Wide-temperature antifouling characteristic of a double re-entrant pillar array surface

Fouling causes numerous adverse effects on various types of systems. In addition, clean fouling on a solid surface is cost-intensive and time-consuming. Superhydrophobic (SHB) surfaces with a water-repellent property can potentially be used for antifouling. However, SHB surfaces lose their antifouling property at high temperatures because of the failure of the hydrophobic coating on them. Nevertheless, there are numerous applications being operated at high temperatures. Thus, a surface exhibiting antifouling characteristic over a wide temperature range is required. In this study, we demonstrate that a double re-entrant pillar (DRP) array surface possesses a wide-temperature antifouling characteristic. Although the silicon dioxide top surface of the pillar is hydrophilic, the upward surface tension force from the DRPs prevents the impacting droplets from penetrating the pillar array. Thus, the impacting droplets bounce back from the surface without leaving residues on it at temperatures from 25 to 560°C. By contrast, the impurities of the impacting droplets are retained on an SHB surface composed of a silicon nanowire array at various temperatures. The wide-temperature antifouling property of the DRP surface can be used for preventing fouling in many industrial systems.