Fine control of the Wettability transition temperature of colloidal-crystal films: From superhydrophilic to superhydrophobic

A facile strategy for finely controlling the wettability transition temperature of colloidal-crystal films from superhydrophilic (water contact angle, CA, 0 degrees) to superhydrophobic (water CA, 150.5 degrees) is demonstrated. The colloidal-crystal films are assembled from poly(styrene-n-butyl acrylate-acrylic acid) amphiphilic latex spheres. The wettability transition temperature of the films can be well tuned by adjusting the n-butyl acrylate/styrene balance of the latex spheres. Superhydrophobic films are achieved when assembled at 90, 80, 70, 60, 40, or even 20 degrees C. This approach offers the flexibility of fabricating colloidal crystals with desired and tunable wettability, and can be further extended to general materials, opening up new perspectives in controlling the wettability behavior by chemical composition.