Determination of membrane hydration numbers of alkali metal ions by insertion in a conducting polymer

Skaarup, Steen; Jafeen, M. J. M.; Careem, M.A.

doi:10.1016/j.ssi.2010.06.053

Cited by 22 publications

(24 citation statements)

References 16 publications

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“…The membrane hydration numbers obtained for alkali, alkali earth and two rare earth metal cations by this novel method in this work and in our earlier work are summarised in Table 1 together with selected primary hydration number values obtained by other methods [8].…”

Section: Resultsmentioning

confidence: 93%

“…The cycling experiments with simultaneous CV and EQCM measurements were done in aqueous MgCl 2 , CaCl 2 , BaCl 2 , SrCl 2 , YCl 3 and LaCl 3 electrolytes having various concentrations ranging from 0.02 to 1 M. For each experiment, a freshly prepared PPy(DBS) film of 400 nm thickness polymerized under the same experimental conditions was used. For all cycling, a constant scan rate of 2 mV/s was used as optimized in [8]. At this rate, or lower, the ions have time to penetrate the full thickness of the film.…”

Section: Methodsmentioning

confidence: 99%

“…Recently, our group has successfully demonstrated and reported that the primary hydration numbers of alkali metal cations can directly and accurately be determined using the unique physico-chemical environment of polypyrrole (PPy) doped with the large, immobile dodecylbenzene sulfonate (DBS) anions operating in aqueous electrolytes [8]. The first electrochemical cathodic reduction of a freshly prepared PPy(DBS) film, which is in an oxidative form, operating in aqueous phase containing hydrated cations, has been used.…”

Section: Introductionmentioning

confidence: 99%

“…The first electrochemical cathodic reduction of a freshly prepared PPy(DBS) film, which is in an oxidative form, operating in aqueous phase containing hydrated cations, has been used. The present work aims to further extend the studies for determining reliable values for membrane hydration numbers of alkali earth and alkali rare earth metal cations using the same method adopted in [8] and to explore any possible common trends among the membrane hydration number values obtained for the cations. The membrane hydration numbers of alkali earth and alkali rare earth metal cations in respective chloride aqueous electrolytes having various concentrations ranging from 0.02 to 1 M determined using PPy(DBS) conducting polymer are reported in this paper.…”

Section: Introductionmentioning

confidence: 99%

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A novel method for the determination of membrane hydration numbers of cations in conducting polymers

Jafeen

Careem

Skaarup

2011

J Solid State Electrochem

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Polypyrrole polymer films doped with the large, immobile dodecylbenzene sulfonate anions operating in alkali halide aqueous electrolytes has been used as a novel physico-chemical environment to develop a more direct way of obtaining reliable values for the hydration numbers of cations. Simultaneous cyclic voltammetry and electrochemical quartz crystal microbalance technique was used to determine the amount of charge inserted and the total mass change during the reduction process in a polypyrrole film. From these values, the number of water molecules accompanying each cation was evaluated. The number of water molecules entering the polymer during the initial part of the first reduction was found to be constant and independent of the concentration of the electrolyte below ∼1 M. This well-defined value can be considered as the primary membrane hydration number of the cation involved in the reduction process. The goal was to investigate both the effects of cation size and of cation charge. The membrane hydration number values obtained by this simple and direct method for a number of cations are:Li þ : 5:5 À 5:3; Na þ : 4:5 À 4:3; K þ : 2:3 À 2:5;Rb þ : 0:9 À 0:8; Cs þ : $ 0; Mg 2þ : 10:4 À 10:6; Ca 2þ : 7:9 À 8:1; Sr 2þ : 5:7 À 6:1; Ba 2þ : 3:0 À 3:1; Y 3þ : 13:6 À 13:8; La 3þ : 9:0 À 9:1:The hydration number for all of these cations seems to follow the same simple relation.

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Section: Resultsmentioning

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A novel method for the determination of membrane hydration numbers of cations in conducting polymers

Jafeen

Careem

Skaarup

2011

J Solid State Electrochem

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“…Recently, the unique properties of conducting polymers have been used to directly measure the hydration numbers of alkali metal cations in water [14,15].…”

Section: Introductionmentioning

confidence: 99%

Speed and strain of polypyrrole actuators: dependence on cation hydration number

Jafeen

Careem

Skaarup

2009

Ionics

Self Cite

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Polypyrrole films have been characterized by simultaneous cyclic voltammetry driven force-displacement measurements. The aim was to clarify the role of cations in the electrolyte on the speed of response and on the strain of the film. The strain as a function of actuation frequency was studied in alkali metal chloride aqueous electrolytes. The intention was to test the hypothesis of the division of the inserted H 2 O molecules into categories: a smaller number strongly bound to the cation (corresponding to the inner solvation shell) and a larger number entering the film after the insertion of the cations because of forces related to osmotic pressure difference. The two processes have very different time constants: The solvated H 2 O molecules are associated directly with the cations, and are therefore inserted in a faster process, whereas the second type enters the film much more slowly. At higher frequencies, the strain depends almost exclusively on insertion of strongly solvated cations and therefore depends on the hydration number of the cations: Li + (hydration number~5.4) gives more strain than Na + (~4.4) and much more than Cs + (~0) as predicted by the model.

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A Potentiostatic/Galvanostatic Study and Theoretical Description of Polypyrrole Film Electrodes: A Model of the Intracellular Matrix of Ectothermic Muscle Cells

Beaumont

Otero

2017

ChemElectroChem

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Polypyrrole film electrodes are composed of macromolecular electrochemical machines, ions and water. They are considered here as a model of the intracellular matrix of ectothermic muscle cells. The oxidation/reduction responses to the working temperature in aqueous solutions were investigated herein by potential and current steps. Under potentiostatic conditions, rising temperatures stimulate deeper conformational movements of the polymeric chains leading to the exchange of more ions increasing the consumed charge, with the effect that the reaction charge responds and senses the working temperature. Under galvanostatic conditions and higher environmental thermal energies the material potential evolves at lower values during reactions consuming lower electrical energies. At any reaction time, both the consumed reaction energy and the material potential sense the working thermal conditions. Reactions involving molecular machines sense and respond to the working temperature. Similarities with energetic consumptions and sensing responses from muscles in cold‐blooded animals are discussed. A theoretical description is proposed.

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Determination of membrane hydration numbers of alkali metal ions by insertion in a conducting polymer

Cited by 22 publications

References 16 publications

A novel method for the determination of membrane hydration numbers of cations in conducting polymers

A novel method for the determination of membrane hydration numbers of cations in conducting polymers

Speed and strain of polypyrrole actuators: dependence on cation hydration number

A Potentiostatic/Galvanostatic Study and Theoretical Description of Polypyrrole Film Electrodes: A Model of the Intracellular Matrix of Ectothermic Muscle Cells

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