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Photochromism of Amphiphilic Dithienylethenes as Langmuir–Schaefer Films

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journal contribution
posted on 19.08.2018, 00:00 by Andreas K. Rossos, Maria Katsiaflaka, Jianxin Cai, Sean M. Myers, Elena Koenig, Robert Bücker, Sercan Keskin, Günther Kassier, Régis Y. N. Gengler, R. J. Dwayne Miller, R. Scott Murphy
Surface pressure–area isotherms were recorded under different irradiation conditions for single-component Langmuir films of three photochromic amphiphilic dithienylethenes. Nonirradiated films of these photochromic amphiphiles were mechanically stable. In addition, a shift of the isotherms to larger mean molecular areas was observed for films prepared from UV-light-irradiated dithienylethenes. Unexpectedly, a significant expansion was observed for a film prepared from visible-light-irradiated dithienylethene incorporating large branched alkyl chains. Upon further study, atomic force microscopy and transmission electron microscopy images of Langmuir–Schaefer films revealed that this pronged dialkyl derivative undergoes a photoinduced change in morphology, as circular aggregates coalesce into larger continuous aggregated structures. Nevertheless, its photoisomerization was completely reversible as single-component multilayer thin films upon direct UV or visible light irradiation.