Photoreactive composite coating with composition dependent wetting properties

• Main Authors: L. Merai, A. Deak, D. Sebok, E. Csapo, T. S. Kolumban, B. Hopp, I. Dekany, L. Janovak
• Format: Article
• Language: English
• Published: Budapest University of Technology 2018-12-01
• Series: eXPRESS Polymer Letters
• Subjects: Polymer composites; Coatings; Nanomaterials; Surface roughness; Adjustable wetting
• Online Access: http://www.expresspolymlett.com/letolt.php?file=EPL-0009283&mi=cd

Photoreactive composite thin layers with tunable wetting properties from superhydrophilic to superhydrophobic nature were prepared. To achieve extreme wetting properties, the adequate surface roughness is a crucial factor, which was achieved by the incorporation of plasmonic Ag-TiO2 particles, as polymer filler, into the smooth polymer film with adjusted hydrophilicity. The initial copolymer films were synthesized from hydrophilic 2-hydroxyethyl-acrylate (HEA) and hydrophobic perfluorodecyl-acrylate (PFDAc) monomers. In the case of hydrophobic PFDAc, the photocatalyst- roughened thin films displayed superhydrophobic behavior (γstot ~ 2.3±1.7 mJ/m2, Θ > 150°), while the roughened hydrophilic pHEA layers possessed superhydrophilicity (γstot ~ 72.1 ±0.2 mJ/m2, Θ ~ 0°). The photoactivity of the composites was presented both in solid/gas (S/G) and solid/ liquid (S/L) interfaces. According to the light-emitting diode (LED) light photodegradation tests on ethanol (EtOH) as volatile organic compound (VOC) model- molecules at the S/L interface, the superhydrophobic hybrid layer was photooxidized 88.3% of the initial EtOH (0.36 mM). At S/L interface the photocatalytic efficiency was depended on the polarity of the model pollutant molecules: the photooxidation of hydrophobic SUDAN IV (c0 = 0.25 mg/mL) dye reached 80%, while in the case of the hydrophilic Methylene Blue dye (c0 = 0.002 mg/mL) it was only 17.3% after 90 min blue LED light (λ = 405 nm) illumination.