Construction of Double-Shell Hollow TiO2 toward Solvent-Free Polyurethane Films

Solvent-free polyurethane (SFPU) has a fast curing film-forming speed, making the foam and coating layer very dense. Therefore, this film structure has poor hygienic properties. Here, we propose a strategy for introducing double-shell hollow TiO2 microspheres (S@S-TiO2) having a large specific surface area and a special inner and outer cavity structure in the SFPU film, so that the film would develop excellent hygienic properties. First, novel S@S-TiO2 were successfully prepared by a one-step hydrothermal method, which is very rare. Then, the obtained S@S-TiO2 were introduced into SFPU to prepare an S@S-TiO2/SFPU composite film. Then, the morphology and dispersibility of S@S-TiO2 and the composite film were studied by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The results show that S@S-TiO2 have an important effect on the hygienic properties of the composite film. Finally, the synergistic effect of TiO2 on the properties of the polyurethane film was further proved by molecular dynamics simulation.