Ionic Diffusion in Polymers

Boeykens, Susana; Daraio, Marta E.; Temprano, N.; Rosen, M.

doi:10.1002/masy.200550930

Cited by 5 publications

(5 citation statements)

References 2 publications

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“…Diffusion in aqueous polymer solutions has previously been studied by monitoring electric conductivity as a function of polymer concentration and molar mass. − In electric conductivity measurements, cations and anions within an electric field move through solution toward an appropriately charged electrode, where ions are either oxidized or reduced, resulting in current. How rapidly ions arrive at the electrode is dependent upon ion mobility through the medium, allowing for an assessment of molecular level rheological properties.…”

Section: Resultsmentioning

confidence: 99%

Macro- and Microscale Rheological Properties of Poly(vinyl alcohol) Aqueous Solutions

et al. 2011

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Electric conductivity measurements indicated that microviscosities of poly(vinyl alcohol), PVA, solutions [up to 10% (w/w)] are comparable to that of pure water (contrary to Walden's rule), but are different (25%) from those determined from diffusion-controlled reaction measurements that coincide with the values obtained using pure water. Energies of activation of fluidity of PVA solutions are found to increase with PVA concentration, whereas those of the diffusion-controlled reactions are independent of PVA concentration. By comparing the macro- and microviscosities, it was concluded that PVA aqueous solutions can be envisioned as dynamic systems comprising hydrated PVA molecules (that affect the macroviscosity) and "interconnected water pools" (located between macromolecules), the rheological properties of which are very similar to that of pure water. Fluorescence depolarization measurements indicated that pool sizes are relatively large, which was corroborated by DSC measurements that showed that each PVA hydroxyl group interacts with no more than two water molecules.

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Section: Resultsmentioning

confidence: 99%

Macro- and Microscale Rheological Properties of Poly(vinyl alcohol) Aqueous Solutions

et al. 2011

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“…In addition, we used the well-established diffusion-controlled electron transfer reaction of excited state *Ru(bpy) 3 2+ with methyl viologen, MV 2+ , − a somewhat larger ( r = ∼0.5 nm) divalent cationic quencher, to assess ion mobility through the protein hydrogel of the thick fraction. Ion diffusion in aqueous polymer solutions has also been investigated by monitoring electric conductivity as a function of polymer concentration and molar mass − and is used here to further examine ion mobility within the thick fraction.…”

Section: Resultsmentioning

confidence: 99%

Mobility of Molecules and Ions Solubilized in Protein Gels: Diffusion in the Thick Fraction of Hen Egg White

Krise

Milosavljevic

2011

Biomacromolecules

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The thick fraction of hen egg white is a protein hydrogel with an immeasurably high viscosity composed of ∼90% water that can serve as a model system for mammalian mucous membrane. Measurements of the rate constants of diffusion-controlled reactions occurring within the gel (and corresponding activation energies) and electric conductivity revealed that the thick fraction of egg white can be envisioned as a 3D network comprising hydrated protein molecules (held by intermolecular S-S bridges) surrounded by water pools and channels (of nonuniform diameters) that have a microviscosity that is very similar to that of bulk water. This was corroborated by differential scanning calorimetry measurements that revealed that 16% of water is bound to proteins. The melting kinetics of ice crystallites (produced from the freezable water) indicates nonhomogeneous water pool size.

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“…Substituted benzenesulphonic acid esters of cellulose are investigated in terms of the S N reaction with lithium acetate, and a reaction mechanism is proposed [277]. Introduction of heavy atoms for X-ray fluorescence spectroscopy [281,282] The fluorine-containing aliphatic sulphonic acid esters of polysaccharides exhibit a high reactivity and have to be handled carefully. The conversion of trifluoromethanesulphonic acid anhydride with methyl cellulose and cellulose acetate was used for the preparation of cross-linked gels [269].…”

Section: Miscellaneous Sulphonic Acid Estersmentioning

confidence: 99%