Flexible superhydrophobic gold film for magnetical manipulation of droplets

Herein, we present a simple, efficient, and economical approach for the preparation of superhydrophobic gold film embedded on polydimethylsiloxane (PDMS) sheets without the requirement of surface pretreatment. The reduction reaction between chloroauric acid (HAuCl4) and sodium formate (HCOONa) at room temperature was performed to generate the aggregated gold microstructures on a PDMS sheet without chemical residuals. Superhydrophobic property was achieved when deposition time was reached to 2 h with water contact angle >160 degrees and low contact angle hysteresis (H = 1.93 degrees). Systematic investigations of the size, morphology, and mechanism of the generated gold films are presented. The generated gold film contains two different layers involving uniform spherical gold particles attached to the PDMS surface with the complex hierarchical structures on top. The complex structures play an important role in the superhydrophobic property, as they strongly promote the roughness to the PDMS surface. The durability of the fabricated gold film was elucidated by dropping similar to 7,200 waterdrops and external physical forces (e.g. stretch, bend, and twist). The main structures and their superhydrophobic properties have not disoriented after the tests. Moreover, the surface of the gold film demonstrated the potential applications as magnetical manipulation of droplets and a robust Surface enhanced Raman spectroscopy (SERS substrate). (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A simple, efficient, and economical method was presented to prepare superhydrophobic gold film embedded on PDMS sheets without surface pretreatment. Systematic investigations revealed that the generated gold film contains uniform spherical gold particles with complex hierarchical structures, which play a crucial role in the superhydrophobic property. The durability of the fabricated gold film was demonstrated by various tests, showing no disorientation in the main structures and their superhydrophobic properties.