Flexible conductive composites can be used as wearable strain sensors, which are widely used in the fields of new-generation robotics, electronic skin, and human detection. However, how to make conductive composites that simultaneously possess flexibility, stretchability, self-healing, and sensing capability is challenging research. In this work, we innovatively designed and prepared a silicone polymer conductive composite. MXenes and amino poly(dimethylsiloxane) were modified by small biomolecules via an esterification reaction and a Schiff base reaction, respectively. The modified MXenes are uniformly dispersed, which endows the composite with good electrical conductivity. The reversibility of multiple hydrogen bonds and imine bonds in the composite system makes it have ideal tensile properties and high-efficiency self-healing ability without external stimulation. The conductive composite containing 10 wt % A-MXenes showed an elongation of 81%, and its mechanical strength could reach 1.81 MPa. After repair, the tensile properties and the electrical conductivity could be restored to 98.4 and 97.6%, respectively. In addition, the conductive composite is further evaluated for the value of wearable strain sensors. Even after cut-healed processes, the conductive composite can still accurately detect tiny human movements (including speaking, swallowing, and pressing). This kind of self-healing MXene/PDMS elastomers based on the modification of small biomolecules has great potential as wearable strain sensors. This simple preparation method provides guidance for future multifunctional flexible electronic materials.
The
design and synthesis of conductive hydrogels with
antifreezing,
long-term stable, highly sensitive, self-healing, and reusable is
a critical procedure to enable applications in flexible electronics,
medical monitoring, soft robotics, etc. Herein, a novel zwitterionic
composite hydrogel possessing antifreezing, fast self-healing performance,
water retention, and adhesion was synthesized via a simple one-pot
method. LiCl, as an electrolyte and antifreeze, was promoted to dissociate
under the electrostatic interaction with zwitterions, resulting in
the composite hydrogels with high electrical conductivity (7.95 S/m)
and excellent antifreeze ability (−45.3 °C). Meanwhile,
the composite hydrogels could maintain 97% of the initial water content
after exposed to air (25 °C, 55% RH) for 1 week due to the presence
of salt ions. Moreover, the active groups of zwitterions could form
conformal adhesion between the composite hydrogels and skin, which
was particularly crucial for the stable signal output of the sensor.
The dynamic borate ester bonds, active group of zwitterions, and the
hydrogen bond between different components could achieve rapid self-healing
(2 h, self-healing efficiency to 97%) without any external intervention.
Notably, the developed PBAS-Li (poly(vinyl alcohol) Borax/acrylamide/zwitterionic-LiCl) hydrogel not only succeeded
in sensitively detecting human motions but also could precisely captured
handwritings signals and subtle pulse waves on the neck and wrist.
The above findings demonstrated the great potential of PBAS-Li hydrogels in the field of flexible electronic devices.
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