Fabrication and Property of Electric-induced Self-healing Nanocomposite Hydrogels

The fabrication of conductive hydrogels with electric-induced self-healing capability exhibits great significance to the development of safe and long-life electronic devices, expanding their application in the field of flexible electronics. For this purpose, the conductive, self-healing nanocomposite hydrogel was fabricated via in situ free radical polymerization with modified Au nanoparticles (NPs) as crosslinkers, poly(o-phenylenediamine) (PoPD) nanobelts as conductive additives and N-isopropyl acrylamide as monomer in the presence of initiator and catalyst. Before the polymerization, N, N-bis(acryloyl) cystamine (BACA) with vinyl groups in the molecular structure was introduced on the surface of Au NPs through the interaction of thiolate-Au (RS-Au) bonding. The successful binding behavior between Au NPs and BACA was confirmed by the transmission electron microscopy (TEM) and UV-visible absorption spectroscopy (UV-Vis). The PoPD nanobelts with a length of nearly 100 mu m and a diameter of 200 nm were prepared by mixing HAuCl4 and oPD solution, and further stirring it at room temperature. The conductivity of PoPD nanobelts could be greatly improved through the strategy of chemical doping by introducing Fe3+ into the aqueous solution. For example, the conductivity can be obtained as high as 5.5 S/m when the concentration of Fe3+ employed was 1 mol/L. By combining the obtained hydrogel network with uniform and compact polymer network, the produced hydrogel showed excellent stretchability (larger than 2400%) and mechanical strength (larger than 1.2 MPa). Impressively, motivated by the thermal instability and Joule's first law, the damaged hydrogel exhibited rapid and highly efficient self-healing performance when the external power supply was available, because of the heating power generated by hydrogels at the cracks. For example, by the aid of power supply with the electric current of 0.05 A, the damaged hydrogel could be healed in 15 min with the optimal healing efficiency of nearly 90%. This prominent performance would contribute greatly to the exploration of flexible electric devices with excellent real-time self-heal ability under the working state from functional hydrogels.