Thermally Responsive Capillary Suspensions
| Autor: | Timothy S. Dunstan, Vesselin N. Paunov, Simeon D. Stoyanov, Pierre Starck, Anupam A. K. Das |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2017 |
| Předmět: |
Materials science
02 engineering and technology methyl cellulose 010402 general chemistry 01 natural sciences Suspension (chemistry) chemistry.chemical_compound Viscosity Rheology Phase (matter) thermally responsive hydrogels General Materials Science calcium carbonate capillary structuring VLAG Aqueous solution Aqueous two-phase system 021001 nanoscience & nanotechnology Silicone oil 0104 chemical sciences chemistry Chemical engineering Methyl cellulose capillary suspension 0210 nano-technology Physical Chemistry and Soft Matter agarose |
| Zdroj: | ACS Applied Materials and Interfaces 9 (2017) 50 ACS Applied Materials and Interfaces, 9(50), 44152-44160 |
| ISSN: | 1944-8244 |
| Popis: | We demonstrate that stimulus-responsive capillary-structured materials can be formed from hydrophobized calcium carbonate particles suspended in a non-polar phase (silicone oil) and bridged by very small amounts of a hydrogel as the secondary aqueous phase. Inclusion of thermally responsive polymers into the aqueous phase yielded a capillary-structured suspension whose rheology is controlled by a change in temperature and can increase its complex modulus by several orders of magnitude because of the gelation of the capillary bridges between the solid particles. We demonstrate that the rheology of the capillary suspension and its response upon temperature changes can be controlled by the gelling properties as little as 0.1 w/w % of the secondary aqueous phase containing 2 wt % of the gelling carbohydrate. Doping the secondary (aqueous) phase with methyl cellulose, which gels at elevated temperatures, gave capillary-structured materials whose viscosity and structural strength can increase by several orders of magnitude as the temperature is increased past the gelling temperature of the methyl cellulose solution. Increasing the methyl cellulose concentration from 0 to 2 w/w % in the secondary (aqueous) phase increases the complex modulus and the yield stress of the capillary suspension of 10 w/w % hydrophobized calcium carbonate in silicone oil by 2 orders of magnitude at a fixed temperature. By using an aqueous solution of a low melting point agarose as a secondary liquid phase, which melts as the temperature is raised, we produced capillary-structured materials whose viscosity and structural strength can decrease by several orders of magnitude as the temperature is increased past the melting temperature of the agarose solution. The development of thermally responsive capillary suspensions can find potential applications in structuring of smart home and personal care products as well as in temperature-triggered change in rheology and release of flavors in foods and actives in pharmaceutical formulations. |
| Databáze: | OpenAIRE |
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