Synthesis and properties of highly branched star-shaped sulfonated block poly(arylene ether)s as proton exchange membranes

Star-shaped sulfonated block copoly(ether ketone)s exhibit excellent properties for use as proton exchange membranes (PEMs). However, very few investigations of the use of highly branched star-shaped sulfonated block polymers as PEMs have been reported. In this work, two types of highly branched star-shaped sulfonated block poly(arylene ether)s with 6% branching agent were synthesized via direct polycondensation reactions of a trifunctional core (branching agent) with sulfonated 4,4′-difluorobenzophenone, bisphenol fluorene, and 4,4′-difluorodiphenyl sulfone. The properties of a polymer with hydrophilic segments surrounded by hydrophobic segments (P1) and a polymer with hydrophobic segments surrounded by hydrophilic segments (P2) were investigated. The block polymer P1 exhibited better oxidative stability (332min) and dimensional stability (