Anti-icing polyimide thin film with microcolumns fabricated by RIE with cooling and PCVD

Anti-icing polyimide (PI) thin films are a promising anti-icing technology for aircraft. A processing method combining reactive ion etching with cooling and plasma chemical vapour deposition is proposed to fabricate anti-icing PI thin films with microcolumns (PI-M). The anti-icing performance of PI-M was examined. The apparent contact angle (APCA) was 153° ± 1.4°, and the APCA hysteresis was 8.5° ± 0.5°. The calculated Weber number was high, and a droplet on PI-M rebounded within 2.56 s, whereas rebounding occurred more slowly on a smooth PI surface (PI-S). The freezing time of droplets on PI-M was 70% longer than that on PI-S. The average ice adhesion force on PI-M was 42% smaller than that on PI-S. Repeated measurements of the ice adhesion force on PI-M demonstrated that it was stable (deviation: ±1 N). The APCA showed that PI-M is superhydrophobic, which indicates that droplets on PI-M were in the Cassie state. The droplet bouncing behaviour was explained in terms of horizontal force equilibrium at the interface. The anti-icing mechanism of PI-M was modelled using heterogeneous nucleation theory and a contact area model. The results explained the good anti-icing performance and suggested that PI-M may have excellent potential for anti-icing applications.