Influence of Pressure on Boron Cross-Linked Polymer Gels
| Autor: | Michael D. Parris, Jerome W. Rathke, Bruce A. MacKay, Rex E. Gerald, Robert J. Klingler |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
chemistry.chemical_classification
Aqueous solution Polymers and Plastics Rheometry Organic Chemistry chemistry.chemical_element Polymer Nuclear magnetic resonance spectroscopy Polyvinyl alcohol Inorganic Chemistry chemistry.chemical_compound Viscosity chemistry Polymer chemistry Materials Chemistry Boron Bar (unit) |
| Zdroj: | Macromolecules. 41:8181-8186 |
| ISSN: | 1520-5835 0024-9297 |
| DOI: | 10.1021/ma801187q |
| Popis: | Using steady-shear rheometry in combination with high-pressure 11B nuclear magnetic resonance spectroscopy (11B NMR), we have found that gels formed from water-soluble polymers containing vicinal hydroxyl groups cross-linked with various boron-containing compounds undergo significant structural changes that result in a pronounced loss of viscosity when placed under pressure. Importantly, gels from other cross-linking agents tested, including Ti(IV) and Zr(IV), did not show this loss in viscosity. The experimental study probed pressure-induced changes to both galactomannan and polyvinyl alcohol (PVA) gels cross-linked with either aryl boronic acids or alkali metal boron-containing salts using pressure conditions that ranged from atmospheric to 680 bar and temperatures that ranged from 20 to 65 °C. Significantly, the pressure-induced losses in viscosity and, to a somewhat lesser extent, the concomitant pressure-induced 11B NMR spectral changes were found to be reversed upon lowering the pressure. |
| Databáze: | OpenAIRE |
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