New sulfonated poly(arylene ether sulfone) copolymers containing phenyl side chains as proton exchange membranes
A new series of sulfonated poly(arylene ether sulfone) copolymers containing phenyl side groups with different sulfonation degrees (SPAES PQ xx) were successfully synthesized through direct aromatic nucleophilic substitution polycondensation of 3,3' disulfonate 4,4' dichlorodiphenylsulfone, 4,4 dichlorodiphenylsulfone and phenylhydroquinone (PQ) The degree of sulfonation was realized by controlling the quantity of the sulfonated monomer. The chemical and phase separated structures of copolymers were characterized by proton nuclear magnetic resonance spectroscopy and atomic force microscopy. The properties of flexible and transparent SPAES membranes were evaluated. Compared to the hydroquinone based SPAES membrane (SPAES HQ 40) the effect of the phenyl side group on the water absorption properties, swelling properties and proton conductivity of SPAES PQ xx membranes was explored. The results demonstrated that the introduction of phenyl side groups could result in better dimensional, thermal and oxidative stability compared with those of the SPAES HQ 40 membrane. In addition, the proton conductivity of SPAES PQ 40 is up to 0.096 S cm 1 at 80 degC.