Synthesis of sulfonate ester and sulfonic acid-containing poly(arylene perfluorocyclobutane)s (PFCB) by direct copolymerization of a sulfonate ester-containing precursor

This paper reports the first synthesis of sulfonated poly(arylene perfluorocyclobutane)s by direct polycondensation of a new sulfonate ester-containing bis(trifluorovinylether) precursor and subsequent hydrolysis of the resulting polymers. The multi-step synthesis of a bis(trifluorovinylether) monomer bearing sulfonic acid groups protected as sulfonate esters (SE-TFVE) is described. Based on this precursor and 4,4′-bis(trifluorovinyloxy)biphenyl (4,4′-TFVE), sulfonate ester-containing poly(arylene perfluorocyclobutane) copolymers (SE-PFCB) were synthesized by 2π + 2π step-growth cyclopolymerization. Their thermal and physico-chemical properties were characterized. Free acid polymers (SA-PFCB) were subsequently obtained by hydrolysis of sulfonate ester groups. A preliminary evaluation of the proton conductive properties of these polymers is reported.