Polymerized ionic liquiids

Ion-transporting materials

Ion-transporting materials are in high demand for a variety of applications, including fuel cell membranes, solar-fuels membranes, battery electrolytes, and transistors to name a few. For these applications it is desirable to create membranes that are both ionically conductive and mechanically durable by doping one phase of a block copolymer with electrolyte salts or selectively introducing a liquid electrolyte such as an ionic liquid into one phase of a block copolymer, where the second phase in each case provides mechanical support. The Segalman group has thoroughly studied the self-assembly of mixtures of block copolymers with ionic liquids. Our work has involved characterizing their ion-conducting properties using techniques such as AC impedance spectroscopy, pulsed-field gradient NMR, and quasi-elastic neutron scattering, with an emphasis on learning about structure-property relationships. Learning about the relationship between structure and conductivity will lead to the optimization of new nanostructured, ion-conducting membranes.

Random and block copolymers synthesized from both ionic liquid and non-ionic liquid based monomers yield surprising changes in the resulting ionic conductivity.

Random and block copolymers synthesized from both ionic liquid and non-ionic liquid based monomers yield surprising changes in the resulting ionic conductivity.

Polymerized ionic liquids

Polymerized ionic liquids (PILs) are an emerging class of ion-conducting polymers based on the familiar chemistries of ionic liquids. These PILs have many of the same advantageous properties such as high conductivies and robust thermal and chemical stability. In contrast to ionic liquids, either the cation or anion is tethered to the polymer backbone in a PIL which minimizes leakage of the charged species into neighboring materials (for example in a thin film transistor). A major advantage of PILs over commercial ion conducting membranes is that they can operate in the absence of water allowing for high temperature operation. Our group is particularly interested in studying the role of (Fig. 1):

  1. Incorporating non-ionic group for improved processibility without negatively impacting the ionic transport properties of the material
  2. Nanostructuring PIL-containing block copolymers, which can lead to dramatically improved ionic transport properties

Understanding these effects will also lead to an improved mechanistic understanding of how ions move through these polymerized ionic liquids.

Click here to access a list of our publications related to polymerized ionic liquids.