A polymer of formula (I):

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where: n is an integer from 10 to 5,000; m is an integer from 10 to 5,000; Ar1 and Ar3 are the same or different and are residues derived from a tetra-hydroxy aromatic monomer, the tetra-hydroxy aromatic monomer being

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wherein R is the same or different and is H or a C₁-C₈alkyl, C₂-C₈alkenyl or C₃-C₈cycloalkyl group; and, Ar2 and Ar4 are the same or different and are residues derived from a tetra-halogenated aromatic monomer, the tetra-halogenated aromatic monomer being

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wherein X is F, Cl or Br, and R1 and R2 are the same or different and are

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wherein y is an integer from 1 to 8; with the proviso that when Ar1 is the same as Ar3 and Ar2 is the same as Ar4, R1 and R2 are not both â€”CN is useful as a material for gas separation, vapor separation, adsorbents or catalysis.