Sulfonated fluorinated PAEs

Kim and coworkers [137] prepared sulfonated fluorinated PAEs containing naphthalene moieties in the main chain (SPAE-XX, where XX = 20,30,40,50,60, 70, and 80) with DS=0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.8. The sulfonic acid groups were a bonded meta- to et/ier-linkage of a naphthalene ring in the polymer. The -CF3 groups were introduced into the polymer structure by using 6F-BPA units that controlled the sulfonic acid content in the copolymer composition. 

Scheme 2.40 Structure of densely sulfonated fluorinated PAEs containing phenylene ether units. Taken from Ref. [173].

S.4 Sulfonated Fluorinated PAEs with Side Chain Grafting... 

Guiver et al. [179] synthesized comb-shaped densely sulfonated fluorinated PAEs with four sulfonic acid groups S4-PAES-xx (where xx = 30, 40, and 50) as grafted side chains (Scheme 2.46). The sulfonated copolymer S4-PAES-40 exhibited high proton conductivity of 96mS/cm, comparable to Nafion (125mS/cm) at 80 °C. The methanol permeability value of S4-PAES-40 was 3.40x lO cm /s, which was several times lower than Nafion 117 (1.55x 10 cm2/s). 

Quatemized PAES with up to two pendant quaternary ammonium groups have been prepared by a cesium carbonate mediated direct aromatic nucleophihc subshtuhon polycondensahon of 2,2 -dimethylaminemethylene-4,4 -biphenol, 4,4 -biphenol, and 4,4 -difluorodiphenyl sulfone, followed by the reaction with iodomethane [96]. These types of ionomers are more stable than some fluorinated PAES ionomers under highly basic conditions. 

For PV application, fluorinated poly(arylene ether sulfone)s containing bulky cardo moiety and -CF3 groups have shown improvement in flux and separation factor owing to the increase in FFV and micro-phase-separated morphology allowing penetration of solvents into the membranes. However, fluorinated PAEs with various architectures need to be further explored for PV application. 

In an analogous reaction, bis-(pentafluorophenyl)-sulfone is used for the preparation of poly(arylene ether sulfone) (PAES). Bis-(pentafluoro-phenyl)-sulfone is prepared by the oxidation of bis-(pentafluorophenyl)-sulfide. In the next step, 3-ethynylphenol or 4-(phenylethynyl)phenol is attached to the PSI, or PAES. These groups are capable of thermal cross-linking. Fluorinated PSI or PAES can be used for optical waveguide applications. 

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]. 

Hydrophilic-hydrophobic alternating PAES multiblock copolymers have been prepared from partly fluorinated hydrophobic poly(arylene ether ketone) oligomers and disulfonated hydrophilic poly(arylene ether sulfone) telechelic oligomers [111]. 

Scheme 2.51 Structures of fluorinated aromatic poly(arylene ether) (PAE) with naphthalene moiety (PAE-NA) and biphenol moiety (PAE-BP) with pendant perfluoroalkyl sulfonic acid groups. Taken from Ref [184],...

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