Novel Sulfonated Co-poly(ether imide)s Containing Trifluoromethyl, Fluorenyl and Hydroxyl Groups for Enhanced Proton Exchange Membrane Properties: Application in Microbial Fuel Cell

Abstract

A hydroxyl group containing new cardo diamine monomer was synthesized, namely 9,9-bis (hydroxy- (4'-amino(3-trifluoromethyl)biphenyl-4-oxy)-phenyl)-9H-fluorene (mixture of isomers, HAPHPF). HAPHPF, along with a sulfonated diamine monomer, 4,4'-diaminostilbene-2,2'-disulfonic acid (DSDSA), was used to prepare a series of new sulfonated copolyimides by polycondensation with 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA). The degree of sulfonation (DS < 1) was adjusted by the feed ratio of DSDSA/HAPHPF and the copolymers were named as DHN-XX, where XX denotes the mole percentage of DSDSA (XX = 50, 60, and 70). The copolymers showed high molecular weights. The copolymer structure and composition were confirmed by FTIR and NMR techniques. Copolymer membranes were prepared through solution cast route by using dimethyl sulfoxide as a solvent. The membranes showed high thermal, mechanical, hydrolytic and peroxide radical stability, and low water uptake and low swelling ratios. Well-separated hydrophilic and hydrophobic phase morphology was observed in TEM and AFM images of the copolymer membranes and was further supported by the SAXS studies. The proton conductivity of the DHN-70 was as high as 97 mS cm at 80 °C and the value is significantly higher than that of the nonhydroxylated analogue. The membranes also showed superior microbial fuel cell (MFC) performance, similar like Nafion 117 under similar test conditions. The chemical oxygen demand removal values provide substantial evidence that the fabricated membranes can be utilized in bioelectrochemical systems.

Synthesis and Characterization of New Phosphorus Containing Sulfonated Polytriazoles for Proton Exchange Membrane Application

“…The SAXS patterns specified that the maxima of ionic scattering moved to a higher q value with increase in DS of the sulfonated membranes. This supports to the findings from the AFM images; a development in ionomeric domains (dark areas) with the gradual increase in DS value and the orderly shrinkage of hydrophobic domains (bright areas) . The upsurge in DS values is a consequence of the increase size of the ionic clusters or the decrease in their distance which pushed the scattering maxima to higher q .…”

“…(b)]. However, none of the sulfonated polymers showed any kind of thermal transition within 50–300 °C in the DSC curve and this was ascribed to the strong ionic interactions among the rigid triphenylphosphine oxide and sulfonic acid (─SO 3 H) groups with the triazole rings …”

“…As a general process, the sulfonic acid group (─SO 3 H) was connected to the polymer backbone to the analogous ionomers in PEMs . Sulfonated polybenzimidazoles, sulfonated poly(arylene thio ether)s, sulfonated poly(arylene ether)s, sulfonated poly(arylene ether sulfone)s, sulfonated polyimides, sulfonated polytriazoles, and their offshoots have been scrutinized extensively as PEM materials.…”

Sulfonated co‐poly(ether imide)s with alkyne groups: Fabrication of crosslinked membranes and studies on PEM properties including MFC performance

“…In our earlier studies, [31,32] we observed that the incorporation of trifluromethyl, fluorenyl and phenolic OH groups in S-coPIs resulted in PEM with superior set of physical properties. While the trifluromethyl and fluorenyl groups helped in getting well-defined phaseseparated morphology, the OH groups helped enhance the peroxide resistance of the PEMs.…”

Preparation of sulfonated polysulfone/sulfonated titanium dioxide hybrid membranes for DMFC applications

“…Aromatic hydrocarbon polymers such as polyimides (PIs), poly(ether ether ketone)s (PEEKs), and poly(arylene ether sulfone)s (PAESs) show high inherent stability, high glass transition, and low cost, as a result they are attractive alternatives which are expected to replace Nafion. Usually, these polymers are sulfonated by chlorosulfonic acid, fuming sulfuric or other strong sulfonating agent.…”