cm9b03670_si_004.mp4 (1.09 MB)
Simultaneous Surface Covalent Bonding and Radical Polymerization for Constructing Robust Soft Actuators with Fast Underwater Response
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posted on 2019-11-07, 20:34 authored by Huijuan Lin, Shuanhong Ma, Bo Yu, Xiaowei Pei, Meirong Cai, Zijian Zheng, Feng Zhou, Weimin LiuAlthough extensive
attention is focused on layered hydrogel actuators,
realizing both fast bending and recovery in short time along with
multidirectional space deformation is still a challenge. Herein, novel
thermoresponsive hydrogel/elastomer composite actuators are fabricated
by simultaneous growth and interface bonding of an ultrathin poly(N-isopropylacrylamide) (PNIPAAm)/PAA hydrogel layer on the
poly(dimethylsiloxane) (PDMS) sheet using the surface catalytically
initiated radical polymerization method. The growing hydrogel layer
shows a strong interface combination force of ∼142 N m–1 against the PDMS sheet. The composite actuators show
fast, reversible, and diverse responsive bending/recovery behavior
in response to temperature change of the water bath. In a typical
case, the actuator demonstrates both fast responsive bending from
0 to 500° (50 °C underwater) and fast deformation recovery
from 500 to 0° (20 °C underwater) in less than 7 s. Such
a fast responsive behavior can be attributed to the ultrathin thickness
(μm) of the hydrogel layer. Based on this advantage, our actuators
can generate directional movement as a soft robot on the ratchet surface
upon applying alternating temperature field. Furthermore, novel asymmetric
actuators can be easily developed by the selective growth of the hydrogel
layer onto each side of the structured PDMS sheet, which can achieve
a bidirectional bending and recovery behavior along with a spatial
transportation of cargos.