Influence of ionic liquids on the critical micellization temperature of a tri-block co-polymer in aqueous media

Abstract

To explore the role of additives in controlling the critical micellization temperature (CMT) of a block copolymer in aqueous solution, in the present work, a series of ionic liquids (ILs) containing the same cation, 1-butyl-3-methylimidazolium, bmim+ and commonly used anions such as SCN−, BF4-, I−, Cl−, CH3COO− and HSO4- were chosen for study with a triblock copolymer, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), (PEG–PPG–PEG) in aqueous solution. The present results suggest that the ability of ILs for decreasing the polymer CMT is mainly a result of not only from charge and size of anions of the ILs, but also due to the weak ion–ion pair interactions within IL. The present study provides important information that can be helpful to tune the IL- or temperature-sensitive copolymer CMT and micelle shapes which are crucial for understanding the drug delivery mechanisms.