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Redox-Active Polymeric Ionic Liquids with Pendant N-Substituted Phenothiazine
Saejin Oh1, Andrei Nikolaev1, Kan Tagami1
1Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States.
ACS Applied Materials & Interfaces
|January 22, 2021
Summary
Researchers developed flexible, electrically conductive polymers for soft electronics. A novel design using polymeric ionic liquid and phenothiazine (PTZ) groups significantly lowered the glass transition temperature (Tg), enabling room-temperature elasticity and charge transport.
Area of Science:
- Materials Science
- Polymer Chemistry
- Organic Electronics
Background:
- Flexible and soft electronics require materials that are both elastic and capable of charge transport.
- Many existing redox-active polymers possess high glass transition temperatures (Tg), limiting their elasticity at room temperature.
- The solid-state behavior of charged polymers without electrolytes remains underexplored.
Purpose of the Study:
- To design and synthesize novel flexible, redox-active polymers with low glass transition temperatures (Tg) for applications in soft electronics.
- To investigate the charge transport properties of these polymers in their doped state.
- To establish a design strategy for achieving elasticity and conductivity in polymers.
Main Methods:
- Synthesis of phenothiazine (PTZ)-based polymers with a flexible ethylene backbone and specific N-substituents.
- Modification of polymer Tg through molecular design, including the use of weakly interacting ionic groups.
- Doping the polymers with trifluoromethanesulfonimide to induce electrical conductivity.
- Characterization using UV-vis-NIR spectroscopy, electron spin resonance (ESR) spectroscopy, and impedance spectroscopy.
Main Results:
- A novel polymeric ionic liquid strategy successfully yielded flexible, redox-active polymers.
- N-substitution of the PTZ pendant group with a specific ethoxyethoxy)ethyl chain significantly lowered the neutral polymer's Tg by ~150 °C.
- Doping resulted in electrically conductive polymers without a substantial increase in Tg.
- Characterization confirmed efficient charge hopping between PTZ groups.
Conclusions:
- The developed molecular design strategy effectively creates flexible, electrically conductive polymers suitable for soft electronics.
- The use of PTZ-based polymeric ionic liquids offers a promising route to tune polymer properties for advanced electronic applications.
- This work demonstrates the potential of designing polymers with low Tg for enhanced performance in flexible electronic devices.
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