Nanoscale Resolution of Anhydrous, Ionic Polymer Diffusion at Electrified Interfaces
The ability of charged polymers to diffuse at an electrode is crucial to the performance of many energy relevant systems. For example, during battery charge-discharge cycles the electrode roughens and recedes. The polymer electrolyte must diffuse rapidly enough to continue wetting the electrode or the battery will fail. The local mobility at an electrode will also determine the time scale of double layer formation, capacitance, and adhesion. Advanced fluorescence experiments on labeled polymers afford the resolution of diffusion with nanoscale precision at controlled distances from the electrode. Insights from this project will enable the design of polymer electrolytes which continuously wet the electrode leading to longer battery lifetimes.
Polymer diffusion experiments parallel to an electrode surface will provide key insights into developing responsive ionic lubricants as well as friction and wear reduction agents. Small molecules ionic liquids have already demonstrated layering phenomena at charged surfaces making them excellent lubricants. Polymers afford an additional level of tunability through viscosity (molecular weight), composition, and architecture.
Ionic polymers also find use in applications which do not require conductivity such as golf ball coatings. Charges in polymers cluster and aggregate which provides a natural toughening mechanism. We are interested in engineering robust ionic coatings which can heal in response to scratches and cracks. Polymer interdiffusion experiments will seek to understand mechanisms of self-diffusion at interfaces to design rapidly self-healing coatings with additional stimulus control.