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. 2020 May 7;11(1):2252.
doi: 10.1038/s41467-020-15709-8.

Electron tunneling of hierarchically structured silver nanosatellite particles for highly conductive healable nanocomposites

Daewoo Suh #  1   2 , K P Faseela #  3 , Wonjoon Kim  1 , Chanyong Park  1 , Jang Gyun Lim  4 , Sungwon Seo  1 , Moon Ki Kim  1   4 , Hyungpil Moon  1 , Seunghyun Baik  5
Affiliations

Electron tunneling of hierarchically structured silver nanosatellite particles for highly conductive healable nanocomposites

Daewoo Suh et al. Nat Commun. .

Abstract

Healable conductive materials have received considerable attention. However, their practical applications are impeded by low electrical conductivity and irreversible degradation after breaking/healing cycles. Here we report a highly conductive completely reversible electron tunneling-assisted percolation network of silver nanosatellite particles for putty-like moldable and healable nanocomposites. The densely and uniformly distributed silver nanosatellite particles with a bimodal size distribution are generated by the radical and reactive oxygen species-mediated vigorous etching and reduction reaction of silver flakes using tetrahydrofuran peroxide in a silicone rubber matrix. The close work function match between silicone and silver enables electron tunneling between nanosatellite particles, increasing electrical conductivity by ~5 orders of magnitude (1.02×103 Scm-1) without coalescence of fillers. This results in ~100% electrical healing efficiency after 1000 breaking/healing cycles and stability under water immersion and 6-month exposure to ambient air. The highly conductive moldable nanocomposite may find applications in improvising and healing electrical parts.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1. Synthesis of hierarchically structured AgNS particles.
a Oxygen peroxidizes THF into THF peroxide. b 1H NMR spectra of THF and THF peroxide. c Schematic and chemical mechanism of the radical and reactive oxygen species-mediated vigorous etching and reduction reaction of AgFLs into AgNS particles in a SR matrix. Optical images of the pure SR, AgFL-SR (Ag = 44 vol%), and AgNS-AgFL-SR (Ag = 44 vol%, THF peroxide = 15 mL) nanocomposites are also shown. d FTIR spectra of the pure AgFLs, THF-AgFLs, AgNS-AgFLs, and AgNS-AgFL-SR (Ag = 44 vol%, THF peroxide = 15 mL) nanocomposite.
Fig. 2
Fig. 2. Characterization of medium and small AgNS particles.
a, b SEM images of the AgFL-SR (Ag = 44 vol%, THF = 15 mL) and AgNS-AgFL-SR (Ag = 44 vol%, THF peroxide = 15 mL) nanocomposites without heating. c Size distribution of small and medium AgNS particles. The sum of each frequency is 100%. d, e TEM images of small AgNS particles (THF peroxide-treated AgFLs). The polymer was excluded to get clear images. f Work function distribution of pure SR and AgFLs.
Fig. 3
Fig. 3. Electrical transport property of the AgNS-AgFL-SR nanocomposite.
a The electrical conductivity of the AgNS-AgFL-SR nanocomposite as a function of THF peroxide amount in the initial mixture. The error bars represent the standard deviation of the data. The Ag filler fraction was fixed at 44 vol%. Optical images of the nanocomposites are provided in the inset. b, c The electrical conductivity and density of the AgNS-AgFL-SR nanocomposites are compared with those of control specimens as a function of the total Ag filler fraction. The density was measured by the Archimedes method. The amount of THF and THF peroxide was fixed at 15 mL. The electrical conductivity of the graphite-incorporated healable viscoelastic nanocomposite is also compared. The error bars represent the standard deviation of the data. d The normalized resistance of the AgNS-AgFL-SR (Ag = 44 vol%, THF peroxide = 15 mL) nanocomposite as a function of compressive strain. The error bars represent the standard deviation of the data. The resistance was measured in steady state after relaxation at each strain. The inset image shows the measurement setup. e, f The mechanical stress and electrical resistance relaxation of the AgNS-AgFL-SR (Ag = 44 vol%, THF peroxide = 15 mL) nanocomposite after compressive step strain (strain rate = 1% s−1).
Fig. 4
Fig. 4. Healable electrical transport of the AgNS-AgFL-SR nanocomposite.
a, b Optical and SEM images of the AgNS-AgFL-SR (Ag = 44 vol%, THF peroxide = 15 mL) nanocomposite after breaking and healing. Schematics of the healable AgNS network are also provided. c The resistance change of the AgNS-AgFL-SR nanocomposite during a breaking/healing cycle. An optical image at each step is also provided. d The normalized electrical conductivity of the AgNS-AgFL-SR nanocomposite is shown as a function of the breaking/healing cycles. The error bars represent the standard deviation of the data.
Fig. 5
Fig. 5. Electrical network healing mechanism of the AgNS-AgFL-SR nanocomposite.
a Schematic of the healing mechanism. Tunneling-assisted, non-coalesced, hierarchically structured AgNS particle network between AgFLs is shown above. Conventional electrical network construction by metal nanoparticle coalescence is shown below. b DSC analysis of AgNS-AgFLs and AgNFs without the SR matrix. c DSC analysis of AgNS-AgFL-SR (Ag = 44 vol%, THF peroxide = 15 mL) and AgNF-SR (AgNF = 20 vol%) nanocomposites. d SEM images of two different regions of the AgNS-AgFL-SR nanocomposite after the heating process (200 °C, 1 h). e, f SEM images of the uncured pristine AgNF powders and cured AgNF-SR nanocomposite (200 °C, 1 h, AgNF = 20 vol%). A magnified SEM image of a pristine AgNF is provided in the inset. g The electrical conductivity of the AgNS-AgFL-SR and AgNF-SR nanocomposites before and after heating (200 °C, 1 h) and subsequent breaking/healing cycles. h The normalized electrical conductivity of the AgNS-AgFL-SR nanocomposite as a function of water immersion cycles. The error bars represent the standard deviation of the data. An optical image of the water immersion process (1 min for each cycle) and water contact angles on the pure SR and AgNS-AgFL-SR specimens are also provided. The conductivity was measured after removing residual water on the specimen.
Fig. 6
Fig. 6. Mechanical properties and moldability of the AgNS-AgFL-SR nanocomposite.
a Compressive modulus of the healable nanocomposites. The error bars represent the standard deviation of the data. b The finite element analysis of the AgNS-AgFL-SR nanocomposite as a function of the AgNS particle fraction. The total Ag filler fraction was fixed at 44 vol%. A numerical model (AgNS = 3 vol%) is provided in the inset. The experimentally measured compressive modulus of the AgNS-AgFL-SR (Ag = 44 vol%) nanocomposite is designated by a dashed line. c Storage (G’) and loss (G”) moduli of the pure SR, AgFL-SR, and AgNS-AgFL-SR nanocomposites as a function of shear strain frequency (shear strain amplitude = 1%, 25 °C). d The tan δ of the pure SR, AgFL-SR, and AgNS-AgFL-SR (Ag = 44 vol%, THF peroxide = 15 mL) nanocomposites. The dynamic viscosity is provided in the inset. e, f Macroscale and microscale (width: 20 μm, spacing: 20 μm, height: 10 μm) moldability of the AgNS-AgFL-SR nanocomposite. g Light emitting diode circuit employing random-shaped AgNS-AgFL-SR interconnectors. A magnified optical image is provided in the inset.
Fig. 7
Fig. 7. The robot application demonstration of the AgNS-AgFL-SR nanocomposite.
a An exhaust fan was connected to the healable AgNS-AgFL-SR (Ag = 44 vol%, THF peroxide = 15 mL) nanocomposite circuit at 200 °C, removing toxic gas at harsh conditions. b, c The circuit was cut, accumulating the toxic gas and increasing the gas concentration (relative humidity) above the safe level. d The robot healed the AgNS-AgFL-SR circuit. The healed circuit image is provided in the inset. e The fan restarted, removing the toxic gas and decreasing the gas concentration below the safe level.
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References

    1. Kim Y, et al. Stretchable nanoparticle conductors with self-organized conductive pathways. Nature. 2013;500:59–63. doi: 10.1038/nature12401. - DOI - PubMed
    1. Matsuhisa N, et al. Printable elastic conductors by in situ formation of silver nanoparticles from silver flakes. Nat. Mater. 2017;16:834–840. doi: 10.1038/nmat4904. - DOI - PubMed
    1. Choi S, et al. Highly conductive, stretchable and biocompatible Ag–Au core–sheath nanowire composite for wearable and implantable bioelectronics. Nat. Nanotechnol. 2018;13:1048–1056. doi: 10.1038/s41565-018-0226-8. - DOI - PubMed
    1. Son D, et al. An integrated self-healable electronic skin system fabricated via dynamic reconstruction of a nanostructured conducting network. Nat. Nanotechnol. 2018;13:1057–1065. doi: 10.1038/s41565-018-0244-6. - DOI - PubMed
    1. Markvicka EJ, Bartlett MD, Huang X, Majidi C. An autonomously electrically self-healing liquid metal–elastomer composite for robust soft-matter robotics and electronics. Nat. Mater. 2018;17:618–624. doi: 10.1038/s41563-018-0084-7. - DOI - PubMed