High-adhesive superhydrophobic litchi-like coatings fabricated by in-situ growth of nano-silica on polyethersulfone surface

This work presents the preparation of durable superhydrophobic polyethersulfone (PES) composite coating with large water contact angle of 157.2 ± 1.3° and small sliding angle of 3 ± 0.5°. The interface bonding force between PES and SiO 2 nanoparticles was enhanced through the dopamine self-polymerization on the surfaces of PES particles during the sol-gel process. After surface modification with 1 H ,1 H ,2 H ,2 H -perfluorooctyltriethoxysilane (POTS), superhydrophobic PES-PDA-SiO 2 -POTS coating was easily prepared by a simple one-step spraying method with less than 2.6 wt% SiO 2 . The dosage of nanoparticles to establish micro/nano structures for superhydrophobic coating was much less than the previously reported, which is beneficial to improve the interface bonding force between PES and SiO 2 . The prepared coating can still remain superhydrophobicity even after 84 h of immersion in a 3.5 wt% NaCl solution. The durable superhydrophobicity was mainly attributed to the litchi-like structure that trapped more air to effectively prevent water infiltration. Combined with the high interface bonding force of PES-SiO 2 and the low concentration of SiO 2 , the adhesive ability of the coatings accorded with Grade 0 of GB/T9286, which represented the best adhesive strength. In addition, the wear life of the PES-PDA-SiO 2 -POTS coating was prolonged to 8 times than that of PES/SiO 2 /POTS coating. Potentiodynamic polarization plots indicated that the coating had great corrosion resistance , low corrosion current density of 9 × 10 −9  A/cm 2 and high corrosion protection effect of 99.99%. The superhydrophobic PES-PDA-SiO 2 -POTS coating can be also highly applied on different substrates. It is believed the PES-PDA-SiO 2 -POTS coating may have great potential for large-scale applications.