Poly(ether sulfone)s using a rigid dibenzothiophene dioxide heterocycle

Abstract

Poly(aryl ether)s were prepared by nucleophilic aromatic substitution using conformationally restricted dichloro‐ and difluorodibenzothiophene dioxide heterocyclic monomers with bisphenol A or bisphenol AF. The heterocyclic monomers were prepared from the bis(4‐halophenyl) sulfones in two steps via lithiation followed by copper catalyzed intramolecular coupling and characterized by ^1H, ^(13)C, ^(19)F NMR spectroscopy and GC/MS. Reactivity of the fluorine containing monomer was examined using semi‐empirical methods and NMR spectroscopy measurements and found to be potentially more reactive than bis(4‐fluorophenyl) sulfone, even with a conformationally locked sulfone as the electron withdrawing group. Successful polymerizations of both the fluorine and chlorine containing monomers with bisphenol A and bisphenol AF nucleophiles were accomplished, providing polymers with number average molecular weights of approximately 45 kg/mol (difluoro monomer) and 10–20 kg/mol (dichloro monomer). The polymers exhibited high T_gs ranging from 238 to 256 °C and displayed good thermal stability with 5% degradation temperatures in air from 453–510 °C, depending on molecular weight and bisphenol composition.

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