Immiscible blends of sulfonated polyetheretherketone and fluorinated polyimide for proton exchange membranes

Abstract

Both multitrifluoromethylated polyimide (12F-PI) and sulfophenylated polyetheretherketone (Ph-SPEEK) were synthesized in order to build immiscible blends for proton exchange membranes (PEMs). The 12F-PI/Ph-SPEEK blend membranes had improved dimensional stability and oxidation stability in comparison with pure Ph-SPEEK. Despite the introduction of the hydrophobic 12F-PI content, the proton conductivity of blends 1 and 2 showed significantly increased proton conductivity at 80–100°C. The interesting phase-separation morphology, in which the “inorganic-like” particles formed by 12F-PI dispersed in Ph-SPEEK, was observed. This morphology similar to inorganic–organic blends could be highly related to the big differences in the hydrophobicity/hydrophilicity and backbones of two polymers. The obtained results suggest that this series of blend membranes may be potential PEMs for fuel cells.