Sequential Evaporation–Induced Formation of Polymeric Surface Microdents via Ouzo Effect

Microdents fabricated on solid substrates have numerous applications, such as containers for cell growth, reactors for chemical reactions, and nucleation sites for growing photonic crystals. In this study, a new method is developed to fabricate microdents on polystyrene (PS) film deposited on a solid surface. The process relied on Ouzo effect in a ternary solution consisting of three solvents exhibiting different volatilities. In the ternary solution, precursor water droplets are first nucleated when a good solvent of water evaporated. The nucleated water droplets then act as templates for microdent formation during PS film deposition. After water droplets eventually evaporates, microdents are generated on the PS film. The detailed process of microdent formation is experimentally revealed. By controlling the nucleation of water droplets and PS concentration, the lateral size and the depth of microdents are systematically tuned. Moreover, it is demonstrated that the microdent decorated films obtained with the proposed method can be used to fabricate lubricating surfaces, which exhibit a low contact angle hysteresis of 2 degrees.