High Photoinduced Ordering and Controllable Photo-Stability of Hydrophilic Azobenzene Material Based on Relative Humidity

Azobenzene materials provide an effective way for liquid crystal (LC) alignment besides traditional rubbing technology. A strong relationship between relative humidity (RH) and the photoalignment quality of hydrophilic azobenzene dye brilliant yellow (BY) has been investigated. Good photoalignment q...

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Veröffentlicht in:Langmuir 2018-03
Hauptverfasser: Shi, Yue, Zhao, Chenxiang, Ho, Jacob Yeuk-Lung, Song, Feng, Chigrinov, Vladimir G, Luo, Dan, Kwok, Hoi Sing, Sun, Xiao Wei
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Sprache:eng
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Zusammenfassung:Azobenzene materials provide an effective way for liquid crystal (LC) alignment besides traditional rubbing technology. A strong relationship between relative humidity (RH) and the photoalignment quality of hydrophilic azobenzene dye brilliant yellow (BY) has been investigated. Good photoalignment quality can only be ensured at about 40% RH or below. On the other hand, the photo-stability of the alignment layer is also influenced dramatically by RH. The rewritability can be guaranteed at extremely low RH (≤ 10%). It is gradually lost with increasing RH, and the alignment layer becomes photo-stable against further light exposure when at 40% RH or above. Therefore, the BY photoalignment layer can be tuned from rewritable to photo-stable by simply adjusting RH, and thus multi-step photo-patterned alignments can be obtained and reserved based on this method. Similar properties are also expected for other hydrophilic azobenzene photoalignment materials, where the specific RH values may vary correspondingly. The reason is due to the strong intermolecular interaction and J-aggregate formation of BY molecules with water insertion. Moreover, the lyotropic LC formed by J-aggregated BY molecules in aqueous solution is reported here.
ISSN:1520-5827