Synthesis of sPEEK

SULFONATED POLY(ETHER ETHER KETONE) 143 Sulfonated poty(ether ether ketone) (PEEK) 

For DS 30%, sPEEK polymers are soluble in dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or A-methylpyrrolidone (NMP). For DS 50%, sPEEKs are soluble in A,iV-dimethylacetamide (DMAc) also at room temperature [151], while for DS above 60%, sPEEKs are highly swollen in methanol/water solution at 80-90 °C, and for these reasons, they are not suitable for DMFC applications [155]. For DS 70%, sPEEKs are soluble in methanol, and for DS = 100%, in hot water [182,183]. When PEEK sulfonation is carried out via the concentrated sulfuric acid procedure, it is limited and takes place only on the four chemically equivalent positions of the hydroquinone segment and the DS does not exceed the value of 100% owing to the electron-withdrawing deactivating 

TABLE 3.4 sPEEK Polymer Solubility at Various DS aud Different Solvents 

13 Aromatic proton nomenclature for a generic sPEEK repeat unit. 

TABLE 3.5 Ion Exchange Capacity and Snlfonation Degree of Pristine sPEEK Polymers Literature Data 

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