A comparative and systematic thermodynamic study of aqueous solutions and hydrogels of homo- and copolymers of poly(vinyl alcohol)

Nagy, Miklós

doi:10.1039/b001017k

Cited by 13 publications

(23 citation statements)

References 17 publications

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“…The copolymers were synthesized by reacetylating the completely hydrolyzed and fractionated PVA with acetic acid in aqueous solution at 333 K. The so-called blocky type of copolymer was prepared by saponification of poly(vinyl acetate) (PVAc) (Mowilith–50, Hoechst, Germany) dissolved in acetone with NaOH. All other details are given in earlier works. − Some important characteristics of the linear polymer samples are summarized in Table 1 (S1, Supporting Information). The higher softening temperature of the “blocky” copolymer compared with that of the statistical copolymer sample indicates the presence of pure VOH blocks along the polymer chains. , …”

Section: Methodsmentioning

confidence: 99%

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Sorbent Mass Variation Method: A New Possibility for the Determination of Binding Isotherms

et al. 2016

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Measurement of equilibrium mass fraction of a surfactant as a function of the sorbent mass fraction was performed on gel sorbentsolution systems in order to determine binding isotherms and to calculate fundamental characteristics of the solvation layer. With application of this new method it was possible to calculate specific solvation/sorption capacity and absolute average local composition of the solvation layer. It has been pointed out by systematic variation of the composition (hydrophobicity) and degree of cross-linking of the gel sorbents that the ratio of components in the solvation layer can be constant in a given range of equilibrium mass fraction of the sodium dodecylsulfate (SDS) and that the specific solvation/sorption capacity of gel sorbents can be much greater than that of activated carbon type adsorbents.On the basis of a mixed sorbent models it turned out from calculations that there is no preferential binding of SDS close to the chemical cross-links and the surfactant molecules prefer vinyl acetate groups as binding sites. The density of cross-links regulates the aggregation number of the bound surfactant as well. For loose gels both binding isotherms and swelling curves show that the surfactantpolymer interaction is a strongly cooperative process.The result of these experiments may influence general concept of solvation/sorption isotherms and all related phenomena.

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Section: Methodsmentioning

confidence: 99%

“…36,37 Preparation of Gels. 38 The hydrogels were synthesized in the form of 1 mm thick gel membranes in between glass sheets. The concentration of the PVA and copolymers during the cross-linking reaction was 0.205 mol repeat units/100 cm 3 (approximately 10 mass %).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Sorbent Mass Variation Method: A New Possibility for the Determination of Binding Isotherms

et al. 2016

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“…For solvent activity, a 1 , measurements in polymer solutions by the gel deswelling method, composition, degree of cross-linking, and size of the gel laminae had been optimized to achieve the highest sensitivity in a previous work . In the present work, measurements were carried out using chemically cross-linked poly[(vinyl acetate)- co -(vinyl alcohol)] copolymer gels of the composition 8:10:400.…”

Section: Methodsmentioning

confidence: 99%

“…In the present work, thermodynamic measurements were carried out by a relative method, called gel deswelling, − which enables determination of the thermodynamic activity of the solvent exclusively in polymer solutions. This method is based on the phenomenon that the degree of swelling (i.e., the solvent uptake) of a gel highly and explicitly depends on the activity of the solvent if it is placed in a mixture from which the solute cannot enter the network.…”

Section: Introductionmentioning

confidence: 99%

Role of Linear Charge Density and Counterion Quality in Thermodynamic Properties of Strong Acid Type Polyelectrolytes: Divalent Transition Metal Cations

Horváth

Nagy

2006

Langmuir

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Thermodynamic properties of aqueous solutions of poly[(vinyl alcohol)-co-(vinyl sulfate)] (PVAS) copolymer polyelectrolytes with divalent transition metal (Co(II), Ni(II), and Cu(II)) counterions have been determined by the gel deswelling method in the concentration range of 0.0005-0.12 mol of counterion/kg of water (0.09-9 w/w% of the polymer). The influence of the chemical nature of the counterion as well as the effect of the composition of the copolymer from small to medium linear charge density have been systematically studied. Solvent activity, reduced osmotic pressure, the Flory-Huggins pair interaction parameter, rational osmotic coefficients, and degrees of dissociation were calculated from the measured data. No difference could have been observed between the three counterions. Reduced osmotic pressure curves are found to be convex from above, as for Na+ counterions studied previously, which is contrary to the usual behavior of neutral polymers. Intercepts are increasing, and the calculated apparent molar masses and degrees of dissociation at infinite dilution are decreasing with increasing linear charge density of the polyelectrolytes. The pair interaction parameters show a considerable negative deviation from linearity, except for the high volume fraction region. From the differences, concentration dependence of degrees of dissociation could have been calculated. The values at infinite dilution are in good agreement with those obtained from the intercepts of the reduced osmotic pressure curves. Degrees of dissociation seem to decrease approximately linearly with increasing concentration and reach zero at finite concentrations. Rational osmotic coefficients have been calculated in three different ways, both regarding and neglecting the change in the degrees of dissociation.

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“…The reduced osmotic pressure calculated from GDT data were always slightly lower than those obtained from direct osmotic pressure measurement. Likely, this is due to the way of calibration of GDT details of which have been given earlier [23]. Namely, in these works [1,23] the virial coefficients for the PVP K 60 sample were taken from the literature, but the PVP sample used in these studies was not exactly the same as what was applied in that osmotic pressure measurement [9] although its characteristic data were very close to it [22].…”

Section: Results Of Osmotic Pressure Measurements and Some General Immentioning

confidence: 99%

Thermodynamic study of aqueous solutions of polyelectrolytes of low and medium charge density without added salt by direct measurement of osmotic pressure

Nagy

2010

The Journal of Chemical Thermodynamics

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A comparative and systematic thermodynamic study of aqueous solutions and hydrogels of homo- and copolymers of poly(vinyl alcohol)

Cited by 13 publications

References 17 publications

Sorbent Mass Variation Method: A New Possibility for the Determination of Binding Isotherms

Sorbent Mass Variation Method: A New Possibility for the Determination of Binding Isotherms

Role of Linear Charge Density and Counterion Quality in Thermodynamic Properties of Strong Acid Type Polyelectrolytes: Divalent Transition Metal Cations

Thermodynamic study of aqueous solutions of polyelectrolytes of low and medium charge density without added salt by direct measurement of osmotic pressure

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