Photo-induced transformation of wormlike micelles to spherical micelles in aqueous solution

A photo-responsive system composed of an imidazolium-type surfactant 1-hexadecyl-3-methylimidazolium bromide ([C 16 mim]Br) and a commonly photosensitive aromatic compound trans -cinnamic acid ( trans -CA) was studied through UV spectra, 1 H NMR, and rheological measurements. In aqueous solution, th...

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Bibliographic Details
Published inSoft matter Vol. 8; no. 3; pp. 7858 - 7864
Main Authors Li, Jun, Zhao, Mingwei, Zhou, Hongtao, Gao, Hejun, Zheng, Liqiang
Format Journal Article
LanguageEnglish
Published 01.01.2012
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Summary:A photo-responsive system composed of an imidazolium-type surfactant 1-hexadecyl-3-methylimidazolium bromide ([C 16 mim]Br) and a commonly photosensitive aromatic compound trans -cinnamic acid ( trans -CA) was studied through UV spectra, 1 H NMR, and rheological measurements. In aqueous solution, the compounds [C 16 mim]Br and trans -CA can self-assemble to form viscoelastic wormlike micelles. Through UV irradiation, the CA molecules exhibit molecular photoisomerization from trans - to cis -, which results in a change of the molecular critical packing. The wormlike micelles transform into spherical micelles after UV irradiation, which is also confirmed by rheological measurements. The possible mechanism of the phase transition for the photo-responsive [C 16 mim]Br-CA system. When CA is in its trans -state, the wormlike micelles are formed in the system. After the UV irradiation, the trans -isomer transforms to the cis -isomer. Then the spherical micelles are formed.
ISSN:1744-683X
1744-6848
DOI:10.1039/c2sm25218j