Effect of nano‐silica on gas permeation properties of polyether‐based polyurethane membrane in the presence of esterified canola oil diol as a nucleation agent for hard segments

In this research esterified canola oil diol (COD) was used to synthesize a green thermoplastic polyurethane. The mixture of synthesized COD as a polyester and polytetramethylene‐glycol as a polyether with different molar ratios were used to synthesize a thermoplastic polyurethane. Membranes were prepared by solution casting technique and nano‐silica particles were used to improve their gas separation performance. The effects of COD segments on phase separation and thermal properties of blocky segments of polyurethanes were evaluated using Fourier transform infrared spectroscopy and thermal gravimetric analysis. Results showed that phase separation behavior of the synthesized polyurethane was significantly increased with COD content. The COD segments showed high tendency to interact with hard segments of polyurethane in a way that new domains with higher thermal stability is created. Permeability of pure CO2, CH4, N2, and He gases were taken using constant pressure method at different pressures. Nano‐silica particles showed high inclination to interact with COD segments and significantly influenced the phase separation as well as gas permeation properties of polyurethane. Interactions of nano‐silica particles with the soft segments of polyurethane increased the glassy behavior of polymer and improved the CO2/CH4, CO2/N2, and CO2/He ideal selectivities (permselectivities).