Polymeric Ionic Liquids with Micelle-like Topologies and Functions

Abstract

Micelles and micelle-forming amphiphilic polymers play an important role in nature and in everyday life. Today, the bio-inspired development of synthetic polymers with micelle-like molecular architectures goes well beyond the scope of biological micellar systems. Particularly, amphiphilic core–shell polymeric electrolytes, equivalent to unimolecular micelles, are much more robust and less sensitive to shear-, temperature-, and pH-induced disintegration. Among amphiphilic materials, polymeric ionic liquids (PILs) are attracting great attention, since they combine the features of low-molecular-weight ionic liquids (ILs) with the properties and facile processing typical of polymers. Hence, the precise incorporation of IL moieties into macromolecular core–shell and onion-like architectures represents an attractive route to nanostructured PILs exhibiting functions typical for micelles. This chapter highlights the progress made in bio-inspired molecular systems engineering by designing micelle-like PILs comprising dendritic and hyperbranched polymers as cores and IL-moieties with variable alkyl substitution in their periphery. Special focus is placed upon the design of hyperbranched PILs with onion-like topologies, enabling tailoring specific functions. The wide applications of compartmentalized PIL systems span from the synthesis of particles and dispersions to catalysis and smart materials that respond with property changes to external stimuli.

Thermoresponsive Polymer Ionic Liquids and Nanostructured Hydrogels Based upon Amphiphilic Polyisobutylene-b-poly(2-ethyl-2-oxazoline) Diblock Copolymers

“…Due to the unique physicochemical properties of ionic liquids (ILs), it is very attractive to incorporate IL moieties into polymers and a plethora of polymeric ILs with various chemical structures and topologies has been prepared. − The development of thermoresponsive IL-based polyelectrolytes, as reviewed by Kohno et al, represents an intriguing field of research. There are some examples of poly­(2-oxazoline)­s bearing IL cation end groups such as trialkylammonium , or pyridinium. , Moreover, ionic poly­(2-phenyl-2-oxazoline) macromonomers and corresponding comblike polyelectrolytes have been prepared .…”

Programmable Thermoresponsive Micelle-Inspired Polymer Ionic Liquids as Molecular Shuttles for Anionic Payloads

“…These micelle-inspired polyelectrolytes function as highly effective molecular transporters in two-phase systems and enable phase transfer of molecules and nanomaterials from water into immiscible non-polar organic solvents. 23 However, they only allow for the unidirectional and irreversible transport and do not enable shuttling of payloads back and forth between two phases. The programmable thermal switching of the transport between two phases is highly desirable for many applications including catalyst recycling.…”

“…They are composed of a hyperbranched poly­(3-ethyl-3-hydroxymethyloxetane) (PEHO) core, an inner ionic shell of covalently attached imidazolium cations with tosylate counter anions, and a nonpolar outer shell of alkyl chains. These micelle-inspired polyelectrolytes function as highly effective molecular transporters in two-phase systems and enable phase transfer of molecules and nanomaterials from water into immiscible nonpolar organic solvents . However, they only allow for the unidirectional and irreversible transport and do not enable shuttling of payloads back and forth between two phases.…”