Sulfonated poly-styrene membranes

The importance of the choice of casting solvent on membrane properties is also evident in studies of proton conductivity of sulfonated poly-styrene-foZock-(ethylene-co-butylene)-fc/ock-sulfonated polystyrene (SSEBS) (Scheme 2c) membranes prepared from different compositions of mixed casting solvents (MeOH/THF) (Fig. 25). For example, the conductivity of SSEBS membranes possessing a degree of sulfonation (DS) of 27 mol % increases with an increasing fraction of methanol in the solvent mixture. For membranes with a DS of 42 mol %, the proton conductivity increases with concentration of methanol fraction and levels off at higher volume fraction. 

A PVDF-HFP/PSSA composite membrane was tested in DMFC [490] reaching 80 mW.cm at 60 °C. When Si02 was added to the composite the MPD increased up to 110 mW.cm at the same temperature, which represents the best DMFC performance for a PVDF-based membrane. Recently, a composite of PVDF with sulfonated poly(styrene-b-ethylene butylenes-b-styrene) (sPSEBS) was reported to deliver up to 72 mW.cm at 60 °C in a DMFC, although the characteristics of the catalysts and the MEA were not described [491]. 

Carbide-derived earbons (CDCs) Degree-of-sulfonation (DOS) Direet assembly method Eleetrode materials Metallie eleetrode materials Nonmetallie eleetrode materials Freeze-dried baeterial eellulose (FDBC) Graphene-Nation polymer aetuator Impregnation-reduetion method Ionie polymer-metal eom-posites (IPMCs) Biopolymer membrane materials Eleefromeehanieal properties of Metallie eleetrode materials Nanoearbon-eomposite membrane materials Nonmetallie eleetrode materials Sulfonated bloek eopolymer membrane materials Sulfonated hydroearbon baekbone membranes Pendent sulfonated ehitosan (PSC) Polyaniline (PANI) Sulfonated poly(amie aeid) (SPAA) Sulfonated poly(styrene-ran-ethylene) (SPSE) Sulfonated polyimide (SPI)... 

Wang XL, Oh IK, Chen TH (2010a) Electro-active polymer aetuators employing sulfonated poly (styrene-ran-ethylene) as ionic membranes. Polym Int 59(3) 305 312 Wang XL, Oh IK, Lee S (2010b) Electroactive artificial muscle based on crosslinked PVA/SPTES. Sensor Actuators B 150(l) 57-64... 

N. Carretta, V. TricoU, E. Picchioni, lonomeric membranes based on partially sulfonated poly(styrene) Synthesis, proton conduction and methanol permeation. J. Membr. Sci. 166, 189-197 (2000). 

The basic concept to use block co-polymer for the application to the DMFC is that ordered hydrophilic/hydrophobic phase separations offer a route for the selective transport of proton ions with reduced methanol crossover in the hydrophilic domains, because block co-polymers can be selectively sulfonated using post-sulfonation methods, and the block co-polymers can be verified over a wide range of structures during anionic polymerization. For example, methanol transport behaviors of a triblock co-polymer ionomer, sulfonated poly(styrene-isobutylene-styrene) (S-SIBS), were compared with Nafion to determine whether the sulfonated block co-polymer could serve as a viable alternative membrane for application to the DMFC [62]. The S-SIBS membranes showed approximately 5-10 times more methanol selectivity than that of Nafionll , although the S-SIBS membranes exhibited low conductivity compared with Nafion 117. 

Very early hydrocarbon-based membranes tested as electrolytes in PEMECs for Gemini space missions, such as sulfonated phenol-formaldehyde resins, sulfonated poly(styrene-divinylbenzene) copolymers, and grafted polystyrene sulfonic acid membranes, were chemically weak, and therefore PEMFCs using these membranes showed poor performance and had only lifetimes of several hundred hours (LaConti et al. 2003). Nafion , a PESA membrane, was developed in the mid-1960s by DuPont (LaConti et al. 2003). It is based on an aliphatic perfluorocarbon sulfonic acid, and exhibited excellent physical properties and oxidative stability in both wet and dry states. A PEMEC stack using Nafion 120 (250- tm thickness, equivalent weight = 1,200) achieved continuous operation for 60,000 h at 43-82°C (LaConti et al. 2003, 2006). A Nafion -based PEMFC was used for the NASA 30-day Biosatellite space mission (LaConti et al. 2003). 

Sulfonated poly(styrene-co-maleic anhydride)-poly(ethylene glycol)-silica nanocomposite polyelectrolyte membranes for fuel cell applications. 

A. Saxena, B.P. Tripathi, V.K. Shahi, Sulfonated poly(styrene-co-maleic anhydride)-poly(ethylene glycol)-silica nanocomposite polyelectrolyte membranes for fuel ceU applications,/. Phys. Chem. B, 111 (2007) 12454—12461. 

Electrochemical membrane reactors have also been used in fine chemistry reactions. The electrochemical reduction of maleic acid to succinic add has been reported by using a sulfonated poly(styrene divinylben-zene) membrane intercalated between copper and lead anodes, assembled in a continuous contactor-type membrane reactor. Montiel et al. have recently described the use of MEA technology for the synthesis of N-acetyl-L-qrsteine by electroreduction of N,N-diacetyl-L-qrstine. 

Water-insoluble PEC were prepared by mixing oppositely charged polyelectrolytes, e.g. DEAE dextran with CMD [340,341], sodium dextran sulfate, poly(styrene sulfonate) (NaSS) [342], poly(sodium L-glutamate) (PSLG), poly(vinyl alcohol)sulfate [343], or potassium metaphosphate (MPK) [240]. They are useful as membranes or in biomedical applications [343,344]. 

M. Elomaa, S. Hietala, M. Paronen, N. Walsby, K. Jokela, R. Serimaa, M. Torkkeli, T. Lehtinen, G. Sundhohn and F. Sundhohn. The state of water and the nature of ion clusters in crosslinked proton conducting membranes of styrene grafted and sulfonated poly(vinylidene fluoride). Journal of Materials Chemistry 10, 2678-2684 2000. 

Insoluble polyelectrolyte complex may be formed when dissolved acidic and basic polyelectrolyte polymers are brought into intimate contact (131). Complex formation is generally agreed to be driven by the increase in entropy associated with the loss of small counterions into the bulk of the solution (132). Polyelectrolyte complex from concentrated solutions of strongly acidic and basic homopolymers has been shown to form sufficiently rapidly to produce a 20-30 nm thick membrane at the solution interface, as was found through reaction of dissolved poly(vinylbenzyl trimethylammonium chloride) with sodium poly (styrene sulfonate) (132). 

For polysalt amphoteric membranes, a cationic polyelectrolyte solution such as poly(benzyl trimethylammonium salt) and an anionic polyelectrolyte solution such as poly(styrene sulfonate) are mixed and a polymer salt precipitated. The polymer salt is then dissolved in a suitable solvent and is formed into a membrane by a casting method.103... 

Figure 5.26 Relationship of Pa50 to the concentration of 1 1 mixed salt solutions of sodium sulfate and sodium chloride using anion exchange membranes with and without anionic polyelectrolyte layers. (O) without the layer ( ) immersed in 1000ppm poly(styrene sulfonic acid) (reduced viscosity of 1.0% solution, r sp/C 0.714 dlg ) solution (X) with 1000ppm polycondensation product of sodium naphthalene sulfonate and formaldehyde (MW ca. 1000) solution. After an anion exchange membrane (NEOSEPTA AM-1 strongly basic anion exchange) had been immersed in the anionic polyelectrolyte solution for 17 h at 25.0 °C, 1 1 mixed salt solutions of sodium sulfate and sodium chloride were electrodialyzed for 60 min at 25.0 °C under vigorous agitation.

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