Sulfonated nanocrystal cellulose/sulfophenylated poly(ether ether ketone ketone) composites for proton exchange membranes

Nanocomposites were prepared with sulfonated nanocrystal cellulose (sNCC) and sulfophenylated poly(ether ether ketone ketone) (Ph-SPEEKK) for studying proton exchange membranes. The properties, including proton conductivity, mechanical properties, water uptake and swelling ratio were thoroughly investigated. The proton conductivity of the sNCC/Ph-SPEEKK composite membrane was much higher than that of pure Ph-SPEEKK in the range of 30–90 °C when the sNCC ratio was less than 10%. The presence of the hydroxyl and sulfonic acid groups on the sNCC was supposed to benefit the network formation via hydrogen bonds for the proton conduction. In addition, the mechanical properties of the composite membranes were much improved compared with those of the pure Ph-SPEEKK membrane. And the swelling ratio of the composite membranes was acceptable for the application. It was proved that the incorporation of sNCC into the sulfonated polymer matrix as a component to enhance the performance of the proton exchange membrane is one of the promising preparation strategies.