Sulfonated poly(ether imide)s with fluorenyl and trifluoromethyl groups: Application in microbial fuel cell (MFC)

• Fluorenyl moiety containing sulfonated co-polymers were synthesized.
• The co-polymers showed high peroxide radical resistance and hydrolytic stability.
• Nano-phase separated morphology for all the co-polymers were observed.
• The copolymers showed proton conductivity up to 149 mS cm−1.
• The copolymers showed good microbial fuel cell performance.

A series of fluorenyl and trifluoromethyl groups containing co-poly(ether imide)s (S-co-PIs) have been prepared from a new diamine monomer; 9,9-bis(3-methoxy-4-(4-amino(3-trifluoro-methyl)biphenoxy)phenyl)-9H-fluorene (APHPF). The polymers were prepared by the polycondensation reaction of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) with two different diamines; APHPF and 4,4′-diaminostilbene-2,2′-disulfonicacid (DSDSA) as a co-monomer. The monomer and polymers were well characterized by 1H NMR and ATR-FTIR spectroscopies. The co-polymers were soluble in various organic solvents and membranes were prepared from solution cast route. The S-co-PIs showed high thermal and mechanical stability. TEM and AFM results supports the formation of phase separated morphology with well separated ionic-clusters. All these S-co-PIs displayed reasonably high proton conductivity. One of the copolymers (DAN-80; IECw ∼2.27 meq g−1) exhibited a proton conductivity as high as 149 mS cm−1 which was comparable to that of Nafion® 117 (165 mS cm−1) at 80 °C. The co-polymers maintain a good balance between water-uptake and swelling ratios and peroxide resistance. Microbial Fuel Cell (MFC) performance of the co-polymers were evaluated DAN-80 exhibited a similar performance like Nafion® 117 under similar test condition.

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