The stable superhydrophobic ZnO@stearic acid nanocone array and its remarkable all-sided protective abilities in various extreme environments

Abstract The ZnO-based devices are constantly taken into various extreme environments, the extreme natural conditions, such as extremely cold, wet, dirty, acidic and alkaline, etc, would have great damages on the devices, so their protection becomes necessary. Here the ZnO@stearic acid (ZnO@STA) superhydrophobic nanocone array surface is designed and grown by using a simple hydrothermal method on the Zn substrate and subsequent modification of each nanocone from head to toe with stearic acid, and the water contact angle attains 162°, and sliding angle is only 2°. Due to the strong binding force between the nanocone array and the Zn substrate, as well as the special modified array structure with self-reparability, its surface has superior mechanical stability and chemical stability, such as low surface energy, superlow adhesion, perfect abrasion resistance, good water shock resistance, ideal durability and well thermal stability in the working environment temperature range below 200 °C for the ZnO-based device, and so on. Meantime, it also exhibits remarkable omnipotent protection abilities: the high self-cleaning ability in the environments containing various solid and liquid pollutants, the well anti-corrosion performance in the acidic and basic environments, and the excellent freezing resistance in the harsh freezing conditions. The further tests illustrate the superlow adhesion and tiny contact area of liquid droplet caused by the superhydrophobicity and the unique nanocone array surface structure are the main reasons for these remarkable omnipotent protection abilities in the various extreme environments and superior mechanical stability.