Poly(azobenzene acrylate-co-fluorinated acrylate) Spin-Coated Films: Influence of the Composition on the Photo-Controlled Wettability

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• 作者：Sanae Abrakhi ; S茅bastien P茅ralta ; Odile Fichet ; Dominique Teyssi茅 ; Sophie Cantin
• 刊名：Langmuir
• 出版年：2013
• 出版时间：July 30, 2013
• 年：2013
• 卷：29
• 期：30
• 页码：9499-9509
• 全文大小：475K
• 年卷期：v.29,no.30(July 30, 2013)
• ISSN：1520-5827

文摘

The wetting properties of spin-coated films of copolymers based on azobenzene and fluorinated units have been investigated. The copolymers, denoted as poly(Azo-co-AcRf6), have been synthesized by free-radical polymerization of different proportions of acrylate monomers bearing either an azobenzene group or a semifluorinated side chain. The UV鈥搗isible spectroscopy analysis of the different spin-coating films through a cycle of UV and visible light irradiation indicates the reversible trans鈥?i>cis isomerization of azobenzene groups. Simultaneously, atomic force microscopy shows that surface roughness does not exceed 1 nm. Advancing and receding contact angles of water and diiodomethane have been measured before and after UV photoirradiation of the different surfaces. In particular, a decrease in the advancing contact angles has been observed upon trans鈥?i>cis isomerization of azobenzene groups. Switching variations up to 50掳 have been evidenced without any introduction of surface nanoroughness. Surface free-energy evaluations have been deduced from these measurements, including dispersive and polar components. The results show that, through surface composition and UV photoirradiation, a large range of surface free-energies can be obtained, from 7 to 46 mN路m^鈥?.