A single-component photorheological fluid with light-responsive viscosity.
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Kelly, E. A., Fox, N., Houston, J. E., Blayo, C., Divitini, G., Cowieson, N., Daly, R., & et al. (2020). A single-component photorheological fluid with light-responsive viscosity.. Nanoscale, 12 (11), 6300-6306. https://doi.org/10.1039/c9nr10350c
Viscoelastic fluids whose rheological properties are tunable with light have the potential to deliver significant impact in fields relying on a change in flow behavior, such as in-use tuning of combined efficient heat-transfer and drag-reduction agents, microfluidic flow and controlled encapsulation and release. However, simple, single-component systems must be developed to allow integration with these applications. Here, we report a single-component viscoelastic fluid, capable of a dramatic light-sensitive rheological response, from a neutral azobenzene photosurfactant, 4-hexyl-4'butyloxymonotetraethylene glycol (C6AzoOC4E4) in water. From cryo-transmission electron microscopy (TEM), small-angle X-ray scattering (SAXS) and rheology measurements, we observe that the photosurfactant forms an entangled network of wormlike micelles in water, with a high viscosity (28 Pa s) and viscoelastic behaviour. UV irradiation of the surfactant solution creates a less dense micellar network, with some vesicle formation. As a result, the solution viscosity is reduced by four orders of magnitude (to 1.2 × 10-3 Pa s). This process is reversible and the high and low viscosity states can be cycled several times, through alternating UV and blue light irradiation.
Is supplemented by: https://doi.org/10.17863/CAM.56682
European Commission Horizon 2020 (H2020) Research Infrastructures (RI) (823717)
External DOI: https://doi.org/10.1039/c9nr10350c
This record's URL: https://www.repository.cam.ac.uk/handle/1810/308902
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