Mechanically robust thermally rearranged (TR) polymer membranes with spirobisindane for gas separation

Novel spirobisindane-containing thermally rearranged (TR) benzoxazole(spiroTR-PBO) membranes were prepared by thermal treatment of four newly synthesized spirobisindane-containing hydroxylpolyimides (spiroHPIs). Transport properties of spirobisindane-containing polymers were investigated along 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 of elongation and tensile strength, and these findings were supported by molecular dynamic simulations. SpiroTR-PBO membranes containing hexafluoroisopropylidene moiety in the polymer backbone showed a six-fold increase in CO2 permeability, compared to that of the spiroHPI precursor. SpiroTR-PBO 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. (C) 2013 Elsevier B.V. All rights reserved.