Near‐Infrared Light‐Driven, Highly Efficient Bilayer Actuators Based on Polydopamine‐Modified Reduced Graphene Oxide

Abstract

Near‐infrared (NIR) light‐driven bilayer actuators capable of fast, highly efficient, and reversible bending/unbending motions toward periodic NIR light irradiation are fabricated by exploiting the photothermal conversion and humidity‐sensitive properties of polydopamine‐modified reduced graphene oxide (PDA‐RGO). The bilayer actuator comprises a PDA‐RGO layer prepared by a filtration method, and this layer is subsequently spin‐coated with a layer of UV‐cured Norland Optical Adhesive (NOA)‐63. Given the hydrophilicity of PDA, the PDA‐RGO layer can absorb water to swell and lose water to shrink. The intrinsic NIR absorbance of RGO sheets convertes NIR light into thermal energy, which transfers the humidity‐responsive PDA‐RGO layer to be NIR light‐responsive. Considering that the shape of the NOA‐63 layer remains unchanged under NIR light, periodic NIR light irradiation leads to asymmetric shrinkage/expansion of the bilayer, which enables fast and reversible bending/unbending motions of the bilayer actuator. We demonstrate that compared with a poly(ethylenimine)‐modified graphene oxide layer, the PDA‐RGO layer is unique in fabricating highly efficient bilayer actuators. A NIR light‐driven walking device capable of performing quick worm‐like motion on a ratchet substrate is built by connecting two polyethylene terephthalate plates as claws on opposite ends of the PDA‐RGO/NOA‐63 bilayer actuator.

Super-Deformed Asymmetric Actuators: Balance of Photothermal and Humidity Response Effects through Structural Regulation

“…This is due to the formation of hydrogen bonds between sodium alginate and polyurethane as analyzed in the infrared spectrum above, so the layers were closely connected. Compared with the asymmetric structure actuator materials reported in other studies (Figure h), ,,− the film actuators produced in this experiment had excellent combined response effect of infrared light and humidity, and achieved super-large bending deformation. Moreover, the thickness of the SA/GO layer had regulated the response angle, and the application performance was superior to the previously reported photothermal and humidity dual-response actuators.…”

Multiresponsive Bidirectional Bending Actuators Fabricated by a Pencil‐on‐Paper Method

“…The maximum bending curvature of BOPP/graphite/paper is as large as 2.6 cm −1 , which is larger than previous reported BOPP‐based thermal actuators and carbon‐based thermal actuators . Several graphene‐based actuators that are sensitive to humidity and light have been reported recently . However, they cannot demonstrate bidirectional bending.…”

A Graphene‐Based Bimorph Structure for Design of High Performance Photoactuators

“…3.6 s to deform from 84° to 563°, and about 7 s to recover back. This rolled bimorph photoactuator outperforms many of previously reported photoactuators in terms of the amplitude of deformation and response rate . It is also found that the actuator quickly reach the maximum deformation angle after turning on the light, and then keep it until the light is off.…”