Abstract
Materials exhibiting high dielectric constants () are critical for energy storage and actuators. A successful approach to increase is to incorporate polar additives (with high ) but controlling the resulting dispersion state is difficult. Here, we show that significant increases are realized by adding zwitterions, which are small molecules with a cation and an anion separated by covalent bonds. The increase in with zwitterion addition is attributed to the large molecular dipole of zwitterions, ranging from 35 to 41 D, as experimentally quantified and confirmed using density functional theory. At elevated zwitterion concentration in an ethylene glycol medium, there is a nonlinear increase of that eventually saturates due to the strong Coulombic interactions between zwitterions. The presented work provides a fundamental molecular understanding of why zwitterions are effective additives in boosting in soft materials.
- Received 29 June 2021
- Accepted 21 October 2021
DOI:https://doi.org/10.1103/PhysRevLett.127.228001
© 2021 American Physical Society
Physics Subject Headings (PhySH)
synopsis
Simple Additives Make Polar Fluids More Polar
Published 24 November 2021
The strong polar nature of bonded molecular pairs called zwitterions boosts the dielectric constants of polar fluids.
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