Using Pencil Drawing To Pattern Robust Superhydrophobic Surfaces To Control the Mobility of Water Droplets

For centuries, pencils have been convenient implements for writing, drawing, and portraying. In this study, we found another use for the lowly pencil: to modulate the mobility of water droplets on a robust superhydrophobic surface. Here, we describe a simple method for fabricating durable superhydrophobic films from carbon nanotube (CNT)/polybenzoxazine coatings. These as-prepared coatings possessed robust superhydrophobicity with strong adhesion to glass and metal substrates. We achieved tunable water droplet mobility on the superhydrophobic surface with patterned wettability after drawing with a pencil. The mobility could be switched rapidly (within 1 min) between the poorly adhesive rolling state and the highly adhesive pinning state through sequential pencil drawing and sonication processes.