Controlled growth of superhydrophobic films by sol-gel method on aluminum substrate

Superhydrophobic surface was prepared by sol-gel method on aluminum substrate via immersing the clean pure aluminum substrate into the solution of zinc nitrate hexahydrate (Zn(NO(3))(2) center dot 6H(2)O) and hexamethylenetetraamine (C(6)H(12)N(4)) at different molar ratios and unchanged 0.04 mol/L total concentration, then heated at 95 degrees C in water bath for 1.5h, subsequently modified with 18 alkanethiols or stearic acid. When the molar ratios of Zn(NO(3))(2) center dot 6H(2)O and C(6)H(12)N(4) were changed from 10:1 to 1:1 the contact angle was higher than 150 degrees. The best prepared surface had a high water contact angle of about 154.8 degrees, as well as low angle hysteresis of about 3 degrees. The surface of prepared films using Zn(NO(3))(2) center dot 6H(2)O and C(6)H(12)N(4) composed of ZnO and Zn-Al LDH, and Al. SEM images of the film showed that the resulting surface exhibits different. ower-shaped wurtzite zinc oxide microstructure and porous Zn-Al LDH. The special flowerlike and porous architecture, along with the low surface energy leads to the surface superhydrophobicity. (C) 2010 Elsevier B.V. All rights reserved.