2-Chloromethylbenzimidazole loaded and polyethyleneimine/poly(sodium-p-styrenesulfonate) decorated fumed silica as filler to prepare pH stimuli-responsive and self-healing epoxy composite coating

In this paper, based on the loading of the corrosion inhibitor 2-chloromethylbenzimidazole (2-CBI) into polyporous fumed silica (FS) and following sequential deposition of poly(sodium-p-styrenesulfonate) (PSS) and polyethyleneimine (PEI) onto the surface of the loaded FS (PEI-PSS-2CBI-FS), a pH-stimulated filler was manufactured. Later, a composite coating (EP-PEI-PSS-2CBI-FS) was prepared by adding PEI-PSS-2CBI-FS into the epoxy resin. The results showed that when the scratched EP- PEI-PSS-2CBI-FS was immersed in a 3.5 wt% NaCl solution with pH = 2.0, it can continuously release 2-CBI. Compared to pure epoxy coating (EP) and epoxy coating with crude FS (EP-FS) as filler, the impedance value of scratched EP-PEI-PSS-2CBI-FS in a 3.5 wt% NaCl solution with pH = 2.0 gradually increased with immersion time, showing a clear self-healing behavior. Most importantly, the impedance value of the scratched EP-PEI-PSS-2CBI-FS gradually increased during immersion in a 3.5 wt% NaCl solution with a lower pH (0.5 and 2.0) rather than decreased when pH = 4.0 and pH = 7.0. The EP-PEI-PSS-2CBI-FS coating exhibits well-defined pH stimulus responsive ability. [Display omitted] •A pH stimuli-responsive nano-carrier (PEI-PSS-2CBI-FS) was prepared.•PEI-PSS-2CBI-FS can release 2-CBI quickly and continuously in an acid solution.•Epoxy resin/PEI (PEI-PSS-2CBI-FS) composite coating (EP-PEI-PSS-2CBI-FS) shows an obvious self-healing ability.•EP-PEI-PSS-2CBI-FS exhibits well-defined pH stimulus responsive ability.