Fabrication of robust, durable and integrated Janus coating for corrosion and fouling protection in marine environment

Janus membranes with different valuable characteristics and integrated structures have attracted a great interest of researches in order to achieve important breakthroughs in the related fields. However, the application of Janus membranes for development of anticorrosion coatings on metallic structures has been limited, which is due to weak interfacial bonding within the Janus structure and its vulnerability to damage. To address the aforementioned drawbacks, a novel strategy based on multifunction Janus membranes is presented. In this research, the steel is coated with polyurethane, followed by electrospinning a coating composed of polyurethane nanofibers with kaolin nanoparticles, and finally coated with epoxy resin containing modified ZnO to obtain the Janus membrane. The interface of the Janus membrane is accompanied by covalent bonds, leading to 10-fold enhancement in interface adhesion compared to the resin coating. The obtained Janus coating has a top surface that is superhydrophobic and a bottom surface that is hydrophilic, with excellent antiwetting and antibacterial properties. Moreover, the Janus coating shows outstanding barrier properties and the corresponding impedance modulus is maintained about 109 omega center dot cm2 after 75 immersion days. Notably, the coating surface has retained superhydrophobicity after abrasion test with 600-grit sandpaper under a load of 1000 g for 60 m distance. The antibacterial tests have shown the Janus coating could decrease the bacterial coverage on the surface by 25 %. This study has revealed the potential of the Janus electrofibrous membrane as directly coatings on the metallic substrates for the first time, and in this way, multifunction coating with corrosion and fouling protection performances has been achieved.