Fabrication of large-scale, flexible, and robust superhydrophobic composite films using hydrophobic fumed silica nanoparticles and polydimethylsiloxane

We propose a simple and cost-effective method to fabricate superhydrophobic films comprising a composite layer of polydimethylsiloxane (PDMS) and hydrophobic fumed silica nanoparticles on the top and a PDMS bonding layer at the base. The PDMS layer was coated onto a substrate by spray-coating while the composite layer was formed by compressing the silica nanoparticles into the PDMS layer via low vacuum conditions. The prepared film exhibited excellent superhydrophobicity with an apparent contact angle greater than 177° and a sliding angle of less than 2°. The robustness of the superhydrophobic film was evaluated through a mechanical durability test, chemical stability test, and long-term storage in the air. The test results showed good mechanical durability and stability due to a thick composite layer and good bonding among the materials. Additionally, the superhydrophobic films were coated with different shapes and were separated successfully from flat shapes and three-dimensional curved shapes with a release agent as the flexible films. These results demonstrated a facile fabrication process to generate robust superhydrophobic films with a large area and complex shapes for industrial applications such as drag reduction, anti-icing, anti-corrosion, and others.