Construction of robust superhydrophobic surfaces with electrothermal, photothermal properties using simple spraying method

Abstract

In this study, robust superhydrophobic surfaces with electrothermal, photothermal properties were fabricated by simple spraying method. In more detail, multiwall carbon nanotube (MWCNT) and silica were deliberately sprayed onto the wet poly(amide imide) (PAI) surface to construct intensive conductive network with hierarchical porous structure. The composite coating showed superhydrophobic with a water contact angle (CA) of greater than 155o and sliding angle (SA) of lower than 5o, conductivity of approaching to 1 kΩ sq-1. As expected, the composite coating possessed passive anti-icing property owing to its high CA, and the freezing time at -20 °C was obviously delayed from 150 to 600 s. On the other hand, the surface temperature respectively increased by 40 °C and 35 °C under the assistance of electric (voltage of 36 V) or light (0.23 W cm-2 irradiation) power, and the active anti-icing function can still work even under a such low temperature of -15 °C. It is worth noting that the heat generated by Joule effect was fixed on the conductive surfaces, and thus the composite coating showed good thermal insulation due to the low thermal conductivity of PAI substrate (0.298 W/mK) and hierarchical porous structure of composite coating. In addition, the surfaces showed high mechanical robust and durability, and the superhydrophobic and conductive properties were nearly unaffected even they suffered from lots of tests such as sandpaper abrasion, ultrasonic treatment, strong acid or strong alkali immerse, UV irradiation, and hot water jet impacting. Therefore, this study offered a simple way to fabricate electrothermal and photothermal surfaces for practical anti-icing/de-icing applications.