Segregated Conductive Carbon Nanotube/Poly(ethylene-co-vinyl acetate) Composites for Low-Voltage Reversible Actuators

Abstract

Electrically conductive shape-memory polymer composites have attracted great interest for electrical actuators because of their remote controlling capability, whereas plentiful conductive fillers are always required to achieve low-voltage actuation, which would cause degraded processability and also weaken the intrinsic feature of the shape-memory polymer matrix. The realization of low-voltage actuation with preserved actuating performance of shape-memory polymers is significant for practical application but is still challenging. Herein, we develop a novel electrically reversible actuator that can be actuated at only 15 V based on a segregated carbon nanotube (CNT)/poly(ethylene-covinyl acetate) (EVA) composite with CNTs selectively distributed on the interfaces among the polyhedral EVA regions. The segregated CNT networks endow the composite with low-voltage actuating ability, and the intrinsic characteristics of EVA endow the composite with reversible actuation. Moreover, the selectively distributed state can significantly reduce the obstruction effect of CNTs on EVA molecular chain movement during the actuating and recovery process, in comparison to the conventionally distributed state. The resultant segregated CNT/EVA has a higher reversible actuation of 5% than the conventional CNT/EVA composite (2%), even with 10 wt % CNT loading. The structural changes of these two composites were evaluated by wide-angle Xray scattering to explore the mechanism of the actuation superiority for segregated structures. Based on excellent reversible actuation, the segregated CNT/EVA was proven to assemble multifunctional actuators to realize various applications (flipping signs and lifting objects), providing inspiration in electrical actuators and biomimetic application.

Shape-Memory Polymers Based on Carbon Nanotube Composites

“…Overview of processing methods, resistivity of composites, and tension and recovery time of thermoplastic SMP with CNT. CNT Type Content Polymer Processing Resistivity (Ω·cm) Applied Tension (V) Recovery Time (s) T trans (°C) Year Reference MWCNT - EVA Spray coating 1.05 15 - 70 2021 [ 160 ] 10 wt.% Ball milling + compression molding 6.01 × 10 −1 - - - 2022 [ 173 ] 10 wt.% Melt mixing 21.3 30 - 70 fMWCNT 2 wt.% Ultrasound adsorption 46.0 50 30 to deformation 77 2023 [ 174 <...…”