The equivalent conductivity of aqueous solutions of alkali metal salts of a number of ionic polysaccharides

Kwak, Jan C. T.; Murphy, Gëorge F.; Spiro, Ester J.

doi:10.1016/0301-4622(78)85014-5

Cited by 29 publications

(17 citation statements)

References 22 publications

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“…The disagreement between experimental and predicted Λ values was also noticed for other polyelectrolytes and attributed to some effects which are not assumed by Manning in his theory, like polyion-polyion interactions, a different dielectric constant in the immediate neighborhood of the polyion than that in the pure bulk solvent, the lower values of the experimental interaction parameter than the calculated ones, etc. [11,22,45,46]. We have checked the last assumption and the results are presented in the following paragraph.…”

Section: Conductivity Measurementsmentioning

confidence: 93%

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Transport properties of some cationic polysaccharides

Ghimici¹,

Nichifor²

2006

Journal of Colloid and Interface Science

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Section: Conductivity Measurementsmentioning

confidence: 93%

“…The values of Λ theo were calculated from Eqs. (4)-(7), assuming r = 0.7 nm [45]; the λ 0 c values were taken from the literature [37]. The experimental values are, clearly, lower than the theoretical ones for all cationic polysaccharides in water and for D40-Et94 in water/methanol mixtures.…”

Section: Conductivity Measurementsmentioning

confidence: 99%

Transport properties of some cationic polysaccharides

Ghimici¹,

Nichifor²

2006

Journal of Colloid and Interface Science

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“…According to the literature, 15,37,38 the concentration range of 0.1-2.4 mg ml À1 of chitosan solution in this work belongs to the semidilute region. In this concentration range, only intramolecular interactions and polyion-solvent interactions occur, without polyion-polyion interactions.…”

Section: Modelling Description Of Counterions In a Semidilute Chitosa...mentioning

confidence: 99%

Dielectric relaxations in chitosan solution with varying concentration and temperature: analysis coupled with a scaling approach and thermodynamical functions

Liu

Zhao

2010

Soft Matter

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The dielectric properties of chitosan in an aqueous solution with no added salts have been measured as a function of concentration and temperature in the frequency range from 40 Hz to 110 MHz, respectively. After reducing the contribution of the electrode polarization effects, the dielectric spectra of chitosan semidilute solutions show two relaxations at 100 kHz and MHz, respectively. The observed two dielectric relaxations have been strictly analyzed using the Cole-Cole function and the possible relaxation mechanisms were attributed to the fluctuation of condensed counterions and free counterions, respectively. The dependence of the dielectric increment and relaxation time on concentration was interpreted in light of the scaling properties of polyelectrolyte solutions. It was found that the dependence of relaxation time on the C p follows the expected exponents of the scaling laws, both in the low-frequency and high-frequency cases. The good agreement between experimental results and theoretical analysis suggests that the low-and high-frequency relaxation mechanisms are the fluctuation of condensed counterions and free counterions, respectively. In addition to this, this analysis gives further support to the scaling approach of the dynamic behavior of polyelectrolytes. The temperature dependence of the dielectric spectrum of chitosan solutions showed that the low-and highfrequency dielectric increment generally decreases with the rise of temperature, which is considered to be due to the acceleration of the reorientation motion of the counterions. Moreover, the thermodynamic parameters, such as activation free energy E a , activation enthalpy change DH and activation entropy change DS of low-and high-frequency were calculated from the relaxation time, and discussed from the microscopic thermodynamical view.

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“…In addition, most of experimental work has been carried out at concentrations too high to be considered highly diluted, 29,30,36,37,42,45,47,48 hence preventing rigorous model discrimination. Furthermore, the water quality often did not correspond to that required for salt-free conditions.…”

Section: Introductionmentioning

confidence: 99%

Counterion Activity of Highly Charged Strong Polyelectrolytes

et al. 2000

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Comprehensive counterion activity studies have revealed clear influence of the polyelectrolyte concentration and chain length on the polyion-counterion interaction, neither of which is evident from the existing theoretical models. The counterion activity coefficient (f a) increases below the overlap concentration c* as calculated from Odijk's scaling approach. At dilutions where the Debye length (lD) exceeds the contour length (L), this increase is more pronounced. It is concluded that these changes in the ionic interactions are primarily responsible for the strong increase of the equivalent conductivity (Λ) below c*. The findings are not restricted to oligomers but apply to all chain lengths of polyelectrolytes at concentrations less than c*. The correlation of fa and Λ with both c* and the ratio lD/L leads to a general description of polyelectrolyte behavior. Experiments were performed above and below c* and over the range 0.1 e lD/L e 10 using a series of poly(vinylbenzyltrialkylammonium) model polyelectrolytes with contour lengths over a range 7 nm e L e 102 nm and characterized by a charge density parameter ) 2.85.

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The equivalent conductivity of aqueous solutions of alkali metal salts of a number of ionic polysaccharides

Cited by 29 publications

References 22 publications

Transport properties of some cationic polysaccharides

Transport properties of some cationic polysaccharides

Dielectric relaxations in chitosan solution with varying concentration and temperature: analysis coupled with a scaling approach and thermodynamical functions

Counterion Activity of Highly Charged Strong Polyelectrolytes

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