Journal of Polymer Science Part A: Polymer Chemistry, Vol.51, No.1, 190-202, 2013
Ethylene glycol-based ionic liquids via azide/alkyne click chemistry
A facile synthetic route for the preparation of dicationic ethylene glycol based-ionic liquids (ILs) via the azide/alkyne click reaction is presented. The copper(I) catalyzed, microwave-assisted azide/alkyne click reaction between diazido-ethylene glycols and the corresponding alkyne containing IL-head group enables a simple preparation of different sets of poly(ethylene glycol)-based ILs. Beside tetra- and hexa(ethylene glycol)-based ILs, also oligomeric (Mn = 400 g/mol) and polymeric ILs (Mn up to 1550 g/mol) could be prepared in good yield and with full conversion of the ionic head group. The prepared ILs were extensively characterized via NMR spectroscopy and ESI-time-of-flight (TOF) mass spectroscopy, revealing the formation of multiply charged ions in the negative mode. Thermal stability proved to be exceptionally high (up to 300 degrees C) together with low glass-transition temperatures. (C) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013