Robust superhydrophobic coating with carbon nanotubes and silica nanoparticles in the matrix of fluorinated polyurethane

After years of research, superhydrophobic coatings have made great progress, but the complex preparation process and poor durability are still key issues that limit their practical application. Herein, we developed a room temperature cured durable superhydrophobic coating through a simple spraying method. The main polymer matrix used in this study was fluorinated polyurethane (FPU), which exhibited high hardness (5H), strong adhesion to the substrate (grade 1, GB/T 9286), and excellent hydrophobicity with a contact angle of approx. 108 ° Silica nanoparticles were found to be highly effective in enhancing the surface hydrophobicity of FPU. Nevertheless, these particles can be easily removed from the surface by even a simple touch with a finger. For enhanced durability, we incorporated carbon nanotubes (CNTs) with intertwining structures. Additionally, polydimethylsiloxane (PDMS) was utilized to facilitate the interaction between the inorganic fillers and the organic FPU matrix, owing to its inorganic Si-O skeleton and organic side chains. The so-optimised composite coating was covered with micro-/nano- particles and the hydrophobicity was enhanced greatly (contact angle of ∼165 ° and sliding angle of 5.5 °). The contact angle of the coating remained higher than 150 ° even after undergoing a range of tests. These tests included immersing in corrosive solutions for 60 h, gravel impacting for 100 cycles, water jetting for 1200 s, and abrading against sandpaper for 1000 cycles. The good chemical and mechanical durability was due to the high compactness, high hardness (4H pencil hardness), and high adherence (grade 1, GB/T 9286) of the coating. Moreover, due to the photothermal conversion effect of carbon nanotubes, the coating possessed excellent photothermal performance and showed good application prospects in anti icing / deicing.