Highly-transparent fluorinated epoxy coating prepared via ring-opening of thiolactone and thiol-click reactions for robust omniphobicity

Abstract

Transparent omniphobic coatings have attracted extensive research over the past decade to meet growing application demands. Polydimethylsiloxane (PDMS)-based anti-fouling coatings have been widely reported to contribute a liquid-like surface for liquid repellency. The bulky PDMS chains usually make the surface greasy and energy-consuming. Fluorinated epoxy is expected to overcome the above drawbacks and contribute to excellent mechanical robustness. However, the reported fluorinated epoxy coatings are unsatisfactory due to severe phase separation, excessive fluorine content, poor self-healing and weatherability. In this work, a thiolactone-terminated fluorinated prepolymer (TTFP) was prepared through thiol-click chemistry. The thiolactone structure limited the phase separation and reacted efficiently with epoxy resin in a thiol-click manner after ring-opening. The flexible TTFP molecules had a strong surface migration ability, allowing the product coating to be liquid repellent with a low fluorine content and self-healed after damage. Therefore, a low-cost, eco-friendly, anti-ultraviolet, self-healed, highly transparent, mechanically robust and chemically resistant fluorinated epoxy coating was proposed. In addition to the excellent repellency to ink traces, fingerprints and thick paint, the coating with 5H pencil hardness could maintain omniphobic properties after 100 h of intensive UV irradiation or 12 h of alkali corrosion. Benefiting from the strong surface migration ability of flexible fluoroalkyl chains, the coating could recover its omniphobicity within 30 min of heating. The characterization results show the excellent comprehensive properties of the coating and its great potential for application in various scenarios.