No abstract

In recent years, microwave absorbing (MA) materials have developed rapidly and made good progress. However, MA materials with thin thickness and light weight are still a huge challenge. Furthermore, the application of single-function MA materials is severely restricted due to poor environmental adaptability in actual use, especially in harsh marine environments. Herein, we prepared graphene oxide/chiral polypyrrole hybrid (GO/CPPy) materials, which showed microwave absorbing properties combined with anticorrosion performance, by in situ polymerization. The sheet-layer GO/CPPy was composed of chiral helical polypyrrole and two-dimensional GO sheets. The introduction of chiral polypyrrole not only brought good dielectric loss but also produced additional magnetic loss. As a result, the GO/CPPy hybrids indicated a strong reflection loss (RL) of −55.5 dB at 8.55 GHz with a thickness of 3.8 mm. Meanwhile, they exhibited a broad effective bandwidth of 8.4 GHz from 9.1 to 17.5 GHz. In addition, 0.6% GO/CPPy-EP composite coatings displayed excellent long-term corrosion resistance with a remarkable corrosion protection capability (99.73%) after 21 days of immersion in a corrosive medium. Furthermore, the corresponding 6% GO/CPPy-EP microwave absorbing coatings retained high MA performance with a minimum RL of −27.5 dB at 12.38 GHz, which was tested using a bow reflectivity test system after immersion in 3.5% NaCl solution for 21 days. Moreover, the MA performance dropped only by 13.79%. This work could open new avenues toward the development of MA materials with corrosion protection performance.

Detecting and repairing coating damages at nanoscale or microscale are essential for metal corrosion protection. Here, we develop a smart anticorrosion coating with autonomous self-reporting and self-healing abilities by saline-responsive triggered polyaniline (PANi) nanocapsules containing a fluorescein isothiocyanate (FITC) fluorescent indicator and benzotriazidazole (BTA) corrosion inhibitor. Once the damaged coating is wet with the salt solution, the sodium ions penetrate the crack and react with PANi, causing a gating effect of PANi nanocapsules to be triggered and opened. This leads to the diffusion of molecules and expelling of the guest payload from the capsule mesopores. Therefore, the scratched FITC@PANi/Epoxy coatings express pronounced green fluorescence signals under UV light irradiation within only 30 min, highlighting the coating failure. Meanwhile, the microcracks can be promptly repaired with the BTA@ PANi/Epoxy coatings, and their long-term anticorrosion properties are further extended under a NaCl solution, indicating the prolonged service lives of the coatings. Therefore, the salt-responsive release strategy with self-reporting and self-healing functions allows for timely corrosion warning, fast crack repair, and effective extension of barrier performance, which is appealing and of great importance in practical applications.