Intrinsic Self-healing Material With Improved Strength And Toughness Tailored For Smart Anticorrosion Coating Applications

In this paper,an intrinsic room temperature self-healing elastomer was first synthesized via implanting a large number of supramolecular hydrogen bonds into polyuria matrix.Subsequently,for the shortcomings of low mechanical strength,low-cost and widely used g-C₃N₄ nanosheets were incorporated into self-healing polymer to prepare the intrinsic self-healing composite?PUU-g-C₃N₄ NS?.Based on these,the as-prepared PUU-g-C₃N₄ NS composite were employed to construct intrinsic self-healing anti-corrosion coating.Overall,this research paper can be divided into three parts.Firstly,the g-C₃N₄ nanosheets?g-C₃N₄ NSs?were prepared by a liquid exfoliation route from bulk g-C₃N₄,which synthesized by the the calcinationofmelamineathightemperature.Afterthat,the toluene-2,4-diisocyanate-terminated polypropylene glycol,adipic acid hihydrazide,and the as-prepared g-C₃N₄ NSs were used to prepare room temperature self-healing PUU-g-C₃N₄NSs that simultaneously possess high strength and toughness.The structure,morphology,thermastability,mechanical strength and self-healing capability were characterized by Fourier Transform Infrared Spectrometer?FT-IR?,Scanning Electron Microscope?SEM?,Thermogravimetric Analysis?TG?,Differential Scanning Calorimetry?DSC?,Dynamic Thermomechanical Analyzer?DMA?,Tensile Tester and Fluorescence microscope.The results demonstrat that g-C₃N₄ NSs are uniformly dispersed into self-healing composite matrix,and the Young's modulus,tensile strength of PUU-g-C₃N₄ NS are significantly increased by the increase of g-C₃N₄ NSs.There are a large number of hydrogen bonds in self-healing PUU-g-C₃N₄ NS composite matrix.Meanwhile,the T_g values of them are much lower than room temperature.Thus,the PUU-g-C₃N₄ NS composite exhibit excellent intrinsic self-healing capability at room temperature.Typically,when the content of g-C₃N₄ NS is up to1.0wt%,the healing efficiency of PUU-g-C₃N₄ NS?24 h at room temperature?is as high as86.4%.Finally,the prepared self-healing PUU-g-C₃N₄ NS was dissolved in DMF,and then dropped onto the surface of aluminum alloy to construct intrinsic self-healing anti-corrosion coating?PUU-g-C₃N₄ NSs AC?.Tear test,hardness test,pull-out adhesion test and impact resistance test confirm that the mechanical properties of PUU-g-C₃N₄ NSs AC fully meet the application requirements of the anti-corrosion coating.Electrochemical impedance spectroscopy test?EIS?,Tafel test showed that PUU-g-C₃N₄ NSs AC possess excellent corrosion resistance,and the coating did not be corroded after immersion in 0.5 M NaCl for20 days.Laser microscopy and Kelvin probe?SKP?test confirmed PUU-g-C₃N₄ NSs AC shows self-healing function.When the coating is damaged,the corrosion resistance of the coating can self-recover within 10 min.