PolymeriC 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. For these applications it is desirable to create polymers that are both ionically conductive and mechanically durable. This can be achieved through a variety of methods, including chemical and physical crosslinking, as well as through microphase separated block copolymers. The Segalman group has designed new systems that combine ion conductivity with other desirable properties largely by incorporating ionic liquids into polymers with an emphasis on learning about structure–property relationships for the optimization of new nanostructured, ion-conducting membranes.

Current work also focuses on the use of physical cross-links through metal–ligand coordination to decouple polymer ionic conductivity from bulk mechanical properties. Specifically, we are focusing on the ability to conduct multivalent species through the incorporation of novel ligand species. Through AC impedance, pulsed-field-gradient NMR, and rheology, we seek to measure local ion–polymer interactions and determine design principles for the efficient conduction of multivalent ions.

Polymeric ionic liquids

Polymeric 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 conductivities 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. In collaboration through the NSF MRSEC-funded Interdisciplinary Research Group-2 at UCSB (https://www.mrl.ucsb.edu/research/irg-2-polymeric-ionic-liquids), our group is particularly interested in studying the roles of:

1. Incorporating non-ionic or low dielectric groups for improved processability 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 lead to an improved mechanistic understanding of how ions move through these polymeric ionic liquids. The IRG-2 team will further impart functional properties such as photochromism, multivalent ion conductivity, redox activity, magnetism, and reconfigurability through design and exchange of ions.