Electro and Light-Active Actuators Based on Reversible Shape-Memory Polymer Composites with Segregated Conductive Networks

Abstract

Reversible shape-memory polymers (RSMPs) show great potential in actuating applications because of its repeatability among many other advantages. Indeed, in many cases, multiresponsive RSMPs are more expected, and the strategy to introduce functional fillers without deteriorating the reversible deformation performance is of great importance. Here, a facile strategy to balance the electro, photothermal performance, and molecular chain mobility is reported. Segregated conductive networks of carbon nanotubes (S-CNTs) are constructed in the poly­(ethylene-co-octene) (POE) matrix at a relatively low filler loading, which renders the composite good electrical, photothermal, and actuating properties. A low percolation threshold of 0.25 vol % is achieved. The electrical conductivity is up to 0.046 S·cm–1 for the POE/S-CNT composites with 2 vol % CNT, and the absorption of light (760 nm) is above 90%. These characteristics guarantee that the actuator can be driven at low voltage (≤36 V) and suitable light intensity (250 mW·cm–2) with a good actuating performance. An electric gripper and a light-active crawling robot demonstrate the potential applications in multiresponsive robots. This work introduces a facile strategy to fabricate multiresponsive RSMPs by designing CNT network structures in polymer composites and holds great potential to enlarge the applications of RSMPs in many areas including artificial muscles and bionic robots.

A Review of Shape Memory Polymers and Composites: Mechanisms, Materials, and Applications

“…Recently, soft robots based on reversible semicrystalline polymers were reported. For instance, Xu and co‐workers [ 198 ] incorporated CNTs in a poly(ethylene‐ co ‐octene) matrix to fabricate a walking robot that could be driven with a low voltage (≤36V) or IR light irradiation. Yang and co‐workers [ 199 ] synthesized cis ‐1,4‐polybutadiene‐PE copolymer and used it to develop a semicrystalline polymer‐based walking robot ( Figure a).…”

Shape-Memory Polymeric Artificial Muscles: Mechanisms, Applications and Challenges

“…The reason for this is that the CNTs have unique structural arrangements of atoms, a high aspect ratio, and excellent mechanical, thermal, and electronic properties. Additionally, CNTs are highly flexible, which gives them remarkable advantages, making them the best reinforcement component in host polymer matrices [ 119 , 124 ].…”

“…By selectively actuating heating wires in each tubular actuator of the gripper, it was able to grasp and lift a vial after twisting its cap without additional external control. Recently, Xu et al [ 124 ] prepared a mechanical gripper made of poly(ethylene-co-octene) (PEO) and segregated conductive networks of carbon nanotubes (S-CNT) ( Figure 13 d). The PEO-CNT composites with segregated structures had a low modulus and high conductivity, as well as a fast response at low voltage.…”

“…Copyright (2019), American Association for the advancement of Science). ( d ) Schematic of the PEO/S-CNT composites used to grasp and release an object with the voltage on (36 dc) and off with a picture of the gripper for grabbing nuts (Reprinted (adapted) with permission from Xu et al [ 124 ]. Copyright (2019) American Chemical Society).…”

Flexible Bio-tensegrity Manipulator with Multi-degree of Freedom and Variable Structure

“…However, the overall size and weight of peripheral device such as compressor unit, on-board electronics, confines the possibility of using these actuators. Sometimes, the term of soft robot also can be especially described a class of robots using some advanced functional materials with intrinsic actuation as the soft-body material, such as shape memory polymer (SMP) [16], shape memory alloy (SMA) [17][18][19], electroactive polymer (EAP) [20,21], and so on, therefore soft robots are featured with physical self-driven characteristics [16,22]. Soft material have great prospects in the small-scale robots because of their inherent advantages, such as lightweight, compliance, high strain with continuum deformation.…”