A series of novel fully aromatic poly(arylene ether sulfone)s that contain 1,3,5-s-triazine groups were synthesized by the reaction of triazine-containing bisphenols with bis(4-fluorophenylsulfone) to study the effects of branching groups on solubility as well as thermal and mechanical properties. Polymers had inherent viscosities from 0.43 to 1.10 dL/g, thermal stabilities >500 °C in air, glass transition temperatures from 136 to 289 °C, and good film forming abilities. The polymer with pendant diphenylamine groups on the triazine ring were further investigated for use in proton exchange membranes based on solubility, thermo-oxidative stability, and ease of monomer synthesis. A series of copolymers made from 4,6-bis(4-hydroxyphenyl)-N,N-diphenyl-1,3,5-triazin-2-amine and 4,4′-biphenol were sulfonated with chlorosulfonic acid to achieve ion exchange capacities up to 2.62 mmol/g. The homopolymer was sulfonated exclusively on the diphenylamine branch and had the highest proton conductivity (0.11 S/cm at 95 °C and 100% relative humidity), even though it had the lowest water uptake and ion exchange capacity. Unsulfonated polymers and sulfonated copolymers showed little uptake of phosphoric acid. However, the sulfonated homopolymer with pendant diphenylamine groups had a 200-250 wt % uptake when soaked in 85% H 3 PO 4 at 90 °C, but the proton conductivity of this polymer was lower than the hydrated polymer without H 3 PO 4 added.

A highly cross-linked polyimide-poly͑ethylene oxide͒ copolymer has been synthesized that is capable of holding large volumes of liquid component, simultaneously maintaining good dimensional stability. An amine end capped oligomer was made that was imidized in solution, followed by reaction with a triisocyanate in the presence of desired additives at ambient temperature. Polymer films are able to hold over 4 times their weight in room temperature ionic liquid ͑RTIL͒ or carbonate solvent. Electrolytes were studied that contained varying amounts of RTIL, lithium trifluoromethanesulfonimide ͑LiTFSi͒, and alumina nanoparticles. Electrochemical stability of these electrolytes with lithium metal electrodes was studied by galvanic cycling and impedance spectroscopy. Improved cycling stability and decreased interfacial resistance were observed when increasing amounts of RTIL and LiTFSi were added. The addition of small amounts of alumina further decreased interfacial resistance by nearly an order of magnitude. During the course of the study, cycling stability increased from Ͻ3 to Ͼ1000 h at 60°C and 0.25 mA/cm 2 current density.As lithium batteries continue to increase in popularity, researchers continue to search for ways to improve battery safety without sacrificing performance. A major safety concern arises from the volatility and flammability of cyclic and acyclic carbonate solvents that are used in most batteries. 1 An ideal replacement would be solid polymer electrolytes, which would permit the use of lithium metal anodes and increase design flexibility, in addition to removing flammability concerns. 2 However, polymer electrolytes appear to have reached an upper conductivity limit of 10 −4 S/cm at room temperature, at least an order of magnitude lower than what is needed for practical use. 3 Researchers have recently addressed the flammability issue by replacing solvent with room temperature ionic liquids ͑RTILs͒ as liquid 4-7 and gel 8-16 electrolytes. RTILs are nonvolatile, nonflammable, highly conductive, and have a wide electrochemical stability window. 17 Howlett and co-workers 5 report a study of 0.5 mol/kg lithium trifluoromethanesulfonimide ͑LiTFSi͒ in N-butyl-Nmethylpyrrolidinium trifluoromethanesulfonimide ͑P 14 ͒, and N-propyl-N-methylpyrrolidinium trifluoromethanesulfonimide ͑P 13 , Scheme 1͒ as a liquid electrolyte. They report that this solution has a conductivity Ͼ10 −3 S/cm and a stable potential window from −0.6 to 4 V vs Li/Li + . They also demonstrate high cycling efficiencies in a Li/IL soln/Pt cell at 50°C.Shin and co-workers 18-22 studied polymer electrolytes formulated from poly͑ethylene oxide͒ ͑PEO͒, LiTFSi, and P 13 . They report stable galvanostatic cycling for their polymer electrolytes between Li electrodes at 60°C and a current density of 0.2 mA/cm 2 ͑3 h steps͒. P 13 alone is reactive with lithium metal. 20 However, when a small amount of LiTFSi is added, a stable interfacial layer is formed that protects P 13 from further degradation. When PEO is added, the amount of LiTFSi required t...

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