Development of anti-corrosion coating with sandwich-like microvascular network for realization of self-healing and self-reporting properties based on coaxial electrospinning

Biomimetic microvascular networks prepared by coaxial electrospinning technology have attracted much attention as a novel form of carrier for encapsulating active substances. However, the poor interfacial bonding strength between traditional electrospinning materials and metal substrates limits its application in anti-corrosion coatings. Herein, a novel poly(vinyl alcohol) grafted phytic acid (PVA-PA) electrospinning solution was synthesized. And a sandwich-like microvascular network (SMN) was prepared by coaxial electrospinning technology, which used PVA-PA solution as the shell material, epoxy resin 51 (E51), tetraphenylethylene (TPE) and polyamide resin as the core materials, respectively. Owing to the high porosity of SMN, epoxy resin can be directly spin-coated on it to form a composite coating (PVA-PA/SMN/EP). It is proved that due to the strong chelation and coordination interaction between PA and mild steel, the pull-out adhesion of the PVA-PA/SMN/EP composite coatings on mild steel was increased by 0.92 MPa. In addition, by systematically optimizing the relative viscosity, miscibility, conductivity, and saturated vapor pressure between the two jets of the core solution and the shell solution in coaxial electrospinning, the microvascular structure of the coaxial electrospinning nanofibers was improved and the fluidity of the internal active substances was maintained. When the PVA-PA/SMN/EP composite coating generates microcracks, the active substances encapsulated in the SMN flow out, in which the three-dimensional crosslinked network formed by the curing of E51 and polyamide resin enhances the spatial interactions between TPE molecules, which results in TPE emitting a bright blue fluorescence. This work provides a new approach for the development of the next generation of smart anti-corrosion coatings.