Protic and aprotic anionic oligomeric ionic liquids

We report on synthesis of linear and hyperbranched protic and aprotic anionic oligomeric ionic liquids (OlLs). alpha,omega-Dicarboxy- and alpha,omega-disulfooligo(ethylene oxide)s, alpha-carboxy- and alpha-sulfooligo(ethylene oxide monomethyl ether)s, and di[alpha-carboxyoligo(ethylene oxide monomethyl ether)] were synthesized using reaction of oligo(ethylene oxide diol) (MW 1000) and its monomethyl ether (MW 750) with phthalic-, 2-sulfobenzoic anhydride and pyromellitic dianhydride. Di- and mono-substituted anionic OlLs were prepared by neutralizing these compounds with N-methylimidazole. Aprotic anionic OlLs were synthesized by reaction of sodium salts of the prepared oligomeric di- and monoacids with 1,3-dimethyl imidazolium iodide. Hyperbranched protic and aprotic anionic OILS were prepared in a similar manner. The structure, thermal stability and ionic conductivity of the synthesized compounds in the range of 20-120 degrees C in anhydrous conditions is governed by the molecular architecture of the oligomeric chains and the type of the cation/anion moieties. OILS under study are amorphous at room temperature but some protic and aprotic linear-chain Ms prone to form a low melting temperature crystalline phase. The ionic conductivity of the synthesized OILS can be varied in broad range reaching 10(-3) S/cm value at temperatures over 100 degrees C under anhydrous conditions. (C) 2014 Elsevier Ltd. All rights reserved.