UV- resistent fluorinated coating for anodizated titanium surfaces

UV-resistant amorphous fluorinated coating for anodized titanium surfaces Presenting: Wu Menghua*‡,Walter Navarrini‡, Maria Vittoria Diamanti‡, Maurizio Sansotera‡, Federico Persico‡, Luca Magagnin‡, Stefano Radice§ ‡: Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano, via Mancinelli 7, 20131,Milano,Italy. E-mail:menghua.wu@mail.polimi.it §: Solvay Solexis, Research & Technology, Viale Lombardia 20, 20021, Bollate (MI), Italy. Abstract A high molecular weight copolymer of tetrafluoroethylene and perfluoro-4-trifluoromethoxy-1,3-dioxole (Hyflon® AD60), and two perfluoropolyether containing ammonium phosphate or triethoxysilane functionalities, Fluorolink® F10 and Fluorolink® S10 respectively, have been evaluated as protective coatings that can be easily applied on anodized titanium surfaces. Based on CIELab model, spectrophotometric analysis have been made to quantify chromatic variations of substrates after the application of fluorinated coatings. Water and n-dodecane contact angle measurements have been done by using the sessile drop method for both bare and coated surfaces in order to determine the hydrophobic and oleophobic properties of the coatings. The UV-stability of coatings have been studied by observing the variation of water contact angles and by FT-IR analyses on coated substrates before and after UV irradiation at regular time intervals. The thickness of the fluorinated films have been measured by ellipsometry and by weight evaluation. Preliminary adhesion test between films and substrate as well as their soiling resistance with castor oil have been investigated. Among the above three fluorinated polymers, we observed that the high Tg amorphous transparent Hyflon® AD60 revealed a good adhesion on the anodized titanium substrate, no evident modification of the sample original color, and in addition it conferred both hydrophobicity and oleophobicity to the substrate, more over resulted in a good UV resistance. 0,01 0,02 0,03 0,04 0,05 0,06 0,07 0,08 0,09 0,10 0,11 0,12 0,13 0,14 0,15Absorbance 1100 1200 1300 1400 1500 1600 Wavenumbers (cm-1) Fig. 1 Water-droplets on Hyflon® AD60 coated and on uncoated anodized titanium surfaces. Fig. 2 Constant IR absorbance of Hyflon® AD60 coating on anodized titanium