Durable Sulfonated Poly(arylene sulfide sulfone nitrile)s Containing Naphthalene Units for Direct Methanol Fuel Cells (DMFCs)

Abstract

1Sulfonated poly(arylene sulfide sulfone nitrile)s (SN) were synthesized to investigate the effects 2 of naphthalene units in the polymer backbone on membrane properties. The small and planar 3 naphthalene in the main chain induced semi-crystallinity in the polymer, as confirmed by 4 molecular simulations and wide angle X-ray diffraction patterns. The semi-crystalline SN 5 polymer membranes exhibited excellent chemical and mechanical properties, better than those of 6 their phenylene counterpart (SP). In particular, the water uptake and swelling ratio of the SN 7 membranes were much lower than those of the SP membranes. Furthermore, the SN membranes 8 exhibited a greatly reduced methanol permeability (9-17 × 10 -8 cm 2 s -1 ) compared to Nafion ® 9 117 (240 × 10 -8 cm 2 s -1 ) at 30 o C in 10 M methanol. Moreover, sulfide-and naphthalene-based 10 chemical structure and semi-crystalline nature of the SN membranes enhanced their DMFC 11 single cell performance and long-term stability during fuel cell operation. 12

Sulfonated polyimides containing triphenylphosphine oxide for proton exchange membranes

“…Water molecules lead to dissociation of the acid functionalities and facilitate proton transport in the PEM [28,29]. The water uptake values for this series of co-SPIs are low compared to other reported polyimide membrane [8] due to the presence of polar phosphine oxide moiety [21]. Generally, weight-based IECs (IEC W ) are reported most often, but to match with the realistic hydrated condition of the fuel cell and for more realistic comparison of WU among different membranes volumetric IEC (IEC V , mequiv cm À3 ), was also calculated and correlated with the volume-based water uptake (WU V ) Table 5 ( Fig.…”

“…It was also noticed that the DSDSA-based co-SPIs in TEA-salt form showed good solubility in m-cresol, but not in their proton form. The good solubility of the co-SPIs was due to the presence of phosphine oxide moiety and ether linkages in the polymer backbone [21,22].…”

“…Generally, weight-based IECs (IEC W ) are reported most often, but to match with the realistic hydrated condition of the fuel cell and for more realistic comparison of WU among different membranes volumetric IEC (IEC V , mequiv cm À3 ), was also calculated and correlated with the volume-based water uptake (WU V ) Table 5 ( Fig. 8), [21,30]. The highest water uptake (weight %) and water uptake (Vol %) was 41% and 52% at 80 C for the highest IEC W membrane TPPO-60 (IEC W ¼ 1.84), respectively.…”

“…In recent years, Watanabe et al reported that introduction of phenylphosphine oxide moiety in the polymer backbone gives outstanding oxidative stability and high proton conductivity [14]. In addition, it is reported that phenylphosphine oxide moiety provides excellent adhesive properties with the catalyst layer [21], with the added benefits of excellent thermal stability and miscibility because of strong hydrogen bonding [22,23]. The water uptake and swelling ratio of the membranes are also crucial factors which affect PEM Fuel cell performances since a high water uptake and swelling ratio increases fuel crossover and deteriorate the mechanical properties.…”

Side-chain-type clustered sulfonated poly(arylene ether ketone)s prepared by click chemistry

“…The water molecules are regarded as a transportation medium of protons. A lack of water uptake leads to a decrease of the proton conductivity [41]. However, excessive water uptake leads to fuel loss and induces poor copolymer strength.…”