Protic and aprotic anionic oligomeric ionic liquids V.V. Shevchenko a, * , A.V. Stryutsky a , N.S. Klymenko a , M.A. Gumenna a , A.A. Fomenko a , V.N. Bliznyuk b , V.V. Trachevsky c , V.V. Davydenko a , V.V. Tsukruk d a Institute of Macromolecular Chemistry of The National Academy of Sciences of Ukraine, Kharkivske Shosse 48, Kiev 02160, Ukraine b Department of Materials Science and Engineering, Clemson University, Clemson, SC 29634, USA c Technical Center of The National Academy of Sciences of Ukraine, ul. Pokrovska 13, Kiev 04070, Ukraine d School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245, USA article info Article history: Received 15 December 2013 Received in revised form 11 April 2014 Accepted 13 April 2014 Available online xxx Keywords: Oligomeric ionic liquids Linear and hyperbranched ionic liquids Structure abstract We report on synthesis of linear and hyperbranched protic and aprotic anionic oligomeric ionic liquids (OILs). a,u-Dicarboxy- and a,u-disulfooligo(ethylene oxide)s, a-carboxy- and a-sulfooligo(ethylene oxide monomethyl ether)s, and di[(a-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 OILs were prepared by neutralizing these compounds with N-methylimidazole. Aprotic anionic OILs were syn- thesized 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 20e120  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 OILs 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  C under anhydrous conditions. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Organic ionic liquids (IL) represent a new class of electrolytes and are attractive both as a fundamental research field and for practical applications. The practical interest to these compounds is due to their inherently high chemical and electrochemical stability, low flammability, low saturated vapor pressure, and high ionic conductivity. Recent developments of the ionic liquids with polymerizable components have enabled synthesis of polymer ionic liquids, which combine the unique properties of low molecular mass ionic liquids with the macromolecular properties of traditional polymers. This has already led to creation of a new class of polymer electrolytes with a number of pro- spective applications, which have been highlighted in several recent reviews [1e 7]. The papers consider design of cationic, anionic and zwitterionic polymeric ionic liquids (PIL) for creation of various functional materials [2,4,5,7]. Particularly, cationic polymers [6] and their sub-class of imidazolyl-containing PILs [3] have been discussed in details. It should be mentioned that the method of synthesis of polymeric ionic liquids through poly- merization of monomeric ionic liquid compounds having a car- bonecarbon double bound in their structure is the most developed so far [7]. Due to a hydrophobic character of typical counter-ions constituting ionic liquids most of the PILs do not dissolve in wa- ter. They are, nevertheless, soluble in polar organic solvents that distinguish them from classic (i.e., water soluble) electrolytes [4]. Such compounds are losing their low melting transition point property and ability to exist in a liquid state over a broad tem- perature range when polymerized [4,5]. Therefore, they rather should be considered as polymeric analogs of traditional ionic liquids [8]. However, there are polyacrylate anionic ILs which remain in a liquid state within the range from room temperature to 220  C thus enabling its application as a solvent and reaction medium [9]. Polymer chemistry distinguishes oligomer materials as a special state of macromolecular compounds [10]. Thus, combining * Corresponding author. Tel.: þ380 44 559 5500; fax: þ380 44 292 4064. E-mail addresses: valshevchenko@yandex.ru, valery_petr@i.ua (V. V. Shevchenko). Contents lists available at ScienceDirect Polymer journal homepage: www.elsevier.com/locate/polymer http://dx.doi.org/10.1016/j.polymer.2014.04.020 0032-3861/Ó 2014 Elsevier Ltd. All rights reserved. Polymer xxx (2014) 1e11 Please cite this article inpress as: Shevchenko VV, et al., Protic and aprotic anionic oligomeric ionic liquids, Polymer (2014), http://dx.doi.org/ 10.1016/j.polymer.2014.04.020