Block Copolymer Micelle Shuttles between Water and Ionic Liquids.

摘要

The micelle shuttle is an interesting phenomenon recently discovered by our group: a reversible and intact migration of poly(butadiene- b-ethylene oxide) (PB-PEO) block copolymer micelles between water and a hydrophobic ionic liquid upon a simple temperature stimulus. The micelles allow for encapsulation of cargo molecules and the transfer enables control of their partitioning in the biphasic system. This simple round-trip delivery system can be used in delivery, reaction, and separations in synthesis and biphasic catalysis using ionic liquids. This thesis is aimed to systematically study the components, features, mechanism and possible applications of the micelle shuttle.;For study on the components, several block copolymers and ionic liquids were employed to demonstrate the micelle shuttle, indicating the generality of the phenomenon. To control the loading and release of the micelle nanocarriers in the biphasic system, a thermoreversible micellization-transfer-demicellization shuttle was developed using a multiply thermosensitive block copolymer. The micelle shuttle was also demonstrated using micelles with different nanostructures, including spheres, cylinders, and vesicles. In particular, a new class of vesicles with ionic liquid interiors dispersed in water was developed using a vesicle shuttle. Permeability studies reflect the reasonably permeable membrane of the vesicles, which is desirable for potential applications of these responsive and stable vesicles as recyclable nanoreactors.;As for research into the features, reversible and quantitative transfer appeared to be a common characteristic of the micelle shuttle. A strong temperature dependence of the micelle distribution in the biphasic system was observed, which is favorable for controlled delivery using the micelle shuttle. The transfer temperature determining the micelle partitioning in the biphasic system could be effectively tuned by simply using additives in the aqueous phase.;To understand the transfer mechanism, the driving force, thermodynamics and kinetics of the micelle shuttle were investigated in detail utilizing shuttles of PEO homopolymers and dye-loaded PB-PEO micelles. A detailed multiple-step transfer mechanism was then proposed.;To demonstrate possible applications, micelles formed by the commercial and inexpensive Pluronic block copolymer were employed as nanocarriers for delivery and extraction in the biphasic system. The vesicle shuttle was also utilized to transport various dyes in the biphasic system.