Macroscopic Observation of Structure-Property Relationships in Bulk Poly(Ionic Liquid) Materials

Polymerized ionic liquids or  “poly(ILs)” are of interest as conductive materials, gas separation membranes, novel surface coatings and a number of other thin film applications.  However, we have found that poly(ILs) also exhibit unique and tunable behaviors and properties.   Here, we focus on the macromolecular properties of poly(ILs) with various substituents appended to the imidazolium cation.  Photopolymerization was employed to produce uniform material samples, which were then swelled in a variety of different organic solvents.  Remarkably high swelling capacities were observed in certain solvents (e.g. > 200x in DMSO), indicating IL monomers produce long polymer chains that are loosely crosslinked.   The relationships between IL structure, polymerization conditions and swelling solvent will be discussed. Furthermore, we have also observed self-healing and shape-memory properties.