Mixed Matrix Membranes Based on Fluoropolymers with m- and p-Terphenyl Fragments for Gas Separation Applications

Novel mixed matrix membranes (MMMs) based on fluoropolymers with m- and p-terphenyl fragments and NaX zeolites were prepared. The fluoropolymers were synthesized by a one-pot, room-temperature, metal-free superacid-catalyzed stoichiometric and nonstoichiometric step polymerization of 2,2,2-trifluoroacetophenone with two multiring aromatic nonactivated hydrocarbons (p-terphenyl and m-terphenyl). MMMs were characterized by scanning electron microscopy (SEM) and infrared (Fourier transform infrared (FTIR)) spectroscopy and used in gas permeability tests. SEM analysis showed interfacial voids in MMMs prepared in N-methyl-2-pyrrolidone (NMP), The interfacial adhesion in the polymer-zeolite system was considerably improved when chloroform was used as a solvent. Permeability coefficients for pristine polymer membranes were 1.3-fold higher in CHCl₃ than in NMP for p-terphenyl fragment and 2.0 times higher in NMP than in CHCl₃ for the polymer with m-terphenyl fragment. The incorporation of NaX zeolites in the polymeric matrices improved the gas permeability coefficients compared to the pristine membranes. The effects of polymer architecture, casting solvent, and interaction between the organic matrix and the inorganic particles on the gas separation performance of the developed MMMs were investigated.