RETRACTION: Synthesis and characterization of a novel sulfonated poly (aryl ether ketone sulfone) containing rigid fluorene group for DMFCs applications (Retraction of Vol 299, Pg 93, 2020)

A new sulfonated poly (aryl ether ketone sulfone) consisting of rigid fluorene groups (SPAEKS) is synthesized from 3, 3 '-disulfonate-4, 4 '-dichlorodiphenylsulfone, and 9, 9-bis (4-hydroxyphenyl) fluorene by a typical condensation polymerization. The chemical structure of SPAEKS is characterized by H-1-NMR and FTIR spectra. SPAEKS-x membranes have moderate water absorption, swelling rate, good oxidative stability, and excellent thermal stability. The proton conductivity of SPAEKS-x membranes is in the range of 38.5-66.5 mS/cm. In particular, the proton conductivity of SPAEKS-50 membrane is 66.5 mS/cm, which is slightly higher than Nafion117 membrane (63.5 mS/cm) measured under the same conditions. All membranes show much lower methanol permeability and much higher proton selectivity than Nafion 117 membrane. Especially, proton selectivity of SPAEKS-40 membrane (13.8 x 10(4) S s cm(-3)) is about 4 times higher than that of Nafion 117 membrane (3.6 x 10(4) S s cm(-3)).