取光度法测定镍

用水溶性高聚物、表面活性剂及有机物与无机盐形成的双水相体系萃取分离色素、蛋白质及测定金属离子已有报道[1-5].     

Influence of salts on hydrophobically end-capped polyethylene oxides in aqueous solution

The influence of four different salts (NaCl, KBr, CaCl₂ and MgCl₂) on the associative behaviour of poly(ethylene oxide) (POE with M=32000g/mol) hydrophobically end-capped with hexadecyl groups in aqueous solutions was investigated. Phase diagrams were obtained, structural properties were established by small angle neutron scattering (SANS) measurements and studies on the viscoelastic properties of the solutions were performed by low-shear viscosity and dynamic stress experiments. The influence of the four salts is compared as well as the difference of the interactions obtained with and without salts.     

Adsorption of polyethylene glycol from aqueous solution on montmorillonite clays

Adsorption rates and capacities of polyethylene glycol (PEG) were investigated for five montmorillonite clays. The adsorption of PEG for all the montmorillonite clays was rapid, and equilibrium was attained within 30 min. The adsorption isotherms of PEG for all the montmorillonites conformed to the Freundlich equation. The adsorption heats were 7.3 and 11.6 kJ · mol^–1(mw.:2000), and 8.7 and 14.2 kJ · mol^–1(mw.:20000) for the montmorillonite and the bentonite II-Ca, respectively. Adsorption capacities for all the clay samples approached constants for the molecular weight of PEG over 2000, though they increased with the increase of molecular weight under 2000. The adsorption capacities were slightly influenced by a nearly neutral pH. The montmorillonite clays which had different interlayer cations showed quite different adsorption capacities. The bentonite II-Ca, the acid clay, and the activated clay showed large adsorption capacities that were 30–50 % of that of an activated carbon.     

Thermodynamics of aqueous solutions of poly ethylene glycol di-methyl ethers in the presence or absence of ammonium phosphate salts

Precise measurements of density and sound velocity at different temperatures ranging from 283.15 to 308.15 K for solutions of PEGDME250, PEGDME500 and PEGDME2000 in water and of PEGDME500 in aqueous solutions of 0.500 mol kg⁻¹ ammonium di-hydrogen phosphate ((NH₄)H₂PO₄) and di-ammonium hydrogen phosphate ((NH₄)₂HPO₄), binodal curves at temperature ranges 293.15-318.15 K for the aqueous PEGDME500 + (NH₄)₂HPO₄, PEGDME500 + (NH₄)₃PO₄, PEGDME2000 + (NH₄)H₂PO₄, PEGDME2000 + (NH₄)₂HPO₄, PEGDME2000 + (NH₄)₃PO₄ and PPG400 + (NH₄)₂HPO₄ two-phase systems, and liquid-liquid equilibrium data at temperature ranges 298.15-318.15 K for the aqueous PEGDME500 + (NH₄)₂HPO₄ and PEGDME2000 + (NH₄)₂HPO₄ two-phase systems have been taken. From the experimental density and sound velocity data, the apparent specific volume, excess specific volume, isentropic compressibility and isentropic compressibility deviation values have been determined and the effect of temperature, charge on the anion of electrolytes and molar mass of PEGDME on the volumetric and compressibility properties of the investigated polymer solutions as well as on the salting-out effect of PEGDMEs produced by ammonium phosphate salts has been studied.     

Identification and quantification of polyethylene glycol types in polyethylene glycol methyl ether and polyethylene glycol vinyl ether

Quantitative determination of polyethylene glycol (PEG) impurities in two monofunctional polyglycol types, PEG methyl ether (M-PEG) and PEG vinyl ether (V-PEG), has been carried out by reversed-phase liquid chromatography with evaporative light scattering detection (ELSD). In addition to optimizing the resolution between PEG and monofunctional PEG peaks, the major focus has been to determine the molecular weights of PEG impurities in M-PEG and V-PEG of diverse molecular weights. The latter is achieved by examining liquid chromatography–mass spectrometry (LC–MS) mass spectra of both monofunctional PEG and PEG in several cases, and matching peak retention times with those of available PEG standards for all M-PEG and V-PEG sample types. This information is helpful in selecting the appropriate PEG standard to determine PEG content in each sample type. ELSD response factors for various PEG standards have also been compared. It has been found that PEG standards with molecular weights from 1000 Da to 8000 Da show responses that are within 10% of each other. However, a low molecular weight PEG such as PEG 400, provides approximately 30% less response compared to its higher molecular weight counterparts.     

Studies of a soluble polyethylene glycol immobilized ruthenium catalyst in aqueous media

We have developed an air-stable soluble polyethylene glycol bound ruthenium catalyst which performs efficient ring-closing metathesis in organic solvents as well as in aqueous media.     

Properties of polyethylene glycol supported tetraarylporphyrin in aqueous solution and its interaction with liposomal membranes

5,10,15,20-Tetrakis(4-hydroxyphenyl)porphyrin was functionalized by covalent attachment of poly(ethylene glycol) (PEG) chains of various molecular weights, 350, 2000, and 5000 Da. The properties of PEG-functionalized tetraarylporphyrins in aqueous solution and their interactions with liposomes have been studied. Electronic absorption spectroscopy, dynamic light scattering, atomic force microscopy, and fluorescence quenching were used to monitor aggregation of porphyrin chromophores and behavior of the attached PEG chains in the aqueous solution. The tendency for aggregation of porphyrin chromophores in aqueous solution and the efficiency of fluorescence quenching by KI decrease with increasing length of PEG chain linked to the porphyrin ring. The experimental results indicate that polymer clusters are present in aqueous solution of all pegylated porphyrins. The interactions between the pegylated porphyrins and phosphatidylcholine liposomes in the aqueous solution were studied using the fluorescence methods. The apparent binding constants of porphyrin chromophores to liposomes were determined. The degree of binding was found to be dependent on the molecular weight of the attached polymer.     

聚醚型非离子表面活性剂的混合表面膜III, 环氧乙烷一环氧丙烷嵌段共聚物, 聚丙二醇与十六醇, 硬脂酸的二元混合物

本文进一步研究了环氧乙烷-环氧丙烷嵌段共聚物(L61和F68)、聚丙二醇(PPG)分别与十六醇(CA)、硬脂酸(SA)所形成的二元混合膜。根据对π-α实验结果的分析, 表明PPG-CA、PPG-SA、F68-SA和L61-SA的混合单分子膜是不相混溶的, 而L61-CA和F68-CA的混合单分子膜则是混溶的。     

Relative permittivity of the binary mixtures of 2-methoxyethanol with diethylene glycol,triethylene glycol,tetraethylene glycol,and polyethylene glycol 200 at various temperatures

Relative permittivities at T = (293.15, 298.15, and 303.15) K in the binary liquid mixtures of 2-methoxyethanol with diethylene glycol, triethylene glycol, tetraethylene glycol, and polyethylene glycol 200 have been measured over the entire mixture compositions. The relative permittivity deviations (Δε) were calculated from these experimental data. The results are discussed in terms of intermolecular interactions and structure of studied binary mixtures.     

聚乙二醇双水相萃取光度法测定锌

A novel method of extraction spectrophotometric determination of Zn~(2+) in aqueous two-phase system formed by polyethylene glycol-2000,sodium sulfate and zincon has been established.Amounts of PEG solution,zincon solution,sodium sulfate added and the acidity of the system were optimized.The interference effects of various coexistent ions and the method to remove the interference were investigated.The Zn-zincon complex that had been formed in the presence of H_2BO_3-Na_2B_4O_7 buffer solution at pH 7.4 was extracted into the upper PEG-rich phase,and the absorbance of the extracted complex in the upper PEG-rich phase was measured at 630 nm.The apparent molar absorptivity was 7.3 × 10~4 L / (mol·cm).Beer's law was obeyed over the range of 0～2.0 μg / mL Zn~(2+).The analytical results obtained for Zn~(2+) in water samples were in good agreement with values measured by atomic absorption spectrometry.     

Conformational characteristics of polyethylene glycol macromolecules in aqueous solutions according to refractometry data

The aqueous solutions of polyethylene glycols with molecular masses of 600, 1000, 1500, 3000, 6000, and 20000 were studied by refractometry. The conformational polarizabilities, mean-square distances between the ends of the macromolecular chain, segment lengths, and the number of Kuhn segments in a macromolecule were determined using the Lorentz-Lorentz equation. The polarizability of a hydrated macro-molecule was represented as the sum of polarizabilities of the nonhydrated macromolecule with retained conformation and polarizabilities of the water molecules involved in hydration of macromolecules. The size of macromolecules stabilized starting from a certain concentration. It was concluded that the initial concentration of stabilization shifts toward low concentrations as the molecular mass of polyethylene glycol increases. The dependence of the mean-square distance between the ends of the macromolecular chain on the number of Kuhn segments was expressed as the exponential function with index 0.3.     

两相体系分光光度法测定聚乙二醇化蛋白质混合物中游离聚乙二醇

建立了用硫氰酸铁胺-氯仿两相体系分光光度法测定游离聚乙二醇含量的方法。确定了最大吸收波长，考察了混合振荡时间、其他生物大分子存在对测定结果的影响，并与三硝基苯磺酸(TNBS法)进行了比较。     

The association of aqueous phenolic resin with polyethylene oxide and poly(acrylamide-co-ethylene glycol)

Comb copolymers formed from acrylamide and poly(ethylene-glycol) methacrylate macro-monomer (PAM-co-PEG) were compared to poly(ethylene oxide) (PEO) with respect to hydrogen bond complex formation with water-borne phenolic resins. The behaviors of the two types of high molecular weight polyethers were similar. Complex formation gave a transient increase in viscosity followed by precipitation. Copolymers with pendant PEG chain lengths ≥ 9 formed complexes with phenolic resin whereas PEG homopolymer with a molecular weight of 2000 did not form a complex. For both copolymer and high molecular weight PEO, the tendency of the complex to precipitate increased when the pH was decreased from 7 to 4. Acridine orange, a cationic dye, bound to the phenolic resin and, after the addition of PEO, yielded visible complex gels with diameters about 20 μm. © 1995 John Wiley & Sons, Inc.     

Excess molar volumes of the binary mixtures of polyethylene glycol 300 with ethoxyethanols at various temperatures

Densities at T = (293.15, 298.15, 303.15, 308.15, and 313.15) K in the binary liquid mixtures of polyethylene glycol 300 with 2-ethoxyethanol, 2-(2-ethoxyethoxy)ethanol, or 2-{2-(2-ethoxyethoxy)ethoxy}ethanol have been measured over the entire range of mixture compositions. These data have been used to compute the excess molar volumes. The excess molar volumes are negative over the entire range of composition for all studied mixtures. The results are discussed in terms of intermolecular interactions in the bulk binary mixtures.     

Investigation on properties of aqueous foams stabilized by aliphatic alcohols and polypropylene glycol

Foams stabilized by nonionic surfactants are usually moderately stable due to high drainage rate and intense bubble coalescence and coarsening. This study aimed to investigate comparatively the foam properties of aliphatic alcohols (methyl isobutyl carbinol (MIBC) and 2-octanol) and polypropylene glycol (PPG400). Experiments were conducted using the FoamScan method at various surfactant concentrations and gas flow rates where the foam volume, liquid content of foam and foam half-life were determined. The results showed that both foamability and foam stability of surfactant solution increased with increasing gas flow rate and surfactant concentration for all tested surfactants. PPG400 was an unusually strong surfactant having the largest surface activity compared with MIBC and 2-octanol, which exhibited the maximum foaming performance and foam stability at all tested gas flow rates and concentrations. The present study suggested that foam properties depended primarily on the type of surfactant and its concentration and secondarily on the gas flow rate. In addition, properties of interface are closely related to that of foam, which is a significant point if one wants to produce foams for specific applications.