ABSTRACTSulfonated poly(ether ketone ether sulfone) (S-PEKES) was successfully prepared to obtain the currently highest degree of sulfonation of 0.744. Sulfonated graphene oxide (S-GO) was incorporated into the S-PEKES matrix to increase sulfonic groups (SO3H) which significantly improved the proton conductivity, methanol blocking, and mechanical stability. The proton conductivity of the S-GO/S-PEKES composite membrane was enhanced up to 5.93 × 10?2 S.cm?1, which was 7 times higher than the commercial Nafion 117. S-GO exhibited additional positive effects namely the blocking of methanol passing through the membrane, leading to lower methanol crossover than Nafion 117 by two orders of magnitude and high mechanical stability. 相似文献
Methanol permeability is a major drawback for application of sulfonated polystyrene ethylene butylenes polystyrene block copolymers (SPSEBS) in direct methanol fuel cells (DMFC). Modification of SPSEBS by layer-by-layer (LBL) assembly of aminated (APSU) and sulfonated polysulfone (SPSU) was attempted to reduce its methanol permeability. The LBL deposition of APSU and SPSU on SBSEBS was carried out by dipping in their solutions alternatively for 10 min. The LBL assembly was confirmed by SEM analysis. The methanol permeability was lower than SPSEBS and Nafion 117. The proton conductivity, ion exchange capacity, and water absorption were lower than SBSEBS but higher than Nafion 117. Its selectivity ratio (0.70 × 105) was higher than both SBSEBS (0.54 × 105) and Nafion 117 (0.06 × 105). The maximum power density of LBL (62 mW/cm2) was about five times higher than SBSEBS. These features of LBL confirm the LBL assembly method as a very simple procedure to modify SBSEBS for application in DMFC. 相似文献
Partially sulfonated poly(vinylidene fluoride) (SPVdF) has been prepared by incorporation of sulfonic acid groups within poly(vinylidene fluoride), using chlorosulfonic acid as the sulfonating agent. The degree of sulfonation (DS) has been varied by modulating the duration of the sulfonation reaction. Blending of SPVdF (having DS = 36.78%) with Nafion at a constituent wt.% ratio of SPVdF:Nafion = 70:30 has resulted in the fabrication of polymer electrolyte membrane with superior properties compared to pristine Nafion‐117 membrane. This particular blend composition exhibited a proton conductivity value of 3.6 × 10−2 S cm−1 (i.e. ∼12.5% increase over Nafion‐117), a methanol permeability value of 6.81 × 10−7 cm2 s−1 at 6M methanol concentration (i.e. ∼99.31% decrease from Nafion‐117) and a corresponding membrane selectivity value of 5.29 × 104 Ss cm−3 (i.e. an increase of approximately two‐orders of magnitude over Nafion‐117) at 20 °C. In addition, this blend composition has also exhibited (a) better heat stability at temperatures as high as 160 °C by virtue of it possessing higher glass transition temperature, (b) higher storage modulus, (c) higher stress relaxation at high angular frequency and (d) superior DMFC performance at high methanol feed concentration in presence of humidified, as well as, non‐humidified air as the catholyte, compared to Nafion‐117 membrane. 相似文献
A series of phthalonitrile end-capped sulfonated polyarylene ether nitriles are synthesized via K2CO3 mediated nucleophilic aromatic substitution reaction at various molar ratios. The as-prepared polymer structures are confirmed by 1H NMR and FTIR spectroscopy. The properties of membranes cast from the corresponding polymers are investigated with respect to their structures. The membranes exhibit good thermal and mechanical properties, low methanol permeability (0.01?×?10?6–0.58?×?10?6 cm2·s?1 at 20 °C), and high proton conductivity (0.021–0.088 S·cm?1 at 20 °C). The introduction of phthalonitrile is proved to increase intermolecular interaction, mainly contributing to the reduction in water uptake, swelling ratio, and methanol permeability. More importantly, its introduction does not decrease the proton conductivity, but there is a slight increase. Furthermore, the selectivity of SPEN-CN-50 can reach 4.11?×?105 S·s·cm?3, which is about nine times higher than that of Nafion 117. All the data show that the as-prepared membranes may be potential proton exchange membrane for DMFCs applications. 相似文献
A series of novel hybrid sulfonated polynorbornene‐silica (PBN–SiO2) proton conducting membranes doped with different weight ratio of phosphotungstic acid (PWA) were prepared by the casting procedure. The proton conductivity of the composite membranes containing 40 wt.% PWA reached the maximum of 6.1 × 10–2 S cm–1 and increased gradually with PWA content and temperature elevating, while the methanol permeabilities (3.52–9.39 × 10–7 cm2 s–1) of these membranes were much lower than that of Nafion 117 (2.36 × 10–6 cm2 s–1). The membranes also exhibited excellent thermally stable and mechanical properties, which imply that the PBN–SiO2–PWA membranes are promising materials in the direct methanol fuel cells (DMFC) applications. 相似文献
In this work, semiinterpenetrating polymer network (semi-IPN), consisting of sulfonated poly (arylene ether sulfone) (SPAES) and crosslinked vinyl imidazole grafted polysulfone (VMPSU), is prepared and characterized. FTIR, EDS, and solubility test indicate the successful preparation of amphoteric membranes. The semi-IPN amphoteric membranes exhibit better stability than pure SPAES membrane, as demonstrated by thermogravimetric analysis and ex situ immersion testing results. More importantly, it is shown that the amphoteric membrane can effectively hinder vanadium ion crossover through the membrane, which is attributed to the semi-IPN structure and Donnan exclusion. As expected, the amphoteric membrane containing 20% VMPSU exhibits the highest proton selectivity (6.86 × 104 S min cm−3), comparing to pristine SPAES (1.90 × 104 S min cm−3) as well as Nafion117 (1.31 × 104 S min cm−3). 相似文献
Intent on developing efficient proton exchange membranes used for direct methanol fuel cells as well as hydrogen fuel cells, a series of membranes based on sulfonated polyetheretherketone and sulfonated polyphosphazene‐graft copolymers is prepared by cross‐linking reaction because the former material has good enough mechanical property, while the latter is excellent in the proton transfer. The cross‐linked membranes combine the advantages of the two kinds of polymers. Among them, the membrane poly[(4‐trifluoromethylphenoxy)(4‐methylphenoxy)phosphazene]‐g‐poly {(styrene)11‐r‐[4‐(4‐sulfobutyloxy)styrene]33‐sulfonated poly(ether ether ketone)75 (CF3‐PS11‐PSBOS33‐SPEEK75) shows a proton conductivity at 0.143 S cm−1 under fully hydrated conditions at 80 °C and performs tensile strength about five times as much as did the sulfonated polyphosphazene membrane CF3‐PS11‐PSBOS33. Further doping of sulfonated single‐walled carbon nanotubes (S‐SWCNTs) into the cross‐linked membranes on the screening of additives gives composite membrane CF3‐PS11‐PSBOS33‐SPEEK75‐SWCNT possessing proton conductivity of 0.196 S cm−1, even higher than that of Nafion 117 and a tensile strength comparable to that of Nafion 117. However, this significance of the composite membrane in the proton conduction is not observed in the test with a H2/air fuel cell when it shows a maximal power density of 280 mW cm−2 at 80 °C, whereas 294 mW cm−2 is observed for CF3‐PS11‐PSBOS33‐SPEEK75.
Polyethersulfone (PES) was sulfonated by chlorosulfonic acid and concentrated sulfuric acid. The pure sulfonated PES (SPES) and modified SPES membranes were prepared by blending with different charged surface modifying macromolecules (cSMMs) namely, SPES/DEG‐HBS, SPES/PEG‐HBS, and SPES/PPG‐HBS. Membranes were characterized for their morphology, physical properties, and electrochemical properties in order to evaluate these membranes as cation exchange membranes. The blended membranes showed an increase in hydrophilicity, water uptake, and proton conductivity compared to the pure SPES membranes. The highest values of water uptake and proton conductivity were obtained for the SPES/PPG‐HBS blended membrane. Morphological studies revealed that the nodule size and surface roughness also influenced the water uptake, apart from the additional –SO3H group. Among the modified membranes, the SPES/DEG‐HBS blended membrane exhibited a lower methanol permeability value of 8.895 × 10−8 cm2 s−1 than the corresponding SPES membrane. The other two cSMM blended membranes showed higher methanol permeability values than SPES but still a smaller value than Nafion 117. The highest selectivity ratio (i.e., ratio of proton conductivity to methanol permeability) was obtained with the SPES/DEG‐HBS cSMM blended membrane. These results showed that the SPES/cSMM blended membranes have promise for possible use as a cation exchange membrane in fuel cells and electrolyzer applications. 相似文献
Novel poly(benzimidazole/fluoro/ether/siloxane/amide) (PBFESA) was developed for the formation of hybrid proton exchange membrane. Afterward, phosphoric acid doped PBFESA/PS-S/SiNPs was prepared with PBFESA, sulfonated polystyrene (PS-S), and 0.1–2 wt% silica nanoparticles (SiNPs). Tensile strength of acid doped PBFESA/PS-S/SiNPs nanocomposites increased from 63.9 to 68.1 MPa with increasing SiNPs loading. They had higher ion exchange capacity (IEC) of 2.3–3.3 mmol/g and proton conductivity of 1.9–2.7 S/cm at 80°C (higher than perfluorinated Nafion 117 membrane 1.1 × 10?1 S/cm). A H2/O2 fuel cell using PBFESA/PS-S/SiNPs 2 (IEC 3.3 mmol/g) showed better performance than Nafion 117 at 40°C (30% RH). 相似文献