at Google ScholarTitle data
Dudko, Volodymr ; Rosenfeldt, Sabine ; Siegel, Renée ; Senker, Jürgen ; Matejdes, Marian ; Breu, Josef:
Delamination by Repulsive Osmotic Swelling of Synthetic Na-Hectorite with Variable Charge in Binary Dimethyl Sulfoxide–Water Mixtures.
In: Langmuir.
Vol. 38
(2022)
Issue 35
.
- pp. 10781-10790.
ISSN 1520-5827
DOI: https://doi.org/10.1021/acs.langmuir.2c00965
Abstract in another language
Swelling of clays is hampered by increasing layer charge. With vermiculite-type layer charge densities, crystalline swelling is limited to the two-layer hydrate, while osmotic swelling requires ion exchange with bulky and hydrophilic organic molecules or with Li+ cations to trigger repulsive osmotic swelling. Here, we report on surprising and counterintuitive osmotic swelling behavior of a vermiculite-type synthetic clay [Na-0.7](inter)[Mg2.3Li0.7](oct)[Si-4](O10F2)-O-tet in mixtures of water and dimethyl sulfoxide (DMSO). Although swelling in pure water is restricted to crystalline swelling, with the addition of DMSO, osmotic swelling sets in at some threshold composition. Finally, when the DMSO concentration is increased further to 75 vol %, swelling is restricted again to crystalline swelling as expected. Repulsive osmotic swelling thus is observed in a narrow composition range of the binary water-DMSO mixture, where a freezing point suppression is observed. This suppression is related to DMSO and water molecules exhibiting strong interactions leading to stable molecular clusters. Based on this phenomenological observation, we hypothesize that the unexpected swelling behavior might be related to the formation of different complexes of interlayer cations being formed at different compositions. Powder X-ray diffraction and Na-23 magic angle spinning-NMR evidence is presented that supports this hypothesis. We propose that the synergistic solvation of the interlayer sodium at favorable compositions exerts a steric pressure by the complexes formed in the interlayer. Concomitantly, the basal spacing is increased to a level, where entropic contributions of interlayer species lead to a spontaneous thermodynamically allowed one-dimensional dissolution of the clay stack.
Further data
| Item Type: | Article in a journal |
|---|---|
| Refereed: | Yes |
| Additional notes: | WOS:000885892800001 |
| Institutions of the University: | Faculties Faculties > Faculty of Biology, Chemistry and Earth Sciences Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Inorganic Chemistry III > Chair Inorganic Chemistry III - Univ.-Prof. Dr. Jürgen Senker Research Institutions > Central research institutes > Nordbayerisches Zentrum für NMR-Spektroskopie - NMR-Zentrum Faculties > Faculty of Biology, Chemistry and Earth Sciences > Department of Chemistry > Chair Inorganic Chemistry III Research Institutions Research Institutions > Central research institutes |
| Result of work at the UBT: | Yes |
| DDC Subjects: | 500 Science 500 Science > 540 Chemistry |
| Date Deposited: | 19 Dec 2022 12:08 |
| Last Modified: | 05 Jun 2023 09:20 |
| URI: | https://eref.uni-bayreuth.de/id/eprint/73057 |