Fabrication of a robust superhydrophobic coating from the aqueous self-assembly of perfluoropolyether-based triblock copolymers

Abstract

Five types of poly(hydroxyethyl methacrylate)m-perfluoropolyether-poly(hydroxyethyl methacrylate)m triblock copolymers (HFHm) with different poly(hydroxyethyl methacrylate) chain lengths were synthesized successfully. The as-synthesized HFHm can self-assemble into micelles in water with perfluoropolyether core surrounded by poly(hydroxyethyl methacrylate) corona under a dilute concentration. By casting the mixture of the HFHm micelles in water, hydrophilic silica nanoparticles and hydrophilic polyisocyanates as a cross-linking agent, a robust superhydrophobic surface can be obtained on smooth substrates. The addition of silica nanoparticles and polyisocyanates enhances the surface roughness and mechanical durability of the coatings. Due to the high surface roughness (Ra = 889 nm) and the high surface fluorine content (41.9 wt%), the cross-linked HFHm superhydrophobic coating can reach a water contact angle of 157.8 ± 0.7° and a water sliding angle of 3.5 ± 0.6°. After 30 abrasion cycles or immersion for 22 h in strong acid (pH 2) and weak alkaline (pH 9) solutions, the coating still maintains its superhydrophobicity. These phenomena indicate that the HFHm can be used as a kind of environment-friendly coatings with superhydrophobicity.