Salt effects on the cloud point of the poly(ethylene oxide)+ water system

Florin, Ebba; Kjellander, Roland; Eriksson, Jan Christer

doi:10.1039/f19848002889

Cited by 227 publications

(258 citation statements)

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“…16 depends upon the valency and hydration of the ions as well as specific interactions of the ions with the ether oxygens of PEG. It is thus expected from the Gibbs free energy of hydration (∆Ghyd) that Na + has a salting-out effect stronger than that of K + , although Florin et al 16 have shown that the difference in the salting-out ability is very small between the two ions. The ∆Ghyd values for Na + and K + are -375 and -304 kJ/mol, respectively.…”

Section: Resultsmentioning

confidence: 99%

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Effects of Phase-Forming Cations and Anions on the Partition of Ionic Solutes in Aqueous Polyethylene Glycol-Inorganic Salt Two-Phase Systems

et al. 2000

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When a certain water-soluble polymer is dissolved in water together with another kind of hydrophilic polymer or with a certain inorganic salt at specific concentrations, two aqueous phases can be formed. These aqueous two-phase systems or aqueous biphasic systems have been successfully used for the separation of biological materials, such as cells, organelles, enzymes and proteins, because they essentially have a nondenaturing environment. 1,2It has also been shown that the aqueous two-phase partition technique can be efficient for the separation of inorganic compounds 2-5 and small organic molecules. 6 Although a number of different water-soluble polymers may be utilized to form aqueous two-phase systems, polyethylene glycols (PEGs) are mainly used in combination with dextrans or inorganic salts. Because PEGs are nontoxic, nonflammable and nonvolatile the PEG-based aqueous two-phase systems cause less environmental problems compared to conventional solventextraction systems utilizing water-immiscible organic solvents.The partition of solute compounds in aqueous two-phase systems depends on numerous factors originating from the polymers and inorganic salts to be used for forming the two phases. As well as the variables concerning the polymers, the type and concentration of the salts are among the most important factors. It has been demonstrated that the ionic composition in aqueous two-phase systems exerts pronounced effects on the partition of solute compounds, particularly on that of ionic solutes. 4,5,7,8 Johansson 7 has indicated that the partition coefficients of ionic solutes in a PEG-dextran two-phase system depends both on the type of salt added to the system as well as the net charge of the solute. Rogers et al. 5 investigated the partition behavior of pertechnetate ion in PEG-alkali metal and ammonium sulfate salt systems, and revealed that the trends in the partition coefficients follow from the relative salting-out ability of the salts used.However, the effects of the salts added upon the partition of solute compounds are rather complex because the concentrations of the polymers in the coexisting phases depend on the type and concentration of the salts. Zaslavsky et al. 9,10 and Bamberger et al. 11 have shown that the salt additives alter the polymer composition of the coexisting phases in the aqueous two-phase systems formed by two different polymers, such as PEG-dextran and Ficoll-dextran. This means that the ionic composition in the aqueous two-phase systems influences the partition of solutes not only by its own effect, but also by the effect on the polymer composition of the two phases. Therefore, the inherent effect of ions on the solute partitioning in aqueous two-phase systems should be evaluated under the conditions where the effect of the polymer concentrations can be regarded as being constant.In the present study, we chose PEG-salt (Na2SO4, K2HPO4 and Na2HPO4) two-phase systems and investigated the partition bahavior of inorganic cations and anions as a function of the difference in the c...

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Section: Resultsmentioning

confidence: 99%

“…Several investigators have studied the influence of the type of inorganic salts on the phase separation of aqueous PEG solutions, [13][14][15][16][17][18] and have suggested that the stronger is the hydration of the ion, the lower is the concentration required to form a two-phase system.…”

Section: Resultsmentioning

confidence: 99%

Effects of Phase-Forming Cations and Anions on the Partition of Ionic Solutes in Aqueous Polyethylene Glycol-Inorganic Salt Two-Phase Systems

et al. 2000

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“…5) [8]. According to Florin's analysis [25], this phenomenon would be related to the influence of salt on the water structure around the PEO macromolecules. For most of the salt studied (Fig.…”

Section: Concept and Designmentioning

confidence: 99%

Reversible Thermoassociation of Water-Soluble Polymers

L'Alloret¹,

Maroy²,

Hourdet³

et al. 1997

Rev. Inst. Fr. Pét.

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TH ERMO ASSOCIATION RÉVERSIBLE DE POLYMÈRES HYDROSOLUBLESThe thermoassociative phenomenon was also studied by Small Angie Neutrons Scattering (SANS, using copolymers composed by a deuterated polyacrylate backbone and protonated polyethyl ene oxide grafts. The scattering properties of our system were studied by varying the temperature, the salinity and the polymer concentration of the solution. A good agreement between the microscopic characteristics of the solutions and their rheological properties was found. TERMOCOMBINACIÓN REVERSIBLE DE POLIMEROS HIDROSOLUBLESLos polimeros hidrosolubles se utilizan corrientemente corno agentes de espesamiento para controlar la reologìa de los fluidos acuosos, en distintos sectores de la industria. No obstante, sus propiedades se debilitan a medida que aumenta la temperatura. Para hacer trente a este problema se ha desarrollado el concepto de polfmeros "termocombinativos" solubles en el agua. Nuevos sistemas anfifilos de este gènero se pueden obtener por injerto en una estructura hidrófila de las cadenas laterales que dejan de ser solubles por encima de una temperatura critica infe rior de solución (Lower Critical Solution Temperature = LCST). Las soluciones semidiluidas de estos copolimeros presentan pro piedades de espesamiento reversibles a medida que aumenta la temperatura y alcanza un valor critico cercano de la temperatura de LCST de las cadenas laterales. Este comportamiento se puede poner en relación con la agregación de elementos de injertos por encima de su temperatura LCST en microsectores hidrófobos que conducen a la formación de una reticulación tridimensional. Con temperaturas màs elevadas, la viscosidad de la solución cizallada con valor constante alcanza un valor maximo. Esto se puede inter pretar en términos de reorganización de la red fisica debido al esfuerzo de cizallamiento, que pasa de una estructura con "combinaciones intermoleculares" principalmente a un sistema con un numero incrementai de "combinaciones intramoleculares". Habida cuenta de la diversidad de los polfmeros solubles en el agua que presentan una separación de fases al proceder a un recalentamiento (LCST), se han realizados distintos copolfmeros "termocombinados" [1] and [2], utilizando un polielectrolito, o sea una estructura hidrófila neutra. Con objeto de proceder a la aplicación de estos sistemas en la industria del petróleo, se han desa rrollado copolfmeros que contienen àcidos sulfónicos de propano 2-acrilamida 2-metil (AMPS) utilizando el óxido de polietilene (PEO) corno elemento de injerto LCST. En el presente artfculo figura una descripción generai de su comportamiento reológico. Sus propiedades se pueden controlar, ya sea variando las caracterfsticas de la solución (concentración de polimero, salinidad, etc.) o por modificación de la estructura quimica del copolimero (relación de injertos, masa molecular, etc.). Este estudio reológico ha demostrado la potencialidad de los sistemas "termocombinativos", particularmente para la industria del petróleo [3]. En la actualidad existe la po...

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“…This is surprising since it is known that anions are less hydrated than cations [21]. The salt effect is thus not due to a water competition effect but must be related to how the ions interact with the solute water interface [18,22,23]. This reasoning is based on surface tension measurements [24,25] which show that anions are repelled from a dielectric discontinuity like the water/air or the water/oil interface in the order F-> Cl-> Br-> I-.…”

Section: Effect Of Sodium Chloridementioning

confidence: 99%

Aqueous micellar systems in membrane protein crystallization

Weckström¹

1985

FEBS Letters

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The effects of NaCl and polyethylene glycol (PEG) 4000 on the lower consolution boundary (LCB) of a nonionic surfactant (C,E,) were studied and compared. Micellar systems where NaCl and PEG 4000 are present are often used in membrane protein crystallization. While sodium chloride shifts the surfactant LCB to lower temperatures without a significant change in the shape of the boundary, PEG produces a large solubility change strongly depending on the surfactant concentration.The salt effect is explained by a reduced interaction of the micellar oligooxyethyiene chains with the water and the PEG effect by an unfavourable configurational interaction between the C,E, micelles and PEG molecules. Detergent Crystallization Membrane protein Polyethylene glycol

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Salt effects on the cloud point of the poly(ethylene oxide)+ water system

Cited by 227 publications

References 1 publication

Effects of Phase-Forming Cations and Anions on the Partition of Ionic Solutes in Aqueous Polyethylene Glycol-Inorganic Salt Two-Phase Systems

Effects of Phase-Forming Cations and Anions on the Partition of Ionic Solutes in Aqueous Polyethylene Glycol-Inorganic Salt Two-Phase Systems

Reversible Thermoassociation of Water-Soluble Polymers

Aqueous micellar systems in membrane protein crystallization

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