SPEEK ketone

To date, much effort has been undertaken to develop new alternatives. For example, sulfonated aromatic polymers, i.e., polymers with the sulfonic acid groups directly attached to the main chain or carrying short pendant side chains with terminal sulfonic acid units, attract increasing interest because of their chemical and thermal stability, and the ease of the sulfonation procedure. Some of the proposed polymers are sulfonated polysulfone (SPSU) [134] sulfonated poly(phenylene oxide) (SPPO) [135] sulfonated poly-(ether ether ketone) (SPEEK) [136] poly(phenylquinoxaline) (PPQ) [137] and poly(benzeneimidazole) (PBI) [138],... 

Proton conductivity as a function of lEC for ETFE-g-PSSA = polyethylenetetrafluoroethylene-gra/t-polystyrene sulfonic acid, BAM membrane = substituted poly(trifluorostyrene) sulfonic acid, SPEEK = sulfonated poly(ether ether ketone) and Nafion. (From Peckham, T. J. et al. 2007. Journal of Materials Chemistry 17 3255-3268, and Dolye, M. et al. 2001. Journal of Physical Chemistry B 105 9387-9394.)... 

Sulfonated poly(arylene ether)s (SPAEKs) have also been developed for application in PEMs, with sulfonated poly(ether ether ketone) (SPEEK) (9a) as the archetypical example of this group. The base polymer of SPEEK is commercially available and relatively cheap, and sulfonation is a straightforward procedure using concentrated sulfuric acid. At sufficient levels of sulfonation, proton conductivity values for SPEEK are comparable to or higher than those of Nafion. However, this does lead to random copolymers where there... 

One of the first examples of this type of blend was composed of SPEEK or SPES as the acidic component and diaminated PES, poly(4-vinylpyridine) (P4VP), poly(benzimidazole) (PBl), or poly(ethyleneimine) (PEI) as the basic component. " For blend lEC values of 1.0 meq/g, conductivity values were reported to be good, as was H2/O2 EC performance. Thermal stabilities for these blends was also demonstrated to be high (>270°C). Other examples of acid-base PEMs include blends of SPPO and PBI, sulfonated poly(phthalazinone ether ketone) and aminated SPES, SPIs and aminated Pls, and SPEEK with PES bearing benzimidazole side groups, ° as well as an unusual example in which the blend is composed of sulfonated, hyper-branched polyether and pyridine-functionalized polysulfone. ... 

Zhang et al. [128] synthesized a self-humidifying membrane based on a sulfonated poly(ether ether ketone) (SPEEK) hybrid with a sulfated zirconia (SO / ZrO2, SZ) -supported platinum catalyst (Pt-SZ catalyst). This type of composite membrane has a higher proton conductivity than plain SPEEK, due to the effect of the Pt-SZ catalyst the membrane also provided excellent single cell performance at low humidity. 

Sulfonated poly(ether ether ketone) (SPEEK)... 

C. Zhao, Z. Wang, D. Bi, H. Lin, K. Shao, T. Fu, S. Zhong, and H. Na Blend membranes based on disulfonated poly(aryl ether ether ketone)s (SPEEK) and poly(amide imide) (PAI) for direct methanol fuel cell usages. Polymer, 48(11) 3090-3097, May 2007. 

The investigation of different variants of sulfonated polyetherketones has been widely described in the literature polyetherketone [188], poly(ether ether ketone) [189-191], poly(ether ketone ketone) [192] and poly(ether ether ketone ketone) (sPEEKK) [193, 194], poly(oxa-p-phenylene-3,3-phthalido-p-phenylene-oxa-p-phe-nyleneoxy-phenylene) (PEEK-WC) [195]. An interesting comparison between different structures in this class of material (sulfonated poly (ether ether ketone) (sPEEK) and poly(phenoxy benzoyl phenylene)) (sPPBP) has been published by Rikukawa and Sanui [196]. Both polymers are isomers. In sPEEK the sulfonic groups are in the main chain, while in sPPBP they hang in a side chain. The water uptake at low relative humidity is higher for sPPBP as well as the conductivity at high temperatures. 

Bowen et al. [40] used sulfonated poly(ether ether ketone) (SPEEK) as an additive in the polysulfone (PSf)/SPEEK/N-methyl-2-pyrrolidone (NMP) system. Membrane characterization was carried out using filtration studies and AEM. Membranes prepared from solutions in the region of polyelectrolyte behavior [41] showed more pronounced and systematic improvement of membrane permeability and salt rejection. A small decrease in pore size and surface roughness was also followed by an increase in SPEEK content. Compared with a - 28.5 mN m adhesion force of a 4 pm silica particle for a SPEEK free PSf membrane, a SPEEK modified membrane showed greatly reduced adhesion of - 0.75 mNm h This, together with the surface smoothening effect, leads to the reduction of membrane fouling when the surface is modified by the addition of SPEEK. 

In another study, Bowen et al. [42] prepared membranes from polymer blends of polysulfone and sulfonated poly(ether ether ketone) (PSf/SPEEK). It was reported that these membranes had high porosities, high charge densities, and pore sizes at the boundary between NF and UE For comparison, two commercial membranes of cellulose acetate and poly(ether sulfone) were chosen. Therefore, the following four membranes were involved in their study ... 

Figure 4.28 AFM image of (a) GO- and (b) stdphonated poly-ether-ether ketone (SPEEK)-modified graphene (reprinted from [158] with permission from American Chemical Society).

The acid-base Nafion composite membranes include blends of Nafion with polypyrrole (PPy) [98-104], polybenzimidazole (PBI) [105-107], poly (propyleneoxide) (PPO) [108, 109], polyfurfuryl alcohol (PFA) [110], poly(vinyl alcohol) (PVA) [111-115], sulfonated phenol-formaldehyde (sPF) [116], polyvinylidene fluoride (PVdF) [117-122], poly(p-phenylene vinylene) (PPV) [123], poly(vinyl pyrrolidone) (PVP) [124] polyanifine (PANI) [125-128], polyethylene (PE) [129], poly(ethylene-terephtalate) [130], sulfated p-cyclodextrin (sCD) [131], sulfonated poly(ether ether ketone) (sPEEK) [132-135], sulfonated poly(aryl ether ketone) (sPAEK) [136], poly(arylene ether sulfone) (PAES) [137], poly(vinylimidazole) (PVl) [138], poly(vinyl pyridine) (PVPy) [139], poly (tetrafluoroethylene) (PTFE) [140-142], poly(fluorinated ethylene-propylene) [143], sulfonated polyhedral oligomeric silsesquioxane (sPOSS) [144], poly (3,4-ethylenedioxythiophene) (PEDT) [145, 146], polyrotaxanes (PR) [147], purple membrane [148], sulfonated polystyrene (PSSA) [149, 150], polystyrene-b-poly(ethylene-ran-butylene)-bpolystyrene (SEES) [151], poly(2-acrylamido-2-methyl-l-propanesulphonic acid-co-l,6-hexanediol propoxylate diacrylate-co-ethyl methacrylate) (AMPS) [152], and chitosan [31]. A binary PVA/chitosan [153] and a ternary Nafion composite with PVA, polyimide (PI) and 8-trimethoxy silylpropyl glycerin ether-1,3,6-pyrenetrisulfonic acid (TSPS) has also been reported [154]. 

Sulfonated poly(arylene ether)s (sPAE)s, such as sulfonated poly(ether ether ketone) (sPEEK) (see Fig. 6.7) are promising ionomer for DMFC [181] due to their chemical stability, possibility of structural variants, and sulfonatiOTi procedures, as discussed by Kim et al. [7]. 

The development of polyaryls, in particular polyetherketones (PEEK), as a substitute of perfluorinated polymers was mainly based on cost and stability considerations [1]. Sulfonated polyetherketones has been found to be durable under fuel cell operation conditions over several thousand hours [185]. Victrex Company is the main producer of PEEK polymer and its sulfonation can be performed directly on the polymer backbone or by polymerization of sulfonated monomers [7]. Hoechst-Aventis and Eumatech commercialize sulfonated PEEK (sPEEK) and sulfonated poly(phtalazinone ether ketone) (sPPEK) membranes for fuel cell applications [3]. 

Zhang N, Zhang G, Xu D, Zhao C, Ma W, Li H, Zhang Y, Xu S, Jiang H, Sun H, Na H (2011) Cross-linked membranes based on sulfonated poly (ether ether ketone) (SPEEK)/Nafion for direct methanol fuel cells (DMFCs). Int J Hydrogen Energ 36 11025-11033... 

Gao Q, Wang Y, Xu L, Wei G, Wang Z (2009) Proton-exchange sulfonated poly(ether ether ketone) (SPEEK)/SiOx-S composite membranes in direct methanol fuel cells. Chinese J Chem Eng 17 207-213... 

Gosalawit R, Chirachanchai S, Shishatskiy S, Nunes SP (2008) Sulfonated montmorillonite/ sulfonated poly(ether ether ketone) (SMMT/SPEEK) nanocomposite membrane for direct methanol fuel cells (DMFCs). J Membr Sci 323 337-346... 

Li X, Liu C, Xu D, Zhao C, Wang Z, Zhang G, Na H, Xing W (2006) Preparation and properties of sulfonated poly(ether ether ketone)s (SPEEK)/polypyrrole composite membranes for direct methanol fuel cells. J Power Sources 162 1-8... 

Nafion membranes, as discussed, have been intensively used for fuel cells because they show high proton conductivity and chemical stability, but their methanol permeability is too high. However, the critical aspect of Nafion is still its high cost. Several nonfluorinated membranes, with potentially lower costs, have been tested for fuel cells. Sulfonated PSF, sulfonated poly(ether ether ketone) (SPEEK), sulfo-nated polyphosphazene, and sulfonated polyamides (PA) with good performance for hydrogen fuel cells are described in several reports (Savadogo 1998 Zaidi et al. 2000 Guo et al. 1999 Vallejo et al. 1999). However, the methanol permeability in many cases is still relatively high. 

The presence of the nonpolar and polar moieties has led to phase segregation, which is desirable for transport properties. The higher phase segregation in Naflon has created broader water channels with fewer dead ends and thus more interconnected channels. With the presence of water, this microstructure transports water and proton better, which confers on Naflon a high proton conductivity when fully hydrated. However, this microstructure is a drawback for the methanol crossover, which is also very high, to a greater amount than that of sulfonation of poly(ether ether ketone) (SPEEK). 

Yang and Manthiram studied SPEEK membranes for use in a DMEC (Yang and Manthiram 2003). It was reported that a membrane with 50% degree of sulfonation (DS) exhibited comparable DMEC performance to Naflon 115 at 65°C, while the methanol crossover was two times lower than the Naflon membrane. Sulfonated poly(ether ketone) (SPEK), sulfonated poly(ether ketone ketone) (SPEKK), and sulfonated poly(ether ether ketone ketone) (SPEEKK) come from the same family as SPEEK and therefore their characteristics are quite similar. 

The sulfonation of poly(ether ether ketone) is similar to the sulfonation technique for PSSA using sulfonation agents such as high concentration of sulfuric acid. The DS of SPEEK can be controlled by varying the reaction time and temperature (Xing et al. 2004). The work of Lee et al. showed that the proton conductivity of the SPEEK membrane increased with DS (Lee et al. 2007). The increase in DS will increase the hydrophilicity and water uptake and, consequently, gives an opportunity for the formation of water-mediated pathways for protons. Methanol permeability measurement indicates that its rate increases with the increase of DS but at a much lower rate than the Naflon membrane. This is due to the difference in their microstructures (Li et al. 2003a). 

He, T., Frank, H., Mulder, M.H.V. and Wessling, M. 2008a. Preparation and characterization of nanofiltration membranes by coating polyethersulfone hollow fibers with sulfonated polyfether ether ketone) (SPEEK). 307 62-72. 

SMA Styrene-co-maleic anhydride SPEEK Sulfonated poly(ether ether ketone) TGA Thermogravimetric analyzer TMOS Tetramethyl bisphenol A oligosulfones UCST Upper critical solution temperature... 

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