Investigating CO[formula omitted], O[formula omitted] and N[formula omitted] permeation properties of two new types of nanocomposite membranes: Polyurethane/silica and polyesterurethane/silica

Abstract

The current study presents a synthesis method of two new types of polyurethane-based nanocomposite membranes: polyurethane/silica and polyesterurethane/silica. The main difference between the membranes is the type of the polyol used in the synthesis of their polymers. The polymers were synthesized via two-step polymerization and then the polymeric membranes were prepared by solution casting-solvent evaporation. To prepare the nanocomposite membranes, silica nanoparticles were loaded into polyurethane matrices with different contents (5, 10, and 15 wt. %). In order to evaluate the chemical bond variations, glass transitions, crystalline structure and morphology of the membranes, the prepared membranes were characterized using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and scanning electron microscopy (SEM), respectively. Permeation properties of pure gases CO2, O2 and N2 through all the membranes were measured using a constant pressure method at different pressures (6, 8, and 10 bar) and temperatures (25, 35, and 45 °C). Acquired results of permeation experiments show that increasing of silica nanoparticles loading in matrices of both membrane types, decreases gases permeability values but increases ideal CO2/N2 and O2/N2 selectivity values. The results also revealed that the PU400-based nanocomposite membranes have higher performance for CO2/N2 separation, while the PU100-based nanocomposite membranes exhibit higher performance for O2/N2 separation.