Self-healing superhydrophobic coating with durability based on EP + PDMS/SiO2 double-layer structure design.

Superhydrophobic coatings often face challenges related to poor friction and corrosion resistance. In this study, composite coatings were developed, featuring a top layer of SiO 2 nanoparticles and a bottom layer of epoxy resin (EP) and polydimethylsiloxane (PDMS). As the number of SiO 2 nanoparticles layers increased, surface roughness escalated, and the coating structure transitioned from SiO 2 nanoparticles entirely encapsulated by EP and PDMS to a small fraction of SiO 2 exposed on the coating surface. Leveraging the rough surface and low-free-energy properties endowed by Si-(CH 3) 2 and Si-O-Si hydrophobic groups, coatings comprising 3–5 layers SiO 2 nanoparticles exhibited superhydrophobicity and self-cleaning capabilities. These coatings retained their superhydrophobic properties even after enduring heavy friction from sandpaper, and demonstrated robust corrosion resistance over extended periods. Increasing the number of SiO 2 layers not only enhanced superhydrophobicity, corrosion and friction resistance, but also improved the coating-substrate adhesion. The designed coating structure exhibited superior corrosion resistance and coating-substrate adhesion compared to those of EP/PDMS + SiO 2 double-layer and EP + PDMS + SiO 2 mixed coatings. Moreover, the coatings displayed a self-healing ability, regaining superhydrophobicity following O 2 or Ar etching, facilitated by the upward movement of hydrophobic groups/bonds and intensity recovery. Coatings subjected to Ar etching exhibited better self-healing properties due to higher Si-O-Si and lower C-C/C-H bond intensities. This research presents novel insights for the practical application of superhydrophobic coatings. • Coating structure with all or a part of SiO 2 surrounded by EP and PDMS was designed. • Rough surface with low surface energy led to coating superhydrophobic and self-clean. • Improving SiO 2 layers number achieved good adhesion, corrosion and friction durability. • Coatings present better corrosion durability and adhesion than other structure design. • Hydrophobic groups floating up and intensity recovery were coating self-heal reason. [ABSTRACT FROM AUTHOR]