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Thermally responsive capillary suspensions

Das, Anupam A.K.; Dunstan, Timothy S.; Stoyanov, Simeon D.; Starck, Pierre; Paunov, Vesselin N.

Authors

Anupam A.K. Das

Timothy S. Dunstan

Simeon D. Stoyanov

Pierre Starck

Vesselin N. Paunov



Contributors

Vesselin Paunov
Producer

Abstract

© 2017 American Chemical Society. 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.

Citation

Das, A. A., Dunstan, T. S., Stoyanov, S. D., Starck, P., & Paunov, V. N. (2017). Thermally responsive capillary suspensions. ACS Applied Materials & Interfaces, 9(50), 44152-44160. https://doi.org/10.1021/acsami.7b11358

Journal Article Type Article
Acceptance Date Nov 22, 2017
Online Publication Date Dec 6, 2017
Publication Date Dec 20, 2017
Deposit Date Feb 7, 2018
Publicly Available Date Dec 7, 2018
Journal ACS Applied Materials and Interfaces
Print ISSN 1944-8244
Electronic ISSN 1944-8252
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 9
Issue 50
Pages 44152-44160
DOI https://doi.org/10.1021/acsami.7b11358
Keywords General Materials Science
Public URL https://hull-repository.worktribe.com/output/585065
Publisher URL https://pubs.acs.org/doi/10.1021/acsami.7b11358

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