Experimental investigation and simulations of the microstructure and actuation performance of PVC gels with varying plasticizers

Abstract

Polyvinyl chloride (PVC) gel actuator is an ideal actuator choice for soft robotics, wearable devices, and human–computer interaction because of its excellent performances under electrical stimulation, such as low driving voltage, large deformation, and asymmetric deformation. These excellent performances originate from the enrichment layer in PVC gel formed by the migration of plasticizers and charge transfer. The intermolecular interactions between plasticizers and PVC molecular chains are crucial in plasticizers migration, but the effect of these factors on actuator’s performance is still unclear. In this study, the effects of types of plasticizes with varying molecular volumes on the actuation performance of PVC gel actuators were systematically investigated using experiments and simulations. The network structure of PVC gels typically consists of a primary network formed by physical entanglements and microcrystals and a secondary network constructed by intermolecular interactions between primary network and plasticizers, including hydrogen bonds and van der Waals forces. The experimental and simulation results indicate that intermolecular interactions significantly influence the migration rate of plasticizers within the PVC gel. The PVC gel actuators prepared with large-volume plasticizers containing a benzene ring structure exhibit the strongest intermolecular interactions. When subjected to an applied stimulus voltage of 800 V, the actuator made with benzene-ring-based plasticizers achieves a maximum displacement of only 23%, along with a relatively longer response time compared to the gel incorporating linear plasticizers. These results provide valuable insights into the relationship between the internal structure and actuation performance of PVC gels for their potential applications in robotic devices and medical assistive equipment.