Superhydrophobic lotus-leaf-like surface made from reduced graphene oxide through soft-lithographic duplication

In this work, reduced graphene oxide (RGO) was used as a material to fabricate superhydrophobic lotus-leaf-like surfaces through soft-lithographic duplication. In the process, a polydimethylsiloxane (PDMS) stamp was prepared by replica molding against the surfaces of fresh lotus leaves that functioned as masters. A dispersion of octadecylamine-modified reduced graphene oxide (ODA-RGO) in tetrahydrofuran (THF) was used as "ink". The lotus-leaf-like surfaces were fabricated by microcontact printing on the solid substrates. The results showed that due to the good processibility of the ODA-RGO dispersion, the printed layers display papillary micro/nano-structures with high fidelity to the surfaces of lotus leaves. The RGO-based lotus-leaf-like surfaces possess superhydrophobic characteristics with a water contact angle larger than 160° and the contact angle hysteresis less than 5°. Due to the excellent chemical stability of the RGO sheets, as-prepared surfaces show remarkable superhydrophobic stability. The lotus-leaf-like surfaces maintain the superhydrophobicity after heating treatment at 150 °C for 24 h or being exposed to corrosive solutions with different pH values for 12 h. The present findings prove that the RGO-based material is an ideal candidate for fabrication of environment-durable lotus-leaf-like surfaces, which can be expected to have applications in different areas.