# Fabrication of a High-Performance Bending Actuator Made with a PVC Gel
## 1 Introduction
The PVDF-based bending actuators are widely used and researched, and furthermore they are enhanced via various methods nowadays. However, they need highly stretchable electrodes for achieving a large bending behavior. [PERSON] et al. [21,22] has presented a poly vinyl chloride (PVC) gel, which could solve the above problems, as an electroactive material for bending actuators. PVC gel-based bending actuators work well in air and do not require stretchable electrodes. Another great advantage of PVC gel-based bending actuators is that they are transparent. Even though a bending actuator based on an electroactive PVC gel does not need stretchable electrodes, there are still problems to be solved in that its response time is slow and its bending angle is not large. We inserted 12 related works in the reference section. Previously, we synthesized PVC and dibutyl adipate (DBA) to fabricate an electroactive PVC gel [23,24]. When a voltage was applied to the developed electroactive PVC gel, the plasticizers in the PVC matrix migrated to the anode side with dragging PVC chains, consequently deforming the PVC gel. As soon as the voltage was removed, the PVC gel returned to its original shape due to its elasticity. Thus, we can readily assume that the stiffness of a PVC gel affects the performance of the PVC gel-based bending actuator. If the stiffness of the PVC gel is too great, its deformation becomes small. In contrast, a compliant PVC gel is deformed a great deal by a small voltage. A large amount of plasticizer not only makes the electroactive gel softer, but also increases the number of moving dipoles so that large amounts of plasticizers deform the PVC gel more. In other words, the actuation performance of the PVC gel is strongly related to the amount of plasticizer added. The crystallinity, entanglement and physical crosslinking in PVC resins are affected by their molecular weight [25,26]. Thus, using PVC resins of different molecular weights would change the mechanical properties of PVC gels. PVC is a semicrystalline polymer having a 3-D crosslinking network. As the molecular weight of PVC increases, the crystalline region inside the PVC also increases. For this reason, the higher the molecular weight of the PVC resin used, the greater the area within the PVC that can be plasticized. Furthermore, a PVC with high molecular weight has denser entanglement and more physical crosslinking, so excess plasticizer can be retained in the PVC chain matrix. Previously, we investigated the effect of the molecular weight of the PVC resin on the electroactive performance of plasticized PVC gels [27]. Because a high-molecular-weight PVC can accept more plasticizer, the performance of PVC gels based on high-molecular-weight PVC resin increases. In this paper, we investigated the electrical and mechanical properties of a PVCgel-based actuator in relation to its molecular weight and plasticizer content. Then, we fabricated a high-performance PVC gel-based actuator. The dynamic mechanical property of the proposed actuator was also investigated, and bending performance examined in terms of response time and maximum bending angle.