Highly stretchable electrodes based on double network structure for dielectric elastomers actuators and generators

Dielectric elastomer (DE) is one of electro-active polymer (EAP), which has low elastic stiffness, high dielectric constants and high strain energy levels. Recently a lot of researches have been carried out for the actuator and generator applications based on DE. The DE polymers used for such applications usually undergoes repetitive tensile strain. Generally, carbon grease is the well known electrode materials for such application. But carbon or silver grease-type electrodes are not allowed for long-time use because of cracks occurrence after some period under repeated extension. To avoid such crack formation, the electrodes should be designed to be flexible and stretchable. We propose a stretchable electrode by employing wrinkles on the surfaces. Acrylic rubber (AR) sheet was first swollen in silicone rubber (SR) solution with conducting fillers such as carbon nanotubes (CNT) to make the SR and CNTs to be diffused to the surface of AR sheet. After drying, the sheet was stretched to a desired length and crosslinked the SR network. Then the sheet was relaxed then wrinkles were formed on the surface of the AR sheet. The presence of wrinkles was confirmed by SEM and the electric resistance was measured as a function of tensile strain.