Block copolymer micelles with lower critical solution temperature (LCST) as novel stimuli-responsive systems in heterogeneous systems based on ionic liquids

A poly(2-nonyl-2-oxazoline-block-2-ethyl-2-oxazoline-block-2-methyl-2-oxazoline) triblock copolymer was used for the prepn. of self-assembled micelles in the hydrophobic ionic liq. 1-butyl-3-methylimidazolium hexafluorophosphate. It was found that the transfer of the micelles formed by this triblock copolymer from the ionic liq. phase to an aq. phase can be reversibly achieved by heating or cooling the system. The findings reported in this contribution reveal the existence of interesting stimuli-responsive block copolymer micellar structures exhibiting thermo-reversible phase transfer characteristics in a bi-phase system. Stimuli-responsive block copolymer micelles prepd. within this kind of heterogeneous systems may find important applications in the encapsulation, transport, and delivery of guest mols. as well as the development of advanced heterogeneous micellar catalytic and novel sepn. processes.