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Light-controlled reversible manipulation of microgel particle size using azobenzene-containing surfactant

  • The light-induced reversible switching of the swelling of microgel particles triggered by photo-isomerization and binding/unbinding of a photosensitive azobenzene-containing surfactant is reported. The interactions between the microgel (N-isopropylacrylamide, co-monomer: allyl acetic acid, crosslinker: N,N'-methylenebisacrylamide) and the surfactant are studied by UV-Vis spectroscopy, dynamic and electrophoretic light scattering measurements. Addition of the surfactant above a critical concentration leads to contraction/collapse of the microgel. UV light irradiation results in trans-cis isomerization of the azobenzene unit incorporated into the surfactant tail and causes an unbinding of the more hydrophilic cis isomer from the microgel and its reversible swelling. The reversible contraction can be realized by blue light irradiation that transfers the surfactant back to the more hydrophobic trans conformation, in which it binds to the microgel. The phase diagram of the surfactant-microgel interaction and transitions (aggregation,The light-induced reversible switching of the swelling of microgel particles triggered by photo-isomerization and binding/unbinding of a photosensitive azobenzene-containing surfactant is reported. The interactions between the microgel (N-isopropylacrylamide, co-monomer: allyl acetic acid, crosslinker: N,N'-methylenebisacrylamide) and the surfactant are studied by UV-Vis spectroscopy, dynamic and electrophoretic light scattering measurements. Addition of the surfactant above a critical concentration leads to contraction/collapse of the microgel. UV light irradiation results in trans-cis isomerization of the azobenzene unit incorporated into the surfactant tail and causes an unbinding of the more hydrophilic cis isomer from the microgel and its reversible swelling. The reversible contraction can be realized by blue light irradiation that transfers the surfactant back to the more hydrophobic trans conformation, in which it binds to the microgel. The phase diagram of the surfactant-microgel interaction and transitions (aggregation, contraction, and precipitation) is constructed and allows prediction of changes in the system when the concentration of one or both components is varied. Remote and reversible switching between different states can be realized by either UV or visible light irradiation.show moreshow less

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Metadaten
Author:Yuriy Zakrevskyy, Marcel Richter, Svitlana Zakrevska, Nino Lomadze, Regine von KlitzingORCiD, Svetlana SanterORCiDGND
DOI:https://doi.org/10.1002/adfm.201200617
ISSN:1616-301X (print)
Parent Title (English):Advanced functional materials
Publisher:Wiley-VCH
Place of publication:Weinheim
Document Type:Article
Language:English
Year of first Publication:2012
Year of Completion:2012
Release Date:2017/03/26
Volume:22
Issue:23
Pagenumber:10
First Page:5000
Last Page:5009
Funder:German Research Council [SPP 1259]; CoE "UniCat"; IGRTG [1524]
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie
Peer Review:Referiert