Grasinger Matthew, Majidi Carmel, Dayal Kaushik
Pittsburgh Quantum Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Department of Civil and Environmental Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA.
Phys Rev E. 2021 Apr;103(4-1):042504. doi: 10.1103/PhysRevE.103.042504.
Statistical mechanics is an important tool for understanding polymer electroelasticity because the elasticity of polymers is primarily due to entropy. However, a common approach for the statistical mechanics of polymer chains, the Gaussian chain approximation, misses key physics. By considering the nonlinearities of the problem, we show a strong coupling between the deformation of a polymer chain and its dielectric response, that is, its net dipole. When chains with this coupling are cross linked in an elastomer network and an electric field is applied, the field breaks the symmetry of the elastomer's elastic properties and, combined with electrostatic torque and incompressibility, leads to intrinsic electrostriction. Conversely, deformation can break the symmetry of the dielectric response, leading to volumetric torque and asymmetric actuation. Both phenomena have important implications for designing high-efficiency soft actuators and soft electroactive materials, and the presence of mechanisms for volumetric torque, in particular, can be used to develop higher degree of freedom actuators and to achieve bioinspired locomotion.
统计力学是理解聚合物电弹性的重要工具，因为聚合物的弹性主要源于熵。然而，聚合物链统计力学的一种常用方法，即高斯链近似，忽略了关键的物理特性。通过考虑该问题的非线性，我们展示了聚合物链的变形与其介电响应（即其净偶极矩）之间的强耦合。当具有这种耦合的链在弹性体网络中交联并施加电场时，电场会破坏弹性体弹性特性的对称性，并与静电扭矩和不可压缩性相结合，导致固有电致伸缩。相反，变形会破坏介电响应的对称性，导致体积扭矩和不对称驱动。这两种现象对于设计高效软致动器和软电活性材料都具有重要意义，特别是体积扭矩机制的存在可用于开发更高自由度的致动器并实现仿生运动。
