Effect of Graphene Carbon Nitride on Ultraviolet-Curing Coatings

Graphene carbon nitride (g-C3N4) was successfully prepared by semi-closed pyrolysis and then incorporated into the ultraviolet (UV)-curing system to synthesize different specimens of g-C₃N₄-hybridized UV-curing (g-C₃N₄/UV) coatings. The apparent appearance and dispersity g-C₃N₄ were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The influence of the curing speed and mechanical properties was also tested. The dispersion level of g-C₃N₄ can be kept less than 1 μm by mechanical mixing. The pencil hardness of composite coatings could be 6H while the adhesion based on glass could be 1 level. The degree of curing of the coating could be obviously improved by the addition of g-C₃N₄, leading to a 7 percent increase of the gel content. Additionally, the decomposition of hard segments of polyurethane acrylate could be avoided by the use of g-C₃N₄ resulting in an increasing stability to heat. We found the gel content in an aerobic environment was lower than that in an anaerobic environment. On this basis, the function and mechanism of g-C₃N₄ was investigated in detail and methods to eliminate the O₂ were proposed.