Sulfonated polyether ether ketone polymer

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. 

S. M. J. Ztiidi, S. D. Mikhailenko tmd S. Kaliaguine, Sulfonated polyether ether ketone based composite polymer electrolyte membranes, Catal. Today 67, 225-236 (2001). 

S. M. J. Zaidi, S. D. Mikhailenko and S. Kaliaguine, Electrical properties of sulfonated polyether ether ketone/polyetherimide blend membranes doped with inoigtmic acids, J. Polymer Sci. B Polym. Phys. 38, 1386-1395 (2000). 

Kumar, R., Mamlouk, M., Scott, K., Sulfonated polyether ether ketone-sulfonated graphene oxide composite membranes for polymer electrolyte fuel cells, RSC Adv., 2014, 4, 617-623. 

Sulfonation is very useful chemical modification of polymer, as it induces high polarity in the polymer changing its chemical as well as physical properties. Sulfonated polymers are also important precursors for ionomer formation [75]. There are reports of sulfonation of ethylene-propylene diene terpolymer (EPDM) [76, 77], polyarylene-ether-sulfone [78], polyaromatic ether ketone [79], polyether ether ketone (PEEK) [80], styrene-ethylene-butylene-styrene block copolymer, (SEBS) [81]. Poly [bis(3-methyl phenoxy) phosphozene] [82], Sulfonated polymers show a distinct peak at 1176 cm"1 due to stretching vibration of 0=S=0 in the -S03H group. Another peak appears at 881 cm 1 due to stretching vibration of S-OH bond. However, the position of different vibrational bands due to sulfonation depends on the nature of the cations as well as types of solvents [75, 76]. 

Fortunately, the deficiencies of both the classic thermosets and general purpose thermoplastics have been overcome by the commercialization of a series of engineering plastics including polyacetals, polyamides, polycarbonate, polyphenylene oxide, polyaryl esters, polyaryl sulfones, polyphenylene sulfide, polyether ether ketones and polylmides. Many improvements in performance and processing of these new polymers may be anticipated through copolymerization, blending and the use of reinforcements. 

Fig. 19.1 The plastics pyramid according to thermal literature data of common polymers preferred materials for HT-PEM applications are in the upper right region TPI thermoplastic polyimide, PES polyether sulfone, P P)SU poly(phenylene)sulfone, PE E)K polyether(ether) ketone, LCP liquid crystal polymer, e.g., Vectra, PPS polyphenylene sulfide, PTEE polytetrafluoroethylene.

High-performance engineering thermoplastics have recently assumed hicteas-ing importance due to their exceptional properties at elevated tenqioatures. A number of such spedalty polymers has been introduced into the market for higili-temperature applications and examples of some of the outstanding ones are poly phenylene oxide (PPO), poly fdienylene sulfide (PPS), polyetlier sulfone ES), polyaryl sulfone (PAS), polyether ether ketone (PEEIQ, polyetherimide (PEl, and polyarylate (PAr). 

Most polymers used today are thermoplastics. Poiypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and polystyrene (PS) often find application as low-end consumer items, packaging or others. Technical parts are produced mostly from acrylonitrile-butadiene-styrene-copolymer (ABS), polyamide (PA), polybutylene terephthalate (PBT), polyoxymethylene (POM), polyether sulfone (PES), polycarbonate (PC), polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), or polyimide (PI). Polyvinyl chloride (PVC) is a material often used in building construction, especially for roofing membranes, window frames, and pipes, and its properties (rigid or flexible) are generally modified by additives. 

Aromatic polymers have many desirable properties such as good lap shear strength, thermal stabihty, and tensile strength, which make them useful for a wide variety of applications. The term aromatic polymer is used herein to mean a polymer, which has aromatic groups incorporated in the repeat unit of their backbone chain. Such polymers include polyimides (Pis), polyetherimides, polysulfones, polyether sulfones, polyaryl ether ketones, polycarbonates, poly-arylates, and the like [20]. 

Polymerization Solvent. Sulfolane can be used alone or in combination with a cosolvent as a polymerization solvent for polyureas, polysulfones, polysUoxanes, polyether polyols, polybenzimidazoles, polyphenylene ethers, poly(l,4-benzamide) (poly(imino-l,4-phenylenecarbonyl)), sUylated poly(amides), poly(arylene ether ketones), polythioamides, and poly(vinylnaphthalene/fumaronitrile) initiated by laser (134—144). Advantages of using sulfolane as a polymerization solvent include increased polymerization rate, ease of polymer purification, better solubilizing characteristics, and improved thermal stabUity. The increased polymerization rate has been attributed not only to an increase in the reaction temperature because of the higher boiling point of sulfolane, but also to a decrease in the activation energy of polymerization as a result of the contribution from the sulfonic group of the solvent. 

In addition to Nafion-based catalyst layers, additional types have been developed, including CLs with different ion exchange capacities (lECs) [57,58] or with other hydrocarbon-type ionomers such as sulfonated poly(ether ether ketone) [58-60], sulfonated polysulfone [61,62], sulfonated polyether ionomers [63], and borosiloxane electrolytes [64], as well as sulfonated polyimide [65]. These nonfluorinated polymer materials have been targeted to reduce cost and/or increase operating temperature. Unfortunately, such CLs still encounter problems with low Pt utilization, flooding, and inferior performance compared wifh convenfional Nafion-based CLs. 

Fra Francis, B., Thomas, S., Thomas, S. P., Ramaswamy, R., Rao, V. L. Diglycidyl ether of bisphe-nol-A epoxy resin-polyether sulfone/polyether sulfone ether ketone blends phase morphology, fracture toughness and thermo-mechanical properties. Colloid Polym. Sci. 285 (2006) 83-93. 

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