Sulfonated copoly(phthalazinone ether ketone nitrile)s as proton exchange membrane materials

Abstract

Sulfonated poly(phthalazinone ether ketone nitrile) copolymers (SPPEKN) were prepared by copolymerization of disodium 3,3′ -disulfonate-4,4′ -difluorobenzophenone (SDFB-Na), 2,6-difluorobenzonitrile (2,6-DFBN), and 4-(4-hydroxyphenyl)-1(2H)-phthalazinone (DHPZ) at 160• C in N-methyl-2-pyrrolidione containing anhydrous potassium carbonate. The polymerization reactions proceeded smoothly and in high yield giving high molecular weight SPPEKN copolymers with different sulfonic acid content (SC) values. The polymer structures were defined by 1 H NMR and FT-IR. Membrane films of SPPEKN copolymers in both salt and acid forms, prepared at SDFB-Na to 2,6-DFBN feed ratios up to 60/40 mol/mol, were cast from the N,N-dimethylacetamide (DMAc) polymer solutions. The presence of highly polar nitrile groups are expected to increase interchain molecular forces, contributing to the observed reduction in water swelling over previously prepared sulfonated poly(phthalazinone ether ketone) (SPPEK) copolymers. Membranes containing nitrile groups are expected to show improved adhesion between polymer and catalyst when utilized in a fuel cell. All SPPEKN copolymers exhibited tensile strength higher than that of Nafion ® 117. The proton conductivities of acid form SPPEKN copolymers (SPPEKNH)s, prepared at the sulfonated/unsulfonated monomer feed ratio above 0.35 mol/mol, were around 10 −1 S/cm at 80• C, which is close to or higher than that of Nafion ® 117 under same measurement conditions.

Comparative effect of phthalazinone units in sulfonated poly(arylene ether ether ketone ketone) copolymers as proton exchange membrane materials

“…2 Among recently developed polymer electrolyte membranes, sulfonated poly(arylene ether sulfone) (SPAES) and sulfonated poly(arylene ether ketone) (SPAEK) are promising. [3][4][5][6][7][8][9] Wang et al 9 reported the synthesis of biphenyl-based SPAES.…”

“…It was reported that the low water swelling obtained was due to hydrogen bonding involving the carbonyl groups of the oxyphenyl phthalazinone unit. In our previous article, 5 we described the synthesis of poly(phthalazinone ether ketone nitrile)s. The 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one (DHPZ) monomer can readily undergo a nucleophilic substitution reaction to give polymer because the phthalazinone NH groups behave like phenolic OH groups. Therefore, the phthalazinone monomer is used for preparing high-performance engineering plastics.…”

Sulfonated poly(fluorenyl ether ketone nitrile) electrolyte membrane with high proton conductivity and low water uptake

“…−1 with the increasing sulfonation degree from 0.8 to 1.8. Although with such low EW, the water uptake at 35 • C are limited from 14.8% to 66.7% for membranes a-e and 444.4% for copolymer f. Membranes a-e have much lower water uptake when compared with the polymers that did not contain nitrile at similar EW [16][17][18][19]. A plausible factor for this is the presence of strong nitrile dipole interchain interactions that combine to limit swelling water [28].…”

“…More recently, it has been reported that the introduction of nitrile groups into sulfonated poly(aryl ether sulfone) and poly(aryl ether ketone)s can reduce their water uptake and dimensional swelling [16][17][18][19]. In addition, the introduction of strongly polar nitrile groups most probably promotes the adhesion of polymers to other components via interaction with other polar chemical groups.…”

Synthesis and characterization of sulfonated poly(arylene ether sulfone) ionomers incorporating perfluorohexylene units for DMFC membranes

“…4 Meanwhile, owing to the high thermal stability, excellent mechanical strength, and strong resistance to membrane decomposition in an acidic water medium, sulfonated poly (arylene ether sulfone) ionomers (SPAES) have been considered a promising alternative to the Nafion ® . [5][6][7][8][9] However, when SPAES membranes have high degree of sulfonation, in particular, above 50%, they tend to deliver relatively high methanol permeability and water uptake, which results in the low selectivity (a ratio of proton conductivity to methanol permeability) and the poor cell performance. One of the possible approaches to overcome these drawbacks is to introduce fluorinated groups into the SPAES.…”