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Proton exchange membrane (PEM) is a vital part of polymer electrolyte fuel cells (PEFCs). So it is of great importance to design the novel polymers for PEMs to improve the performance of PEFCs. Here two highly branched sulfonated copolymers (SBP-Cz-x) were synthesized based on a novel AB 2 monomer. For all we know, it is the first time that the 9H site of carbazole was used to prepare branched polymers. These copolymers given tough and transparent membranes by solvent casting method. SBP-Cz-x membranes exhibited excellent thermal stability and remarkable dimensional stability. Moreover, proton conductivity of SBP-Cz-x was very excellent. SBP-Cz-15 (IEC = 1.33 meq.g−1) owned high proton conductivity of 42.1 mS cm−1 at 80 °C. SBP-Cz-15 showed a pretty low swelling ratio of 12.7% with high water uptake (32.0%). SBP-Cz-x also owned remarkable oxidation stability. This study demonstrated that the strategy of fixing locally dense sulfonic acid groups on the branched points, which were surrounded by hydrophobic segment, could improve oxidative stability and dimensional stability efficiently. Image 1 • A novel carbazole derivative with six electron-rich phenyl was synthesized. • The 9H site of carbazole was used to synthesize sulfonated branch polymers. • SBP-Cz-x membranes owned remarkable dimensional stability and oxidative stability. [ABSTRACT FROM AUTHOR]

ABSTRACT A new bisphenol monomer containing a pair of electron-rich tetra-arylmethane units was designed and synthesized. Based on this monomer, along with commercial 4,4′-(hexafluoroisopropylidene)diphenol A and 4,4′-difluorobenzophenone, a series of novel poly(arylene ether ketone)s containing octasulfonated segments of varying molar percentage (x) (6F-SPAEK-x) were successfully synthesized by polycondensation reactions, followed by sulfonation. Tough, flexible, and transparent membranes, exhibiting excellent thermal stabilities and mechanical properties were obtained by casting. 6F-SPAEK-x samples exhibited appropriate water uptake and swelling ratios at moderate ion exchange capacities (IECs) and excellent proton conductivities. The highest proton conductivity (215 mS cm−1) is observed for hydrated 6F-SPAEK-15 (IEC = 1.68 meq g−1) at 100 °C, which is more than 1.5 times that of Nafion 117. Furthermore, the 6F-SPAEK-10 membrane exhibited comparable proton conductivity (102 mS cm−1) to that of Nafion 117 at 80 °C, with a relatively low IEC value (1.26 meq g−1). Even under 30% relative humidity, the 6F-SPAEK-20 membrane (2.06 meq g−1) showed adequate conductivity (2.1 mS cm−1) compared with Nafion 117 (3.4 mS cm−1). The excellent comprehensive properties of these membranes are attributed to well-defined nanophase-separated structures promoted by strong polarity differences between highly ionized and fluorinated hydrophobic segments. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 25-37 [ABSTRACT FROM AUTHOR]

A series of phenylsulfonic acid–containing poly(arylene ether ketone) (psa-PAEK) were synthesized via polycondensation from 2-(4-methoxy)phenylhydroquinone and other commercial monomers, followed by postsulfonation approach under mild reaction conditions. Controlled substituted sites and the degree of sulfonation were realized using quantities of 2-(4-methoxy)phenylhydroquinone. Giving the psa-PAEK can be soluble in common organic solvents such as Dimethylsulfoxide, purity ≥99.5% (DMSO, Sinopharm Chemical Reagent Co., Ltd, Shanghai, China), NMP, 1-Methyl-2-pyrrolidinone purity ≥99.0% (NMP, Sinopharm Chemical Reagent Co., Lted, Shanghai, China), and N,N-dimethylacetamide, purity ≥99.0% (DMAc, Sinopharm Chemical Reagent Co., Lted, Shanghai, China). The tough and transparent polymer membrane was prepared by the solution casting method, which exhibited excellent mechanical properties and high proton conductivities. The tensile stress at maximum load and elongation at break of these membranes are 28.3–34.1 MPa and 101–126% in dry state, respectively. The proton conductivities of these membranes were higher than 10−2 S cm−1 at room temperature in water. Especially, the psa-PAEK-90 with ion exchange capacity of 1.62 mequiv. g−1 exhibited the proton conductivity of 176 mS cm−1 at 80°C in water. The clear microphase separation morphology was observed by small-angle X-ray scattering, which is a powerful evidence to explain their high conductive behaviors. These results suggest that the psa-PAEK membranes have great potential as a candidate membrane for proton exchange membrane fuel cell applications. [ABSTRACT FROM AUTHOR]

A series of novel poly(arylene ether ketone)s with hexasulfophenyl pendents ( 6F-PAEK-SPx ) were synthesized by polycondensation reaction of commercial 4,4′-(hexafluoroisopropylidene)diphenol (6FBPA), 4,4′-difluorobenzophenone and a new difluoride monomer, and followed by a post sulfonation modification with chlorosulfonic acid. Controlling of substituent positions and the degree of sulfonation were realized using quantities of the new difluoride monomer. The structure of 6F-PAEK-SPx was confirmed by 1 H NMR and FT-IR instrument. The tough, flexible and transparent films of 6F-PAEK-SPx were obtained by solution casting. Those membranes with desired IEC values showed excellent thermal stability and mechanical properties. The membranes of 6F-PAEK-SPx copolymers containing hydrophobic main chain and hydrophilic micro-clustered pendent exhibited high proton conductivity and lower dimensional change value. The proton conductivity of 6F-PAEK-SP22 with the IEC of 1.77 meq/g was higher than that of Nafion 117 from 20 °C to 100 °C. The excellent properties of the membranes were attributed to the good hydrophobic/hydrophilic morphology of the membranes. The novel 6F‐PAEK‐SP copolymers combining the advantages of the well defined proton transport channels and enhanced physical properties will be the potential alternative materials to Nafion for PEMFC. [ABSTRACT FROM AUTHOR]

Abstract: New difluoride monomer containing a biphenyl pendant group is designed and synthesized for preparing side chain style polyelectrolyte. As a result, a novel poly(arylene ether)s containing flexible disulfonic acid pendant are obtained by a two-step synthetic procedure. First, poly(arylene ether)s with electron-rich side groups as polymer precursor (P-x) are prepared from designed difluoride monomer, 4,4′-difluorobenzophenone (DFDPK), and 4,4′-(hexafluoroisopropylidene)diphenol (6FBPA) by nucleophilic polycondensation. Then objective sulfonated polymers (I-x) are obtained from P-x and chlorosulfonic acid by sulfonation reaction. Tough, flexible, and transparent membranes having high mechanical strength are obtained by solution casting of I-x polymer. The membrane I-x exhibits high proton conductivity and good dimensional stability, which attributes their special side chain style structure. For example, I-50 membrane (IEC = 1.32 meq. g−1) shows low swelling of 8.1% and comparable conductivity with Nafion 117 at 80 °C. Suitable morphology is observed in I-x membranes by SAXS test, which may explain that I-x possess perfect overall properties. [Copyright &y& Elsevier]

Abstract: A novel sulfonated monomer sodium-3-(4-(2,6-difluorobenzoyl)phenoxy)propane-1-sulfonate was designed and synthesized. Based on above monomer, a series of sulfonated poly(arylene ether) copolymers containing aliphatic acid groups between aromatic backbones and sulfonic acid groups (PSOA-SPAE) were successfully prepared by direct copolymerization. Ion exchange capacity (IEC) of the copolymers could be mediated in the range of 1.07–1.61meqg−1 by the monomer ratios used in the copolymerization. These copolymers exhibited good oxidative and dimensional stability. The proton conductivities of copolymer films increased with the increase of IEC and temperature. The conductivity of PSOA-SPAE-80 was 4.94×10−2 Scm−1 at room temperature, and was up to 1.35×10−1 Scm−1 at 100°C, which was close to that of Nafion 117. These copolymers may be promising proton exchange membranes (PEMs) due to their high proton conductivity and good oxidative and dimensional stability. [Copyright &y& Elsevier]

Abstract: Side-chain-type sulfonated poly(arylene ether)s bearing sulfoalkyl pendant groups (PSA-SPAEs) as proton exchange membranes for fuel cells were prepared via nucleophilic substitution polycondensation reactions of sodium 3-(4-(2,6-difluorobenzoyl)phenyl)propane-1-sulfonate (SDFPPS), 4,4′-dihydroxyldiphenylether (DHDPE) and 4,4′-dichlorodiphenyl sulfone (DCDPS). The sulfonic acid group content (SC), as the quantity per repeat unit of polymer, ranging from 0.5 to 0.8, was readily controlled by changing the feed ratio of SDFPPS to DCDPS. Good thermal properties of PSA-SPAE copolymers were indicated by observing glass transition temperatures (T gs) ranging from 210 to 230°C in sodium salt form and decomposition temperatures (T ds) over 220°C in acid-form and over 400°C in sodium-form in air. All PSA-SPAE membranes exhibited reasonable flexibility and tensile strength in the range of 41–78MPa. PSA-SPAE copolymers bearing sulfonic acid groups on flexible side chains showed considerably reduced swelling ratio and improved proton conductivities. Proton conductivity curves parallel to those of Nafion 117 were obtained with proton conductivity of 10−1 S/cm at equivalent ion exchange capacities (IEC) of 1.47 and 1.64, comparable to Nafion 117. PSA-SPAE copolymer with SC 0.8 had the best data including PEM mechanical strength, water swelling and proton conductivity. [Copyright &y& Elsevier]

The development of high-performance and low-cost membrane materials is crucial for proton exchange membrane fuel cells. To improve the proton conductivity, we designed a novel multiple phenyls monomer. Then, we synthesize a series of sulfonated poly(aryl ether sulfone ketone) membranes (SPAESK- x). The hydrophilic groups are densely distributed in units after sulfonation, which can form large hydrophilic ion clusters and provide more connected channels for proton transport. The large hydrophilic ion clusters facilitate the separation of hydrophilic and hydrophobic phases to form wider proton transport channels. The SPAESK-15 membrane achieves a high proton conductivity (181.0 mS cm-1) at 80 °C. The novel monomer and polymers are budget and simple to synthesize, offering the possibility of large-scale preparation. Overall, the novel structure has the potential to develop high-performance electrolyte materials. [Display omitted] • A novel monomer and a series of PEMs (SPAESK- x) are designed. • Densely sulfonated structural facilitates microphase separation of SPAESK- x. • Large hydrophilic ionic clusters promote the connectivity of hydrophilic channels. • The proton conductivity of SPAESK-15 membrane is 180 mS cm-1 at 80 °C. • The power density of SPAESK-15 membrane can achieve 370 mW cm-2 at 80 °C. [ABSTRACT FROM AUTHOR]

Abstract: Branched sulfonated poly(aryl ether ketone) copolymers (Br-SPAEKs) were synthesized based on 4,4′-(hexafluoroisopropylidene) diphenol (6F-BPA, A2 monomer), 4,4′-difluorobenzophenone (DFBP, unsulfonated B2 monomer), 3,3′-disodiumsulfonyl-4,4′-difluorobenzophenone (SDFBP, sulfonated B2 monomer) and 2,4′,6-trifluoro-benzophenone (TFBP, branched BB′2 monomer). Structures of Br-SPAEKs were confirmed by FT-IR and NMR. Compared to linear sulfonated poly(aryl ether ketone) copolymer (L-SPAEK) membrane with similar ion exchange capacity (IEC), these Br-SPAEK membranes showed a higher proton conductivity and a lower methanol permeability. This synergistic effect on proton conductivity and methanol permeability was mainly due to the characteristics of large free volume and similar to cross-linking architecture arising from the introduction of the branched monomers. Moreover, the Br-SPAEK membrane containing 20mol% branched monomer possesses the best selectivity, and the value of selectivity is almost 3 times higher than that of L-SPAEK. Proton conductivities of Br-SPAEK membranes are higher than 10−2 S/cm and increase gradually with increasing temperature. At 80°C, the proton conductivity of Br-20-SPAEK-40 (branched monomer of 20mol% and sulfonated monomer of 40mol%) membrane reaches 0.121Scm−1, compare to that of Nafion 117 (0.139Scm−1). Additionally, the methanol permeability of Br-20-SPAEK-40 is one order magnitude lower than that of Nafion 117. [Copyright &y& Elsevier]

Abstract: A series of novel organic–inorganic hybrid proton exchange membranes were prepared from sulfonated poly(arylene ether sulfone) (Am-SPAES) with 4-amino-phenyl pendant group, (3-isocyanatopropyl)triethoxysilane (ICPTES) and tetraethoxysilane (TEOS) using a sol–gel method. The reactive ICPTES was used to react with the amino pendant groups of Am-SPAES to form covalent bonds between Am-SPAES and SiO2, which could effectively improve the compatibility between the polymer matrix and the inorganic SiO2 phase. The obtained hybrid membranes exhibited excellent thermal and oxidative stability. The mechanical properties of the membranes were enhanced and the swelling ratio of the membranes was reduced by introducing the cross-linking network structure. Especially, these hybrid membranes possessed higher water uptake and proton conductivities compared to the pristine Am-SPAES membrane when the SiO2 content was 3 and 6wt%, whereas the same properties of the obtained hybrid membranes decreased when the SiO2 content was 10wt%. All of the membranes showed much lower methanol permeability than Nafion 117 did. In addition, the dispersion of the inorganic particles (SiO2) in the Am-SPAES matrix could be improved by the strong covalent interactions between Am-SPAES and SiO2. [Copyright &y& Elsevier]

Abstract: A novel bisphenol monomer containing concentrated electron rich phenyls is synthesized, which provides a locally and densely postsulfonation sites. Based on this monomer, a series of new sulfonated poly (ether sulfone)s (SPESs) are successfully obtained by nucleophilic substitution reaction, followed by postsulfonation using concentrated sulfuric acid. All the polymer membranes are readily prepared by solvent casting and exhibit excellent thermal stability and mechanical properties. As ion exchange capacity (IEC) ranging from 0.98 to 1.66 mequiv g−1, the polymers afford considerable proton conductivity and water absorption. SPES-3 with IEC = 1.66 mequiv g−1 shows equal proton conductivity (0.131 S cm−1) to Nafion 117 at 100 °C under fully hydrated state. At low IEC level (IEC = 0.92 mequiv g−1), SPES-1 also exhibits higher conductivity (>10−2 S cm−1) than some earlier reported sulfonated random polymers. Their excellent performance is attributed to the internal structure of the polymers, which formed distinct phase separation between hydrophilic and hydrophobic moiety observed by SAXS. A combination of high proton conductivities, moderate water uptake, suitable mechanical properties and low swelling ratios for some of the obtained SPES indicates that they are good candidate materials for proton exchange membranes (PEMs). [Copyright &y& Elsevier]

The advancement of proton conductive applications will require the identification of new membrane with high-conductivity and good dimensional stability that can be readily obtained and cheap. We reported a novel rigid carbazole derivative and proton exchange membrane consisting of densely sulfonated carbazole derivative, which could form aggregated ionic cluster of sulfonic acid group and result in continuous broad-dimensional nanochannels. The SAXS analysis confirmed these copolymers owned large ion clusters. All of membranes prepared in this work were thermally stable at up to 250 oC. These membranes also exhibited excellent dimensional stability and outstanding proton conductivity. SPESK-Cz-15 with IEC = 2.07 meq g-1 showed the largest water uptake with a value of 107%, but the swelling ratio was only 36.4% at 100 oC, which was attributed to the artful structure of the copolymers. SPESK-Cz-15 showed very high proton conductivity (165.3 mS cm-1 at 80 oC), which was 1.53 times higher than that of Nafion 117 (108 mS cm-1 at 80 oC). Besides, the maximum power density of SPESK-Cz-15 was 1642.7 mV cm-2 at 80 oC under 95% RH. The stability of single cell based on SPESK-Cz-15 was remarkable. All above indicate that SPESK-Cz-x are potential materials for polymer electrolyte membrane fuel cells in the future. Image 1 • A novel carbazole unit with octa-sulfonated sites was synthesized. • SPESK-Cz-x owned excellent thermal stability and phrase separation. • SPESK-Cz-x showed remarkable proton conductivity and fuel cell performance. [ABSTRACT FROM AUTHOR]