Soft polymer networks that can conduct currents through motion of ionic species hold potential for the development of new classes of materials and devices. Recent work has focused on the interface formed when one material bearing fixed positive (and therefore mobile negative) ions is placed in contact with another bearing fixed negative (and mobile positive) ions. Such interfaces act much like the electronic gates found in modern electronic devices, which allow current to pass in one direction, but not the other. However, interfaces based on soft ion-conducting polymers offer other interesting properties, such as the ability to reversibly stick and release with the application of a small voltage, and the ability to generate currents when mechanically deformed. This project seeks to deepen our understanding of this emerging class of materials, and to thereby open the door to new types of devices built from them. To do so, it will develop a library of ion-conducting polymers and characterize how the behavior of the resulting interfaces depends on the polymer characteristics. It will provide insight into the tendency of these oppositely charged polymers to mix, or not mix, and use this knowledge to engineer systems that spontaneously assemble into junctions with improved performance. The project will provide opportunities for training and mentoring of students and researchers from the high school to post-doctoral levels, and will partner with nearby high schools and several organizations at the University of Colorado Boulder to engage, recruit, and retain a diverse group of participants.

Technical Abstract

Crosslinked networks of polyelectrolytes with low glass transition temperatures formed from ionic liquid monomers, or ‘ionoelastomers’, have recently emerged as a promising class of soft ion conductors. While recent work has shown that heterojunctions between polyanionic and polycationic materials serve as inherently stretchable ionic diodes, enabling the formation of transistors, low-voltage electroadhesives, and electro-mechanical transducers, much remains to be understood about their operation. This project will establish a library of copolymers with varying content of different ionic charge carriers and different backbone chemistries, and characterize how the behavior of the resulting ionoelastomer heterojunctions depends on these characteristics. It will characterize the tendency of poly(ionic liquid) blends and block copolymers to mix, or undergo micro- or macro-phase separation, as a function of these parameters as well. Finally, it will establish routes based on self-assembly and photochemical patterning of ionic species to yield high surface area nano- and micro-scale heterojunctions, offering potentially dramatic improvements in the performance of the resulting devices. .

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Agency
National Science Foundation (NSF)
Institute
Division of Materials Research (DMR)
Type
Standard Grant (Standard)
Application #
2104892
Program Officer
Andrew Lovinger
Project Start
Project End
Budget Start
2021-09-01
Budget End
2024-08-31
Support Year
Fiscal Year
2021
Total Cost
$460,657
Indirect Cost
Name
University of Colorado at Boulder
Department
Type
DUNS #
City
Boulder
State
CO
Country
United States
Zip Code
80303