(754i) Micellization of Poloxamer Block Copolymers in Ionic Liquids and Their Mixtures with Water

Ionic liquids (ILs), organic salts that are fluid at ambient conditions, are a novel class of compounds with a combinatorially great chemical diversity and unique properties. The very low volatility and high thermal and chemical stability that many ILs exhibit render them promising as solvents. We are interested in the self-assembly properties in ionic liquids of block polymers, in particular those of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) family, commercially available as Pluronics or Poloxamers. We consider here solutions of a relatively hydrophobic PEO-PPO-PEO block copolymer (Pluronic P123) in the ionic liquid ethylammonium nitrate (EAN) and its mixtures with water. We report on the onset of micelle formation (cmc) and on micellization thermodynamics, and discuss the underlying interactions between P123 and EAN, P123 and water, and EAN and water. We compare the effects on aqueous Pluronic P123 micellization of ethylammonium nitrate to those of ammonium nitrate. We further compare the effects of the protic IL EAN to those of imidazolium ILs.