Mazur, Kamila and Buchner, Richard and Bonn, Mischa and Hunger, Johannes (2014) Hydration of Sodium Alginate in Aqueous Solution. MACROMOLECULES, 47 (2). pp. 771-776. ISSN 0024-9297, 1520-5835
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Alginates are naturally occurring biocompatible polysaccharides. They have a broad range of applications, mainly in connection to their ability to control the rheology of aqueous solutions. Specifically, addition of a small amount of alginate (10% wt) leads to a similar to 100-fold increase in viscosity. Here we explore whether that pronounced retardation of the long-range correlations is accompanied by molecular-level changes of the water structure. We employ viscometry, dielectric spectroscopy (DS) and femtosecond infrared (fs-IR) pump probe spectroscopy to study water dynamics in sodium alginate solutions. Remarkably, despite the large rheological effects of alginates in solution, the rotational dynamics of water are remarkably similar to those observed in bulk water. Only a small subensemble of water molecules is slowed down significantly, amounting to 6 +/- 2 water molecules per saccharide unit. Furthermore, DS measurements reveal an additional similar to 5 water molecules to be slowed down by the counterion (Na+). Our results reveal that the effect of alginate on the dynamics of water is restricted to the first hydration shell. This indicates that the large viscosity increase is determined by the polysaccharide network, with large water pools present between the polysaccharide chains.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | DIELECTRIC-RELAXATION; WATER REORIENTATION; DYNAMICS; IONS; SPECTROSCOPY; MOLECULES; HDO; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie Chemistry and Pharmacy > Institut für Physikalische und Theoretische Chemie > Chair of Chemistry VI - Physical Chemistry (Solution Chemistry) > PD Dr. Richard Buchner |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 28 Nov 2019 10:02 |
| Last Modified: | 28 Nov 2019 10:02 |
| URI: | https://pred.uni-regensburg.de/id/eprint/10792 |
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