Sulfonated polyether ether ketone SPEEK

Figure 7.16 Water uptake in sulfonated polyether-ether ketone (SPEEK) +Ti02 nanocomposite membranes as a function of the filler content. 0 refers to the untreated T1O2,1 to the dopamine-treated Ti02, and 2 to the polyethylene-imine-treated T1O2.

It has been suggested that instead of membranes made from perfluorinated sulfonic acids (PFSAs), membranes be used made from other, heat-resistant polymers containing the sulfonic acid group. One could think here of sulfonated polyimides (SPIs) and sulfonated polyether ether ketones (SPEEKs). Membranes made from such polymers have a sufficiently high protonic conductivity at elevated temperatures but are less sensitive to lower humidities and water loss. 

Another intrinsic approach has been proposed by Li et al. (2010). This time, the polymer network itself was used to heal the hydrophobicity by molecule displacement. The coating employed was made using layer-by-layer deposition of poly(allylamine hydrochloride) (PAH) with sulfonated polyether-ether-ketone (SPEEK) and polyacrylic acid (PAA) with final addition of lH,lH,2H,2H-perfluorooctyltriethoxysilane (POTS) by chemical vapour deposition (CVD) on the PAH-SPEEK/PAA coating. After removal of surface layers by O2 plasma, hydrophobicity was restored as a function of time and relative ambient humidity. 

DCM, dichloromethane DMA, N,N dimethylacetamide DMF, N,N dimethylformamide NMP, l-methyl-2-pyiTolidone PDMS, polydimethylsiloxane PI, phase inversion PVDF, polyvinylidene fluoride RH, relative humidity SD, spinodal decomposition SE, solvent evaporation SPEES-WC, sulfonated polyetherethersulfone with cardo group SPEEK, Sulfonated polyether ether ketone TBABr, tetrabutilamonium bromide VIPS, vapor-induced PS. 

Fig. 7.11 Effect of different HPAs on the proton conductivity of composite membranes as a function of temperature. The sulfonation degree for the SPEEK was 70%. Reprinted with permission from Ref. [24] S. M. J. Zaidi, et al., Proton conducting composite membranes from polyether ether ketone and heteropolyacids for fuel cell applications, J. Membn Scl 173,17-34 (2000). Copyright Elsevier...

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. ... 

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