Tree-like biomimetic metal-organic framework/carbon nanotube to enhance the dielectric response of sulfurized polyurethane

Abstract

In order to meet the urgent demand for efficient, compact, and low-power actuators in leading-edge flexible electronics, such as wearable devices and soft robots, it is crucial to develop dielectric elastomer actuators with high dielectric constants and low dielectric losses. Inspired by the structure of trees in nature, we constructed a CNT/c-MOF filler with a three-dimensional interpenetrating network structure, with carbon nanotube (CNT) as the “trunk” and conducting metal-organic framework Ni₃(HHTP)₂ (abbreviated as c-MOF) as the “leaves”. The above fillers were combined with synthetic sulfurized polyurethane (S-PU) to prepare CNT/c-MOF@S-PU composite films using the solution casting method, and c-MOF@S-PU composite films were fabricated as a control. This dendritic structured filler improves compatibility with S-PU and significantly increases the specific surface area, thereby enhancing the dielectric constant of the composite film. Concurrently, the internal micropores of the filler suppress excessive charge carrier migration, leading to a reduction in dielectric loss. At 100 Hz, the 3.41 vol% CNT/c-MOF@S-PU composite achieves a dielectric constant of 135.7, which is 1.55 times that of c-MOF@S-PU (87.4) and 25.5 times that of pure S-PU (5.32). Simultaneously, its dielectric loss remains low at 0.13. This reveals the composite film is a promising candidate material for actuators.