A comparative structure–property study of methylphenylated and fluoromethylphenylated poly(aryl ethers) and their gas permeabilities and permselectivities

Two novel poly(aryl ether)s, dimethylphenylated poly(ether nitrile) (6H-PEN) and dimethylphenylated poly(ether ether ketone) (6H-PEEK), derived from (3,5-dimethylphenyl)hydroquinone monomer, were synthesized via aromatic nucleophilic substitution polycondensation. They showed high glass transition temperatures and were soluble in common solvents. A comparison of gas permeabilities and permselectivities among methylphenylated (3H-PEEK and 3H-PEN), trifluoromethylphenylated (3F-PEEK and 3F-PEN), dimethylphenylated (6H-PEEK and 6H-PEN) and 3,5-ditrifluoromethylphenylated (6F-PEEK and 6F-PEN) poly(aryl ether)s were studied. Compared with the methylated polymers, the corresponding fluoromethylated polymers had generally higher permeabilities. The 3F and 6F polymers had combined permeabilities and permselectivity properties attractive for O2/N2 separation. 6F-PEN exhibited the best gas separation properties for the O2/N2 pair, and P(O2), and P(O2)/P(N2) values were 6.6 and 5.9, respectively.