Reversibly switchable wettability on aluminum alloy substrate corresponding to different pH droplet and its corrosion resistance

• We have prepared a pH-responsive surface.
• Special wettability was achieved on this surface under different pH conditions.
• The response mechanism relies on the protonation/deprotonation of the carboxy groups.
• The superhydrophobic surface with low adhesion exhibits self-cleaning ability.
• The superhydrophobic surface also presents excellent corrosion resistance.

A facile approach is presented in this paper on fabricating a special surface whose wettability can switch reversibly between superhydrophobicty and superhydrophilicity. The approach includes anodic oxidation, gold layer spraying and thiols modification. After modified by the mixed thiol solution, the contact angle of the surface transits sharply from about 160° to 0°, that is to say, from superhydrophobic state to superhydrophilic state, as the pH of the droplet increases from 7 to 12. The approach is versatile enough to play either solid surface. In addition, the as-prepared surface modified with 1 mmol·L−1 HS(CH2)11CH3 was proved to be superhydrophobic with low adhesion and exhibited good corrosion resistance property compared with the untreated substrate and anodized sample in the 3.5 wt% NaCl solution. It may provide a new method to improve the anticorrosion of the aluminum alloys.

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