Pervasive mechanical impact is growing requirement for advanced high-performance protective materials, while the electromagnetic interference (EMI) confers severe risk to human health and equipment operation. Bioinspired structural composites achieving outstanding safeguards against a single threat have been developed, whereas the synergistic implementation of impact/EMI coupling protection remains a challenge. This work proposes the concept of nacre-mimetic hierarchical composite duplicating the "brick-and-mortar" arrangement, which consists of freeze-drying constructed chitosan/MXene lamellar architecture skeleton embedded in a shear stiffening polyborosiloxane matrix. The resulting composite effectively attenuates the impact force of 85.9%−92.8% with extraordinary energy dissipation capacity, in the coordinative manner of strain-rate enhancement, structural densification, lamella dislocation and crack propagation. Attributed to the alternate laminated structure promoting the reflection loss of electromagnetic waves, it demonstrates an ultraefficient EMI shielding effectiveness of 47.2−71.8 dB within extremely low MXene loadings of 1.1−1.3 wt %. Furthermore, it serves favorably in impact monitoring and wireless alarm systems and accomplishes performance optimization through the combination of multiple biomimetic strategies. In conclusion, this function-integrated structural composite is shown to be a competitive candidate for sophisticated environments by resisting impact damage and EMI hazards.
A novel
shock-resistant, self-generating triboelectric nanogenerator
(SS-TENG) with high-speed impact energy-harvesting and safeguarding
properties was developed by assembling Kevlar fiber and conductive
shear-stiffening gel. The SS-TENG with energy-harvesting property
generated a maximum power density of 5.3 mW/m2 with a voltage
of 13.1 V under oscillator compression and could light up light-emitting
diode arrays. Owing to the energy absorption effect, the as-designed
SS-TENG could dissipate impact forces from 2880 to 1460 N, showing
anti-impact performance under the drop hammer impact. It also sensed
the loading forces by outputting 36.4 V. Functionalized as a self-powered
sensor, SS-TENG monitored various human movements and provided protection
from hammer impact. Interestingly, a wearable sole array with high
sensitivity and a fast response could distinguish toe in/out motions.
More importantly, this functional SS-TENG presented excellent anti-impact
behavior, which dissipated 94% of kinetic energy under bullet-shooting
excitation. It also gathered high speed ballistic energy, which outputted
a maximum power density of 3 mW/m2. To this end, this SS-TENG
with a protection effect and the ability to harvest various impact
energy showed promising applications in new power sources, intelligent
wearable systems, and safeguard areas.
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