Ageing of Silicone-Based Dielectric Elastomers Prepared with Varying Stoichiometric Imbalance: Changes in Network Structure, Mechanical, and Electrical Properties

摘要

Silicone-based dielectric elastomers are promising dielectric electroactive polymers (DEAPs) applicable to various actuator applications. However, the lack of information concerning their long-term performance still limits their industrial use. Here, the time-dependent behavior of silicon-based DEAPs under electromechanical cycling is investigated. A series of thin silicone films prepared with different stoichiometric imbalances are coated with compliant silver nanowire electrodes and then electromechanically cycled under alternating voltage (V-pp = 2 kV, V-DC = 1 kV) over 10(5) cycles. Afterward, changes in cross-linking density, elastic modulus, permittivity, and breakdown behavior are examined. With increasing load cycles, electrically induced cross-linking of the hydrosilane groups occurs, which leads to increased cross-linking density of the material. Concomitantly, increase in elastic modulus and decrease in permittivity are observed, resulting in a significant deterioration of actuation performance. The measured breakdown strength, which is related to an extrinsic breakdown strength based on electromechanical instability, increases too.