A Solid State Zwitterionic Plastic Crystal With High Static Dielectric Constant.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41546164.
- Also identified by DOI 10.1002/adma.202517774 and PMC identifier 12921328.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Solid materials with a high dielectric constant have a wide range of applications in the energy storage field. In this research, an imidazolium-based zwitterion is designed, synthesized, and confirmed to have a plastic crystal phase based on the following experimental and computational evidence: (i) the presence of long-range order with weak intermolecular forces and competing attractive-repulsive interactions along different crystallographic directions; (ii) the observation of more than one endotherm on heating including a solid-solid phase transition at T<sub>s-s</sub> = -26 °C and melting of the plastic crystal at T<sub>m</sub> = 72°C; (iii) a low entropy of fusion at melting (2.1 JK<sup>-1</sup>mol<sup>-1</sup>); (iv) a strongly anisotropic morphology; (v) relatively fast dynamics originating from short-range degrees of freedom. Furthermore, it exhibits a very high dielectric constant in the plastic crystal solid state (147 at -10°C and 103 at 70°C) due to the rotational degrees of freedom of plastic crystals that arise from weak net intermolecular interactions of zwitterions due to only having two carbons between the anion and cation. This material conveniently remains in the plastic crystal phase within 50 K of ambient temperature. This discovery opens new opportunities in the search for solid-state high dielectric constant materials.