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 SurveyAdvisor : Cheng-Hsin Chuang

Advisee Wen-Yu Lee﹕

Institute of Mechanical EngineeringDate 2013/10/24﹕

Applied Surface Science 282 (2013) 73– 76

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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.

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

Hydrophobic fluoropolymer: Solvey Plastics Hyflon AD-60

750nm

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Material and methods – Experimental method

F0~F5: Baked for 15 min at 150 <CAfter baked:• F3: Spin coated at 1000rpm with 2wt% Hyflon in 3M Fluorinert(FC-40)• F5: Spin coated with PGMEA:HMDS in 4:1 solution at 4000rpm

→ Followed by F3 Hyflon solution

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Fig. 3. Rolling angle as a function of time. A reading of 90◦ indicates the drop adhered up to or past vertical tilt.

Results and discussion

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.

161o±1

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Results and discussion

AAOSample

Edge

Fig. 4. SEM images of samples, taken at a 20◦ angle after testing and cracked to show profile.

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Thanks for your attention!