Mechanically tunable single-component soft polydimethylsiloxane (PDMS)-based robust and sticky superhydrophobic surfaces

In this letter, we report the fabrication of robust and mechanically tunable superhydrophobic surfaces based on elastic wrinkles having bi-modal distribution of roughness. Contrary to most superhydrophobic surfaces, where different nano- and/or micro-scale materials are used to create hierarchical roughness, we create them in the same material as of the substrate. Primary roughness is due to the micron-sized one-dimensional wrinkles while a nanoscale secondary roughness is created on top of the wrinkles using replica molding through a nano-master. Due to the elastic nature of the underneath polymer, polydimethylsiloxane (PDMS), the fabricated superhydrophobic wrinkles demonstrate mechanically tunable wetting behavior between superhydrophobic and hydrophobic states. Water drops depict sticky superhydrophobic behavior on the fabricated samples as they show the Cassie impregnated state corresponding to the Petal effect.