Effect of Glycerol on the Self-Assembly of P123 in a Room-Temperature Ionic Liquid [Bmim]PF<sub>6</sub>

Abstract

Phase behavior of ternary systems involving PEO-PPO-PEO block copolymer (Pluronic P123), room-temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate [Bmim]PF6, and glycerol is investigated at 25 °C by using small-angle X-ray scattering (SAXS) techniques. In this ternary system, the structures formed in the binary P123/[Bmim]PF6 system, hexagonal phase (H1) and lamellar phase (Lα), are still obtained. At lower P123/[Bmim]PF6 ratio, the H1 phase can accommodate more than 30 % glycerol. At higher P123/[Bmim]PF6 ratio, the Lα phase only accommodates less than 2 % glycerol and Lα changes to H1 with increasing the glycerol content. Moreover, a phase separation takes place at a higher glycerol content. Solvatophobic interactions between hydrophobic groups of [Bmim]PF6 and P123, coulombic force existing in the polyoxyethylene chain and imidazolium cation, H-bond between P123 and glycerol, accompanying with the force ascribe to the nitrogen of the imidazole ring and the oxygen of alcohol are helpful for the formation of long-range ordered structure.