Comparative study of the anti-corrosive properties of thiols induced superhydrophobic surfaces

Fluoroalkyl thiols and alkyl thiols are widely used as low surface energy reagents for the preparation of superhydrophobic surfaces and corrosion resistant surfaces. Although the corrosion resistance of thiol-induced superhydrophobic surfaces has been well addressed previously, few studies have devoted to revealing the difference of fluoroalkyl thiol and alkyl thiol modified surfaces towards anti-corrosion. In this work, two types of superhydrophobic surfaces were prepared by respectively coating self-assembled monolayers (SAMs) of 1 H,1 H,2 H,2 H-perfluorodecanethiol (PFDT) and 1-dodecanethiol (DDT) on femtosecond laser engineered copper substrates. The formation mechanism of the SAMs was explained by analyzing the surface chemical composition. The water contact angle of the PFDT and DDT modified surfaces were measured to be 157.7° and 154.6°, respectively. Electrochemical tests showed that both SAMs significantly reduced the corrosion current density (Icorr) and corrosion rate of the copper surfaces, while simultaneously increased the charge transfer resistance (Rct) value by an order of magnitude compared to the pristine copper surface. The surface with PFDT SAM had the smallest Icorr and its Rct value was about 1.5 times larger than that with the DDT SAM. These results confirmed that both the SAMs enhanced the anti-corrosion properties of the copper surfaces, and the PFDT SAM was proved to be more effective. Furthermore, the anti-corrosion durability of the PFDT and DDT modified surfaces were compared after exposing them to salt, acid, and alkali solutions for 12 h, and the results showed that the surfaces maintained to be hydrophobic and anti-corrosive, and the PFDT induced superhydrophobic surface indicated better durability. Our results demonstrated that thiols SAMs could significantly improve the anti-corrosion property of structured metal surfaces, and that fluoroalkyl thiol was more desired for long-term anti-corrosive applications in comparison with alkyl thiol. [Display omitted] •Superhydrophobic surfaces were prepared by laser ablation and thiols self-assembly.•As-prepared superhydrophobic surfaces exhibited excellent corrosion resistance.•Anti-corrosive properties of self-assembled fluoroalkyl and alkyl thiols were compared.•Fluoroalkyl thiol induced surfaces are more desired for long-term anti-corrosion.