Tuning wettability and getting superhydrophobic surface by controlling surface roughness with well-designed microstructures

摘要

We proposed a method to tune the wettability of a solid surface by changing its roughness. With specific designed micro square-pillar arrays, the apparent contact angle of a hydrophobic surface can be continuously adjusted from the intrinsic contact angle above. The samples were fabricated by combining silicon micromachining and self-assembled monolayer modification. The experimental results were closer to Cassie's theoretical predictions on the super-hydrophobic surfaces than that by Wenzel's. With the same contact angle (CA, 110/spl deg/) on the flat surface, the apparent CAs can be tuned from 110/spl deg/ to nearly 180/spl deg/. The largest apparent CA can be up to 173/spl deg/, with pillars of 9.08/spl mu/m /spl times/ 9.08/spl mu/m /spl times/ 16/spl mu/m ( width /spl times/ width /spl times/ height ) and the spacing of 31.61/spl mu/m.