1Eastern Michigan University & Strider Research Corporation, Ypsilanti, United States
The number of reported supramolecular organic salts and supramolecular organic-inorganic hybrid salts exhibiting room temperature and near room temperature liquidity is steadily increasing, and such supramolecular ionic liquids (SIL) may be characterized according to their effective dimensionality depicted in Figure 1. In this context, conventional ionic liquids are 0D objects, and SIL are polymeric ionic liquids of varying dimensionality. They may also be characterized according to their predominant macromolecular or biomolecular structures, including nucleic acids, nanotubes, graphitic quantum dots, polymerized ionic liquids, proteins, polyurethanes, and so forth.
Multiple types of SIL are described in detail along with several applications. We exemplify development of hybrid inorganic core-organic shell SIL based on organosiloxane autocondensation to produce solvent-free nanofluids that are viscous liquid polymerized ionic liquids. These materials function as exotic cross-linking agents, sealants, UV protective clearcoats, and ameliorate embrittlement in nanocomposites. We also show that a core-free example illustrates polydispersity frustration of crystallization while exhibiting glass and freezing transitions that are lambda transitions. Linear and cross-linked radical chain-polymerization of conventional IL monomers that are liquids compose another important class of SIL that offers similar advantages to those provided by molecular IL. These SIL promise to overcome leaching limitations in liquid supported membranes and polyelectrolyte membranes in batteries and fuel cells. Lastly, we illustrate that polyurethane and polyester condensation-polymerization incorporating IL monomers yield SIL that are viscous liquids. The IL monomer components enable these SIL to auto-disperse in water, thereby producing polyurethane dispersions and polyester dispersions. Such SIL also function as stabilizers and binders, and we illustrate their stimuli-responsiveness in dispersion and in coatings.