Effect of self-affine fractal characteristics of surfaces on wetting

In this letter, we show experimentally that the wetting property of a solid surface crucially depends on the surface morphological parameters such as; (1) root mean square (rms) roughness σ , (2) in-plane roughness correlation length ξ , and (3) roughness exponent α of the self-affine surface. We have shown that the contact angle monotonically decreases with the increase in the rms local surface slope ρ ( ∝ σ / ξ α ) . We have shown that the same solid surface can be made hydrophobic or hydrophilic by merely tuning these self-affine surface morphological parameters.