Synthesis of superhydrophobic surfaces with Wenzel and Cassie-Baxter state: experimental evidence and theoretical insight

We demonstrate surfactant- and template-free synthesis of superhydrophobic thin films by controlling surface morphology. The surface morphology evolution process was determined from time-dependent studies. The relationships between the water contact angle, sliding angle, water droplet size, and surface microstructures were investigated. It is found that structural parameters play an important role in determining the adhesion of a droplet on superhydrophobic surfaces and the liquid-solid adhesion can be effectively manipulated through tailoring the morphology or the size of the microstructures on the surface. We provide a theoretical explanation for the Cassie-Baxter state (water rolls) and the Wenzel state (sticky surface, water adheres) with droplet size on different microstructure surfaces. The new theoretical insight provided in this study matches well with experimental results.