- Title
- Silica particle stability and settling in protic ionic liquids
- Creator
- Smith, Jacob; Webber, Grant B.; Warr, Gregory G.; Atkin, Rob
- Relation
- Langmuir Vol. 30, Issue 6, p. 1506-1513
- Publisher Link
- http://dx.doi.org/10.1021/la403978b
- Publisher
- American Chemical Society (ACS)
- Resource Type
- journal article
- Date
- 2014
- Description
- Silica particle suspensions of 10 wt % have been investigated in the protic ionic liquids (ILs) ethylammonium nitrate (EAN), ethanolammonium nitrate (EtAN), propylammonium nitrate (PAN), and dimethylethylammonium formate (DMEAF). Static and dynamic light scattering reveal that single particles coexist in dynamic equilibrium with flocculated networks at room temperature. These types of systems are classified as weakly flocculated and are quite rare. As weakly flocculated systems generally exist only within a narrow range of conditions, the effect of temperature was probed. When temperature is increased, the thermal motion of suspended particles increases, favoring dispersion, but in ILs suspensions, heating reduces the stabilizing effect of the interfacial structure of the IL. When subjected to a small increase in temperature, particle suspensions in ILs become unstable, indicated by the absence of a peak corresponding to single particles in the light scattering data. For EAN and DMEAF, further increasing temperatures above 40 °C returns the systems to a weakly flocculated state in which thermal energy is sufficient to break particles away from aggregates. Weakly flocculated suspensions in EAN and EtAN settle more rapidly than predicted by the Stokes equation, as the particles spend a significant portion of time in large, rapidly settling flocs. Surprisingly, suspensions in PAN and DMEAF settle slower than predicted. Oscillatory rheology indicates that these suspensions are viscoelastic, due to a persistent, long-range structure in the suspension that slows settling. In aggregated systems, settling is very rapid.
- Subject
- ionic liquids; ethanolammonium nitrate; silica particle stability; weakly flocculated systems
- Identifier
- http://hdl.handle.net/1959.13/1041241
- Identifier
- uon:13886
- Identifier
- ISSN:0743-7463
- Rights
- This document is the Accepted Manuscript version of a Published Work that appeared in final form in Langmuir, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://dx.doi.org/10.1021/la403978b
- Language
- eng
- Full Text
- Reviewed
- Hits: 1770
- Visitors: 2197
- Downloads: 455
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | ATTACHMENT02 | Author final version | 397 KB | Adobe Acrobat PDF | View Details Download |