Multi-type nanoparticles in superhydrophobic PU-based coatings towards self-cleaning, self-healing and mechanochemical durability

Abstract

Mechanochemical durability is a key limited factor for superhydrophobic coatings to produce the real applications in some important fields. Herein, the superhydrophobic PU-based coatings were firstly synthesized with silica particles (F-SiO2) and carbon nanotube (F-CNT) as the main fillers and the reinforced mediums, respectively. The superhydrophobic coatings showed excellent water repellency with higher water contact angle of 154.3° and lower sliding angle of only 5°. Also, the impacting droplets could rapidly bounced off the superhydrophobic coatings with the contact time of 11 ms. The superhydrophobic coatings exhibited the excellent self-cleaning property. Furthermore, the as-prepared superhydrophobic coatings (F-CNT to F-SiO2 mass ratio was 3:3) possessed the robust mechanochemical durability with higher bonding strength to the aluminum substrates, and the coatings could retain their high superhydrophobicity after over 100 cycles of sand abrasion under a load condition of 1.1 kPa. In strongly acidic and alkaline solutions for 6 h, the composite coatings were intact and showed high ability to resist the chemical erosion. Even though the superhydrophobic coatings suffered the UV damage, the water repellency could be restored under thermal treatment at 135 °C for 3 h. All these excellent performances were attributed to the rational regulation of nanoparticles in superhydrophobic PU-based composite coatings.