Durability of hydrophobic coatings for superhydrophobic aluminum oxide

1. Applied Surface Science 282 (2013) 73– 76 Durability of hydrophobic coatings for superhydrophobic aluminum oxide Elliot Jennera a, Charlotte Barbierb b, Brian D’Ursoa a,∗ a Department of Physics & Astronomy, University of Pittsburgh, Pittsburgh, PA 15260, United States b Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States Paper Survey Advisor : Cheng-Hsin Chuang Advisee ﹕Wen-Yu Lee Institute of Mechanical Engineering Date ﹕2013/10/24

2. Material and methods – Fabrication • Anodization parameters: • Anodization: 320 V, 0.051 A/m2 at 18-20 ̊C, 0.1175 M Citric acid • Pore widening etching: 2 wt% Tetramethylammonium hydroxide (TMAH) at 18 ̊C 750nm Fig. 1. SEM image of a spiked PAA surface in cross section at 20◦ inclination, thickness 4um. Note the visible steps made by alternation of 8 anodization and 7 etching steps. • Hydrophobic fluoropolymer: • Solvey Plastics Hyflon AD-60

3. Material and methods – Experimental method • F0~F5: Baked for 15 min at 150 ̊C • After baked: • F3: Spin coated at 1000rpm with 2wt% Hyflonin 3M Fluorinert(FC-40) • F5: Spin coated with PGMEA:HMDS in 4:1 solution at 4000rpm→ Followed by F3 Hyflon solution

4. Results and discussion 161o±1 Fig. 2. Profile image showing contact angle of a drop of water on the material before full immersion in water was undertaken. Drop is held in place with a needle suspended above the surface. Fig. 3. Rolling angle as a function of time. A reading of 90◦ indicates the drop adhered up to or past vertical tilt.

5. Results and discussion AAO Sample Edge Fig. 4. SEM images of samples, taken at a 20◦ angle after testing and cracked to show profile.

6. Thanks for your attention!