Designing Ionic Liquid-Derived Polymer Composites from Poly(Ionic Liquid)–Ionene Semi-interpenetrating Networks

While the solvating power of ionic liquids (ILs) for a variety of solute types including polymers is well-known, the use of ILs as solvents for ionenes—charged polymers with cationic moieties within the backbone—has only recently begun to be explored. IL–ionene combinations offer vast possibilities to make iongels and perhaps even use ILs to exert control over ionene organization (i.e., coil or rod). If the IL solvent is also polymerizable, then poly(IL)–ionene semi-interpenetrating networks (semi-IPNs) can be achieved. This study reports, for the first time, examples of poly(IL)–ionene semi-IPNs formed by dissolving an ionene in a vinyl-functionalized imidazolium IL followed by subsequent photopolymerization of the IL around the ionene. The resultant poly(IL)–ionene semi-IPNs exhibit greater elasticity and ionic conductivity than the neat poly(IL). Thus, the addition of 10–20 wt % ionene can lead to significant changes in the properties of poly(IL) materials. Given the limitless possibilities for IL and ionene structures, this unique type of ionic composite presents vast opportunities for material design.