Electrothermal-responsive flexible actuator of paper-based MWCNTs/PEDOT:PSS composites and PLA using 4D printing

Abstract Based on the traditional additive manufacturing, four-dimensional (4D) printing technology combines structure and shape memory effect (SME), which provides an effective way for the evolution of three-dimensional (3D) printing structure in shape, property and function. However, most of the current researches focus on the influence of printing process parameters on the mechanical properties of parts, and the actuation performance of hybrid conductive polymers is poor. Herein, a method combining 3D printing and coating is proposed to fabricate the electrothermal-responsive three-layer structural flexible actuator of paper-based Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) and multi-walled carbon nanotubes (MWCNTs) composites and polylactic acid (PLA) using 4D printing. The paper-based flexible layer is used as the support layer, the PLA layer made by 3D printing on one side of the paper-based layer is used as the active deformation layer, the MWCNTs/PEDOT:PSS conductive layer coated on the other side of the paper-based layer is used as the electrical actuation layer. The 4D deformation principle of the electrothermal-responsive flexible actuator was analyzed. The influence of printing parameters on the deformation angle of the flexible actuator was analyzed by orthogonal experiment. The experimental results show that the optimal printing parameters are the printing thickness of 0.1 mm, the printing speed of 50 mm s −1 , the filling rate of 58%, and the substrate temperature of 60 °C. Under the optimal parameters, the fabricated three-layer structural flexible actuator of paper-based PEDOT:PSS/MWCNTs composites and PLA achieves a larger bending angle of 472.54° under a driving voltage of 25 V. Therefore, the prepared flexible actuator has excellent actuation performance. Moreover, the fabricated flexible actuators are applied in the fields of the flexible hand and the flexible manipulator, which demonstrates the great potential of the flexible actuator in the fields of human-computer interaction and flexible robot.