Fabrication of superhydrophobic surfaces inspired by “stomata effect” of plant leaves via swelling-vesiculating-cracking method

Abstract

Fabrication of superhydrophobic surfaces by simple techniques is of significant interest. Herein, inspired by the “stomata effect” of plant leaves, a superhydrophobic surface with bionic stomata randomly on polydimethylsiloxane (PDMS) is fabricated by a facile swelling-vesiculating-cracking method. Neither multistep modification of nanostructure nor introduction of low surface energy substance is carried out during the fabrication. The water contact angle (CA) of the bio-inspired superhydrophobic surfaces with stomata-like structures (BSSS) can reach 168.4 ± 1° with 8.9° sliding angle and less than 10° contact angle hysteresis (CAH). The structure and wettability of the BSSS are characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive spectrometry and X-ray photoelectron spectroscopy. The effects of swelling ratio, heat treatment temperature and surface morphology on the hydrophobicity of the BSSS are investigated systematically. Noticeably, the BSSS are provided with wonderful durability in organic solvents, ice water, and strong acid solution. Furthermore, a theoretical model for BSSS based on the Cassie-Baxter relation is established to elucidate the “stomata effect”. The model reveals that the water contact angle will reach 180° when the stomata-like structure is suitable. The fabrication of BSSS provides a potential strategy for the development of novel superhydrophobic materials.