Synthesis and characterization of fluorinated polyimide/TiO₂ nanocomposites: enhancement of separation of four gases, thermal, optical and mechanical properties

Nanocomposite gas transport and thermally stable membrane-based fluorinated polyimide/TiO₂ nanoparticles were prepared via in situ sol–gel fabrication. PI/TiO₂ nanocomposites containing 4, 8, and 12% TiO₂ were successfully fabricated by in situ sol–gel fabrication. The obtained PI/TiO₂ nanocomposites were characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry analysis, X-ray powder diffraction, field emission-scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM). Thermogravimetric analysis data indicated an increased thermal stability of the PI/TiO₂ nanocomposites compared to the pure polymer. The results of gas permeation showed the permeability of ethylene and propylene increased in PI/TiO₂ nanocomposites compared to the pure PI. The diffusion coefficients of prepared hybrid membranes were determined by the time lag method. The results showed an increase in the solubility coefficient and a decrease in the diffusion coefficient of gases while increasing the TiO₂ nanoparticle mass fraction.