TY  - JOUR
A1  - Zakrevskyy, Yuriy
A1  - Richter, Marcel
A1  - Zakrevska, Svitlana
A1  - Lomadze, Nino
A1  - von Klitzing, Regine
A1  - Santer, Svetlana
T1  - Light-controlled reversible manipulation of microgel particle size using azobenzene-containing surfactant
JF  - Advanced functional materials
N2  - 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.
Y1  - 2012
U6  - https://doi.org/10.1002/adfm.201200617
SN  - 1616-301X
VL  - 22
IS  - 23
SP  - 5000
EP  - 5009
PB  - Wiley-VCH
CY  - Weinheim
ER  -