Fabrication and characterization of the hierarchical structure for superhydrophobicity and self-cleaning.

Hierarchical roughness is beneficial for the superhydrophobicity. Surfaces with microstructure, nanostructure and hierarchical structure were fabricated by replication of micropattern and self-assembly of hydrophobic alkanes. The fabrication technique used is a low-cost two-step process, which provides flexibility in fabrication of variety of hierarchical structures. Fabricated structures and surface chemistry mimic the hierarchical surfaces of superhydrophobic and self-cleaning plant surfaces. The influence of structure on the superhydrophobicity at different length scales is demonstrated by investigation of contact angle, contact angle hysteresis, droplet evaporation and propensity of the air pocket formation as well as adhesive forces.