Novel spirobisindane-containing thermally rearranged (TR) benzoxazole(spiroTR-PBO) membraneswere prepared by thermal treatment of four newly synthesized spirobisindane-containing hydroxylpolyimides (spiroHPIs). Transport properties of spirobisindane-containing polymers were investigatedalong with fractional free volume and density measurements, as well as molecular simulation analysis.The resulting spiroTR-PBOs exhibited high free volumes and superior mechanical properties in terms ofelongation and tensile strength, and these findings were supported by molecular dynamic simulations.SpiroTR-PBO membranes containing hexafluoroisopropylidene moiety in the polymer backboneshowed a six-fold increase in CO2permeability, compared to that of the spiroHPI precursor. SpiroTRPBO membranes showed strong potential to be applied in carbon capture and separation of gases
because of their high gas permeability coupled with robust mechanical properties
