Micromechanism-based electrochemo-mechanical model for double polarization-actuation of PVC gel-based electronic electroactive polymer

The polyvinyl chloride gel (PVCG)-based electroactive polymer exhibits tunable stiffness and achieves large strains with rapid response at moderate drive voltages (200–3000 V), making it suitable for versatile engineering applications. The electric actuation response of PVCG involves a strong micromechanism-characterized coupling between the electrochemical mobility of the plasticizer and the electro-modulus of PVC chain. Specifically, plasticizer polarization-induced electromigration generates polarization stress and osmotic stress, which act as the active driving forces for high actuation strain in PVCG, while polymer skeleton polarization-induced conformational transformation influences the electro-modulus of PVCG, impeding the deformation process. This work formulates an electrochemo-mechanical model to unravel the double polarization-induced actuation mechanism of PVCG under a thermodynamically consistent large deformation frame. First, we solve the polarization and dynamic evolution of a single polymer chain under electric excitation, as well as a single plasticizer molecule. The total free energy function of PVCG is then integrated through statistical mechanics in line with the full-network model. Subsequently, micromechanism-based constitutive relations are simplified following the core principles of the eight-chain model, incorporating effective stretch and electric field through average directions analytically. The finite element implementation is realized and the model is calibrated through a series of tests. Double polarization-induced actuation properties and the memory effect of PVCG under cyclic activation are analyzed. Additionally, a telescopic driver and a self-sensing variable stiffness artificial muscle model are simulated to showcase the wider applicability of our numerical simulation capability. This work provides theoretical understanding and design guidelines for PVCG at macro/micro scales in the actuation field.