Durable Superhydrophobic Particles Mimicking Leafhopper Surface: Superoleophilicity and Very Low Surface Energy

Abstract

The powder coating on brochosomes of leafhopper can repel water, diiodomethane (DM), and ethylene glycol (EG) droplets with contact angle >150°. This is attributed to the very low surface energy as low as <1.0 mN m–1 and their porous honeycomb structure. In this work, grafted silica nanoparticles with properties similar to leafhopper (LH) particle coating is synthesized in a single step by catalytic grafting of stearic acid on nonporous silica nanoparticles. The particles repel water, diiodomethane, and ethylene glycol with contact angle 167°, 161°, and 157°, respectively. The surface energy is also found as <1.0 mN m–1. The particle coating shows sliding angle <10° with these probe liquids. The superhydrophobic particles are resistant to pH = 1 to 13, boiling water conditions and preserves super-repelling nature to reference liquids after the treatments. In a mixture of hexane/water or kerosene/water, the particles completely wet the oleophilic part and repel water layer due to superoleophilic–superhydro...