Reversible Light-Induced Morphological Change in Langmuir-Blodgett Films

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• 作者：Mutsuyoshi Matsumoto ; Daisuke Miyazaki ; Motoo Tanaka ; Reiko Azumi ; Eiichiro Manda ; Yukishige Kondo ; Norio Yoshino ; and Hiroaki Tachibana
• 刊名：Journal of the American Chemical Society
• 出版年：1998
• 出版时间：February 25, 1998
• 年：1998
• 卷：120
• 期：7
• 页码：1479 - 1484
• 全文大小：267K
• 年卷期：v.120,no.7(February 25, 1998)
• ISSN：1520-5126

文摘

An amphiphilic anionic azobenzene derivative, soluble in water,formed a monolayer on an aqueoussubphase containing a water-soluble polycation. The monolayerswere transferred onto solid substrate by theLangmuir-Blodgett (LB) technique. XPS measurements showed thation exchange reaction proceeded almostcompletely at the air-water interface and that the ratio of themonomer unit of the polycation to the azobenzenewas almost unity. UV/vis absorption and IR measurements indicatedthat the azobenzene photoisomerizedreversibly in the LB films on alternate illumination with UV and vislight. Furthermore, a reversiblemorphological change induced by light was observed in the LB films withAFM. Before illumination, thesurface of the single-layer LB film was very smooth with a surfaceundulation of less than 1 nm. On illuminationwith UV light, however, a number of hills, with the height of ca. 5 nmand the diameter of the base of ca. 100nm, appeared on the film surface. These structures almostdisappeared on illumination with vis light. Thisindicates that the widely accepted assumption that photoisomerizationshould not change the two-dimensionalstructures significantly does not hold in the presentcase.