Micro-structured porous electrolytes for highly responsive ionic soft actuators

Abstract

Electro-active ionic polymer actuators are an attractive type of soft actuators that bend due to the ion migration in the polymer electrolyte membrane under the electrical field. However, further explorations are required to enhance their performance, which, in turn, demands for strong and flexible polymer electrolytes with continuous conducting phases, facilitating ion movement. Here, we report a facile methodology to generate continuous ion-conducting channels in polymer electrolytes using two-phase evaporation technique. Immersing the corresponding porous poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-co-HFP) membrane into an ionic liquid converted it into an electrolyte membrane with continuous conducting phases. In such electrolyte membrane, while the PVDF-co-HFP skeletal frame provided high mechanical strength and flexibility, the continuous conducting phases facilitates the ion movement. This enhanced actuation performance. The prepared actuator showed 1.5 times higher performance in comparison with those made of conventional PVDF-co-HFP electrolyte membranes. The as-prepared actuator exhibited a large tip displacement of 25 mm at low voltage of 0.5 V and 0.1 Hz, fast rise time of 2.5 seconds without back relaxation, good stability with retrieving of 95% of the original performance after 20,000 actuation cycles. This high performance actuator could potentially be used in future technologies such as soft robotics and healthcare devices.