Thermoresponsive
hydrogel-based actuators are highly important for fundamental research
and industrial applications, while the preparation of temperature-driven
bilayer hydrogel actuators with rapid response to bend and recover
properties remains a challenge. To date, most temperature-driven bilayer
hydrogel actuators are based on polymers only with a lower critical
solution temperature (LCST) or with an upper critical solution temperature
(UCST), which need more time to bend and recover just in a small range
of bending angle. Herein, we propose a new strategy to design and
synthesize a fully temperature-driven bilayer hydrogel actuator, which
consists of a poly(N-acryloyl glycinamide) (NAGA)
layer with a UCST-type volume phase change and a poly(N-isopropyl acrylamide) (NIPAM)-Laponite nanocomposite layer with
an LCST-type volume phase change. Due to the complementary UCST and
LCST behavior of the two selected polymers, both layers have opposite
thermoresponsive swelling and shrinkage properties at low and high
temperatures; this imbues the hydrogel actuator with rapid thermoresponsive
bending and recovery ability, as well as a large bending angle. In
addition, the incorporation of Laponite nanosheets in PNIPAM layer
not only improves the mechanical property of actuators but also provides
the excellent bonding ability of the two-layer interface, which prevents
delamination caused by excessive local stress on the interface during
the bending process. Thanks to high-performance behavior, the actuator
can act as an effective and sensitive actuator, such as a gripper
to capture, transport, and release an object, or as an electrical
circuit switch to turn on and off a light-emitting diode (LED). Overall,
such hydrogel actuator may provide new insights for the design and
fabrication of artificial intelligence materials.
The conductive materials with predominant mechanical properties and high sensitivity have various promising applications, such as in electric skins, soft robotics, and wearable sensors. High-performance, flexible strain sensors based on...
A multifunctional conductive hydrogel with controllable adhesiveness, high strechability and excellent biocompatibility based on PDAEA, clay, and PNIPAM.
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