Preparation of UV-curable functionalized phosphazene-containing nanotube/polyurethane acrylate nanocomposite coatings with enhanced thermal and mechanical properties

Poly(cyclotriphosphazene-co-4,4′-sulfonyldiphenol) (PZS) nanotubes with active hydroxyl groups were fabricated via an in situ template method under mild conditions, and then modified by acryloyl chloride to obtain the acryloyl-group functionalized PZS (f-PZS) nanotubes. The structure of the PZS nanotubes was characterized by Fourier transform infrared spectroscopy and the morphology was investigated by scanning electron microscopy and transmission electron microscopy. The f-PZS/polyurethane acrylate (f-PZS/PUA) nanocomposite coatings were prepared by UV radiation technology to covalently introduce f-PZS nanotubes into a PUA matrix. Dynamic mechanical analysis and tensile tests were performed to characterize the mechanical properties of the f-PZS/PUA nanocomposite coatings. The optimal reinforcing effect for the PUA matrix was observed when the content of f-PZS nanotubes was 3.0 wt%. The thermal stability of the PUA nanocomposites was studied by thermo gravimetric analysis. It indicates that the onset thermal degradation temperature of the f-PZS/PUA nanocomposites with 1.0 wt% f-PZS nanotubes is increased by 36.3 °C. These remarkable property reinforcements are attributed to the covalent functionalization of PZS nanotubes, which can effectively improve the interfacial interaction between the f-PZS nanotubes and the PUA matrix.