Flexoelectricity in Flexoionic Polymer Electrolyte Membranes: Effect of Thiosiloxane Modification on Poly(ethylene glycol) Diacrylate and Ionic Liquid Electrolyte Composites

Camilo Rendon Piedrahita; Peijing Yue; Jinwei Cao; Heather Lee; Chathuranga Prageeth Rajapaksha; Chenrun Feng; Antal Jákli; Thein Kyu

doi:10.1021/acsami.0c02328

Flexoelectricity in Flexoionic Polymer Electrolyte Membranes: Effect of Thiosiloxane Modification on Poly(ethylene glycol) Diacrylate and Ionic Liquid Electrolyte Composites

ACS Appl Mater Interfaces. 2020 Apr 8;12(14):16978-16986. doi: 10.1021/acsami.0c02328. Epub 2020 Mar 26.

Authors

Camilo Rendon Piedrahita¹, Peijing Yue¹, Jinwei Cao¹, Heather Lee^{1

2}, Chathuranga Prageeth Rajapaksha, Chenrun Feng, Antal Jákli, Thein Kyu¹

Affiliations

¹ Department of Polymer Engineering, University of Akron, Akron, Ohio 44325, United States.
² Physics Department, Washington University in St. Louis, St. Louis, Missouri 63130, United States.

PMID: 32212666
DOI: 10.1021/acsami.0c02328

Abstract

The present article entails the generation of flexoelectricity during cantilever bending of a solid polymer electrolyte membrane (PEM), composed of poly(ethylene glycol) diacrylate (PEGDA) precursor and ionic liquid (hexylmethylimidazolium hexafluorophosphate). The effects of thiosiloxane modification of PEGDA precursor on glass transition, ionic conductivity, and flexoelectric performance have been explored as a function of PEM composition. The glass transition temperature (T_g) of the PEM declines with increasing thiosiloxane amount in the PEGDA co-network, while the ionic conductivity improves. The PEM/compliant carbonaceous electrodes assemblies were assembled to determine the flexoelectric coefficients by monitoring electrical voltage/current outputs for various PEM compositions under the intermittent square-wave and dynamic oscillatory sine-wave deformation modes. Of particular interest is that the room temperature flexoelectric coefficient exhibits strong frequency dependence in the vicinity of 0.01-10 Hz, suggesting that ion polarization and ion transport through the ion-dipole complexed networks can still be affected by the mobile side chain branches even in the elastic regime of the covalently bonded PEGDA network. The in-depth understanding of the effect of thiosiloxane side chain on flexoelectricity generation is anticipated to have impact on the development of mechanoelectrical energy conversion devices for energy harvesting applications from natural and dynamical environment.

Keywords: flexoelectric coefficient; flexoelectricity; glass transition (Tg); ionic conductivity; ionic liquid; poly(ethylene glycol) diacrylate (PEGDA); solid polymer electrolyte membrane (PEM); thiosiloxane.