Construction And Corrosion Resistance Of Superhydrophobic Surface Based On Metals

Inspired by the biological adhesion protein of mussels,dopamine can be solidly selfpolymerized in a mild alkali environment on any substrate,including polymer,glass metal etc.In this paper,the metal(brass and 316 L Stainless steel)samples were first polished by water abrasive paper,followed by spontaneous polymerization of dopamine to generate PDA film.The PDA was subsequently functionalized with 1H,1H,2H,2H-perfluorodecanethiol to yield a perfluorinated coating(fPDA).A superhydrophobic coating successfully constructed on the metal substrate showed highly corrosion resistance.The results of water contract angle show that the fluorinated polydopamine modified metal specimens with appropriate roughness can have a contact angle of more than 150°,showing superhydrophobic properties.X-ray photoelectron spectroscopy(XPS),attenuated total reflection Fourier transform(FTIR-ATR)spectroscopy,scanning electron microscopy(SEM)and energy dispersive X-ray spectroscopy(EDS)revealed the formation of uniform,compact and superhydrophobic coating through in-situ polymerization interactions and chemical grafting on brass.The reaction process of superhydrophobic film formation on the metal surface is as follows: the DA coating firstly adhered to the brass substrate by the chelation of catechol with metal surface.Then,self-polymerization of DA occurred in the alkaline solution to enable the formation of a layer of solid PDA coating.Finally,PFDT,as a low surface energy material,was grafted onto the PDA film on the brass substrates of different roughness by means of Michael addition.The results of traditional electrochemical tests and advanced micro-electrochemical technique indicated that Cu-coated with fPDA possessed a lowest corrosion current density,and a highest coating resistance,showing better corrosion resistance in 3wt.% NaCl solution.In addition,the degree of hydrophobicity of the surface can affect the polarization resistance of the surface.The stronger the hydrophobicity,the greater the polarization resistance and the better the corrosion resistance.The main reason for the corrosion resistance of this superhydrophobic fPDA coating is that the microstructure of the coating appear as ‘‘hillsvalleys’ ’,which can easily trap air among the ‘‘valleys’ ’.In addition,the micro-nano structure can reduce the capillarity.A feasible and environmentally friendly approach was developed for the fabrication of super-hydrophobic and anti-corrosion coating on brass and316 L stainless steel.According to the surface characterization and analysis,it was found that the fluorinated polydopamine coating is chemically bonded to the metal surface and has a strong interfacial bonding force.Due to the special structure of the surface,this coating exhibited high corrosion resistance in a 3wt.% NaCl solution,and as its degree of hydrophobicity increases,its corrosion resistance will be stronger.This study provides an effective and cost-efficient way for material protection and may give inspiration in the fields related to surface and interface engineering,such as materials,biology and medicine.