Gas transport properties of novel aromatic poly- and copolyamides bearing bulky functional groups

Abstract

The synthesis and properties of novel aromatic poly- and co-polyisopthalamides bearing –OH, -tert-butyl (TERT) and 3,5-bis(trifluoromethyl) benzoyl (BTFB) groups are reported. All synthesized aramides are highly soluble in aprotic solvents, thermally stable up to 400°C and present good film forming ability. The combination at random of -OH group with TERT or BTFB groups in copolymers CPA 1 and CPA 2 is highly effective for improving gas permeability (P) for all tested gases (CO2, O2, N2, CH4) and selectivity (α) for CO2/CH4 and CO2/N2. Copolymer CPA 2b containing OH and BTFB groups exhibited high gas permeability and good selectivity (PCO2=60.17 and PCH4=2.67, α=22.53) in comparison with analogous polyamides and some polyimides. These results are well correlated with both the increase in fractional free volume (FFV) and interchain d-spacing.