To produce proton exchange membranes (PEMs) with robust
mechanical
properties, poly(fluorenyl terphenyl piperidinium) (PFTP) with an
aromatic backbone is synthesized. Sulfonated PFTP (SPFTP-x) is obtained by introducing propanesulfonic acid onto PFTP as a
side chain to enhance its phosphoric acid (PA) adsorption capacity
and proton conductivity. Both the PFTP and SPFTP-x membranes exhibit good thermal, oxidization, and dimensional stabilities
owing to their rigid ether-free aromatic backbones. Because of the
introduction of propanesulfonic acid side chains, the SPFTP-x membranes show higher PA adsorption capacity and higher
proton conductivity than the PFTP membrane. The PA doping content
of the SPFTP-x membranes is more than 160% at room
temperature, and their conductivity can be up to 109.0 mS cm–1 at 160 °C under anhydrous condition. Furthermore, a single
cell assembled with SPFTP-50 exhibits a maximum power density of 280
mW cm–2 at 100 °C. These results indicate that
SPFTP-x is a promising membrane material for applications
in high-temperature proton exchange membrane fuel cells.