A robust, flexible superhydrophobic sheet fabricated by in situ growth of micro-nano-SiO2 particles from cured silicone rubber

Here, we report a multifunctional superhydrophobic material achieved through the in situ growth of micro-nano-SiO2 particles from the surface of a preswollen silicone rubber sheet by sol–gel methods. The contact angles of the sheets reached 162°. The scanning electron microscopy (SEM) photographs showed that 0.8–1 μm SiO2 microspheres grew in situ on the surface of the silicone rubber sheets. The microspheres had 30–70 nm nanoscale bulges on their surfaces that formed micro-nano-structures, like a “lotus leaf”. The sizes of the micro-SiO2 particles and nanobulges were both controllable. The superhydrophobic sheets showed excellent water repellency and self-cleaning performance and exhibited satisfactory durability against mechanical abrasion, rubbing, bending, and long-term underwater storage. The mechanical robustness was attributed to a thick micro-nano-SiO2 layer formed on the surface instead of a monolayer hydrophobic coating. The superhydrophobic rubber sheets were not fluorinated, demonstrated robustness and elasticity, were easy to prepare, and were expected to provide unique advantages for a wide range of applications in biomedicine, energy and electronic devices.