Bouncing Droplets: A Hands-On Activity To Demonstrate the Properties and Applications of Superhydrophobic Surface Coatings

Abstract

Here we report a hands-on activity addressed to master’s students in Physical Chemistry and Materials Science courses on the properties and applications of superhydrophobic surfaces. This simple and intuitive experience can also be used to teach undergraduate and high school students, thanks to its application-oriented approach and tangible results. Superhydrophobicity was achieved by the functionalization of oxide powders with alkylsilanes and their subsequent deposition on a glass substrate. The film’s superhydrophobicity was assessed by different application tests and compared with the behaviors of model hydrophobic, hydrophilic, and superhydrophilic surfaces. Its antistain properties were tested with both model dye solutions and everyday liquids. Films were fouled with graphite and dye powders to compare the self-cleaning capabilities of the different surfaces, and single droplet transport was achieved by adding magnetic particles. This engaging and adaptable experience introduces students to basic concepts of surface science in an intuitive and tangible way.