Reversible wettability of photoresponsive fluorine-containing azobenzene polymer in Langmuir-Blodgett films

Citation
Cl. Feng et al., Reversible wettability of photoresponsive fluorine-containing azobenzene polymer in Langmuir-Blodgett films, LANGMUIR, 17(15), 2001, pp. 4593-4597
Citations number
26
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Journal title
LANGMUIR
ISSN journal
0743-7463 → ACNP
Volume
17
Issue
15
Year of publication
2001
Pages
4593 - 4597
Database
ISI
SICI code
0743-7463(20010724)17:15<4593:RWOPFA>2.0.ZU;2-A
Abstract
A polymer containing 3'-[trifluoromethyl-4,3'-dibenzoazo] dyes in the side chains has been synthesized, and a monolayer of this polymer has been trans ferred onto solid substrate by the Langmuir-Blodgett (LB) technique. The re versible processes of photoisomerization of the LB films induced by light a re observed by UV-vis absorption spectra, in situ atomic force microscopy, and friction force microscopy. In addition, the physisorbed monolayers of t he monomer of the polymer at liquid/solid interface are investigated by sca nning tunneling microscopy. The films of the polymer show the reversible ch ange of morphological and friction force responses under alternate UV(365 /- 10 nm) and visible (436 +/- 10 nm) irradiation. The films also undergo r eversible wettability changes with UV and visible light irradiation, which are directly confirmed by contact angle measurement. The largest photoinduc ed change of contact angle is 11 +/- 1 degrees. The larger value of the con tact angles measured corresponds to films mainly composed of the trans isom ers of the molecules. Evidence shows that the photoinduced surface energy c hanges have an important influence on the wettability changes.