Sequence isomerization of dielectric elastomers toward high performances in electrostrain, elastic energy storage, and energy harvesting

Abstract

Dielectric elastomers (DEs) have emerged as promising candidates for actuators, capacitors and generators, but they suffer from low dielectric constants and inferior energy densities. In addition, the mechanism remains unclear, which can be elucidated by molecular dynamics simulations. However, the traditional coarse-grained molecular dynamics (CGMD) simulations cannot study the electromechanical coupling effect of DEs due to the lack of coulombic forces, limiting the structural design of DEs toward achieving high performance. In this work, we study the dielectric response of DEs using CGMD simulations with a charged model for the first time. An interesting phenomenon is observed: head-to-head isomer configuration reduces the chain dipole moment but improves the actuated planar area strain (S_p) by 45% and electromechanical energy density by 378%. The mechanism involves the improvement of polarization due to enhanced dipole alignment in network strands under an applied electric field. Additionally, the sequence isomerism significantly accelerates the response rate and reveals a previously unreported scaling law—S_p = a × lg(time) + b. Moreover, sequence isomerism leads to substantial improvements in charge density, discharge density, discharge efficiency, and maximum polarization under high-frequency electric fields, with increases of 66%, 162%, 58%, and 72%, respectively. These performances of isomers are insensitive to electric field frequency and stress due to the quick dielectric response, demonstrating their promising potential in elastic energy storage, which is emerging as a promising approach for next-generation high-performance capacitors. Furthermore, sequence isomerization enhances the electrostatic potential energy by 85% and confers excellent cycling stability, thereby extending the applicability to energy harvesting systems. This work provides a novel strategy for the design of multifunctional DEs and a new method for studying the dielectric response of DEs. In the future, CGMD simulations with charged models can be developed and applied to design novel DEs such as dielectric liquid crystal elastomers and intrinsically elastic ferroelectric materials.