Combinational Hydrogel and Xerogel Actuators Showing NIR Manipulating Complex Actions

Abstract

On the other hand, hydrogel actuators have been widely studied owing to their versatile stimuli-response actuations and soft characteristic. The actions of capture, crawling, rolling, or lifting have been accomplished with some specified structures under certain stimuli. [18][19][20][21][22][23][24][25] However, if desired action is complicated with many steps, combinational movement of carrying an object to round an obstacle, for example, will be hard to realize by one hydrogel. Our group previously reported a bioinspired hybrid hydrogel actuator by series combination of three trunks of polymer-clay hydrogels to accomplish a comprehensive actuation of "extensiongrasp-retraction." [26] But, the actions actually realized were only the combination of lifting and laying down.In the previous study, we have found that the poly(N,N-dimethylacrylamide) (PDMAA) hydrogel crosslinked by hectorite clay can be reshaped to desired shape by heating and fixed at low temperature. [27] We attributed this to the partial thermoreversibility of the polymer-clay crosslinking in the hydrogel, which appeared to satisfy the above mentioned expectation of simultaneous formation of the permanent and reversible crosslinking in the same network. On the other hand, graphene oxide (GO) has been adopted as a photothermal transforming reagent to endow the thermo-sensitive hydrogel response to the near-infrared (NIR) irradiation. [26,[28][29][30] Based on these results, we present a novel NIR response combinational hydrogel-xerogel actuator consisting of a hydrogel connected to its dried xerogel, and both the parts have the same composition of PDMAA, hectorite clay, and GO. The hydrogel was radically poly merized with monomer N,N-dimethylacrylamide (DMAA) in a hectorite clay LAPONITE XLG suspension containing GO, and referred to as DmGnGO2, where m and n stood for the DMAA in mol/L and XLG in w/v% of water, respectively, and GO2 for 2.0 mg mL −1 of GO. The xerogel was prepared by elongating and fixing the D1G3GO2 hydrogel to a specified length (≈600%), and drying at 80 °C to a constant weight.In this research, we focus on the shape recovery and complex actuation of this PDMAA-clay/GO hydrogel. Figure 1a and Movie M1, Supporting Information show the shape recovery of the D1G3GO2 hydrogel from the temporary shape to the original shape (as in Figure S1a1, Supporting Information) by NIR laser irradiation. The diameter of the sample is decreased Combinational ActuatorsNear-infrared (NIR)-driven shape memory hydrogels are synthesized with a one-pot polymerization of N,N-dimethylacrylamide in the inorganic clay and graphene oxide (GO) suspension. The hydrogel consists of only a physically crosslinked network, which is partially thermoreversible. With the efficient photothermal energy transformation of GO in the hydrogels, the shape recovery from the temporal shape is achieved by NIR irradiation. The optimal shape fixing percentage and recovery rate are found at moderate monomer and crosslinker contents. Meanwhile, the xerogel dried from the hydrogel al...

Soft Actuators Based On Carbon Nanomaterials

“…After pre-programming, the actuator realized a series of actions under NIR drive. [64] Recently, by imitating the autonomous movement of biological organisms, some novel actuators with self-propelling actuation, showing an autonomous, continuous, and regular response to a constant external environmental stimuli, attracted an upsurging interests immediately after they were proposed. [65][66][67] Those actuators usually designed with a built-in negative feedback loop.…”

“…GO. [64] Electricitydriven e-EAP Doping carbon nanomaterials into dielectric polymer or as surface electrodes to increase dielectric constant or electrode conductivity.…”