In recent years, metal corrosion causes serious threats to the economy of the world and the living environment. Hence, it is very important to seek non-toxic and environmentally friendly materials with metal anti-corrosion properties for the sustainable development of society. The barrier properties of graphene oxide (GO) and the special electrochemical property of polyaniline (PANI) can significantly improve the corrosion resistance of metals. Herein, we developed an in-situ polymerization method to prepare graphene oxide/polyaniline (GO/PANI) nanocomposites with unique anti-corrosion properties. The obtained GO/PANI nanocomposites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermalgravimetric analysis, UV–vis spectroscopy and scanning electron microscopy. The as-prepared composite materials were uniformly dispersed in epoxy resin to prepare anticorrosive coatings and coated on the surface of steel. The anti-corrosion performance of the coatings was measured by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization technique. The EIS results showed that the total impedance of epoxy/GO/PANI coatings is greater than epoxy/PANII coatings, and the impedance module value can reach 8.67 × 108 Ω·cm2. In general, it is concluded that the anti-corrosion performance of GO/PANI coating is significantly higher than PANI coating and pure GO coating.

At present, high-sensitivity, high-penetration-depth, and accurate tissue resolution clinical imaging effect are required, while computer transverse scanning, microwave imaging, and fluorescence imaging (FL) cannot meet the requirements of clinical imaging, but the magnetic resonance imaging (MRI) can meet the requirements of clinical dissecting details. The effect of MRI imaging is closely related to the contrast agent (CA). As an important type of CA, Fe3O4 and its analogues have been widely concerned because of their low toxicity and relatively low price. In this review, we summarize the development and improvement of CAs based on Fe3O4 and its analogues from T 2 imaging mode and development limitation in the initial single modulus imaging mode, to T 1 imaging mode overcoming the limitations of T 2 imaging and the limitations of its own in application, to the later development of dual modulus imaging form, and to the current multi-modulus imaging form. Simultaneously, we demonstrate the research progress, preparation methods, and future trends based on Fe3O4 and its analogues CAs for MRI, the current application status is preliminarily summarized, and the future development trend is prospected.

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