Three novel fluorinated polymers with ether-bond-free aryl backbones were obtained by one-pot, metal-free, room temperature superacid catalyzed non-stoichiometric step polymerization of 1,1,1-trifluoromethyl acetone with carbazole (CBZ), fluorene (FLN) and 9,9-dimethylfluorene (DFL). ¹H and ¹³C NMR analyses of the polymers revealed their linear structure and high regioselectivity of the polymer forming reaction. The polymers also possess high thermostability with decomposition temperature up to 387 °C for CBZ and up to 530 °C for FLN and DFL as well as reasonable mechanical properties. The gas transport properties of six pure gases and binary gas mixture CO₂/CH₄ (10/90 mol%) are reported. These polymers present a good combination of permeability and selectivity up to 10 bar at 35 °C for CO₂/CH₄ mixed-gas feed. DFL exhibits the best pure-gas permeability and selectivity (PCO2 = 78.0, P_H2 = 151.5, CO₂/CH₄ = 22.3 and H₂/CH₄ = 43.3) and mixed-gas permeability and selectivity CO₂/CH₄ (P_CO2 = 71.3, CO₂/CH₄ = 23.7) at 35 °C and 2 bar with a slight decrease in selectivity at 10 bar. The highest permselectivity is obtained for FLN (CO₂/CH₄ = 36.7 and H₂/CH₄ = 88.4) with a separation performance close to the 2008 upper bound trade off.