Mechanisms of Dielectric and Electromechanical Enhancements in PVDF-Based Tetrapolymers

We describe simulations of electric-field-induced structural transformations in P(VDF-TrFE) polymers with small admixtures of chlorofluoroethylene (CFE) and fluorinated alkyne (FA) monomers. At low concentrations, FA monomers provide pivot points that facilitate transformations of P(VDF-TrFE) chain segments between the non-polar helix and polar all-trans phases. The chain segmentation enables structural transformations from the non-polar to the polar phase at modest applied electric fields due to the lowering of the electric enthalpy in the field. The transformations significantly increase the dielectric constant and lead to record electromechanical properties, as recently demonstrated experimentally [1]. We also elucidate the phase transformation energetics and calculate the average induced strain in the segments and the average electroactuation strain.

1. X. Chen, H. Qin, X. Qian, W. Zhu, B. Li, B. Zhang, W. Lu, R. Li, S. Zhang, L. Zhu, F. D. Dos Santos, J. Bernholc, and Q. M. Zhang, Science 375, 1418 (2022).