Self-Healing Flexible Urea-g-MWCNTs/Poly(urethane-sulfide) Nanocomposite for Sealing Electronic Devices

With the development of flexible electronic devices, strict requirements for sealing these electronics were put forward to. Developing flexible sealant for next generation of flexible electronic devices is essential so as to enable a broad range of application. Herein, we demonstrate a facile way to prepared self-healing flexible urea-grafted mult-walled carbon nanotubes/poly(urethane-sulfide) nanocomposite with robust mechanical strength, flexibility and high self-healing efficiency. On the one hand, urea-grafted mult-walled carbon nanotubes (urea-g-MWCNTs) are used as physical cross-linking agent, which will improve the mechanical strength and self-healing property of the urea-g-MWCNTs/poly(urethane-sulfide) (U-MWC-PUS) nanocomposite. On the other hand, urea-g-MWCNTs are used as a photothermal switch, which will absorb near-infrared (NIR) irradiation and convert it into thermal energy for local self-healing. Owing to the [2+1] radical-mediated disulfide exchange reaction and hydrogen bonding interactions in U-MWC-PUS nanocomposite, the covalent polymer networks can rearrange under thermal stimulation, which make the U-MWC-PUS nanocomposite have self-healing property. When the cracked U-MWC-PUS nanocomposite is kept at the proper temperature or treated with NIR irradiation, it can recover more than 90% of the original tensile strength. Furthermore, self-healing flexible U-MWC-PUS nanocomposite exhibits excellent adhesion and sealability even under water. At the same time, the self-healing mechanism of flexible U-MWC-PUS nanocomposite was analyzed. Our study will provide a facile way to fabricate self-healing flexible U-MWC-PUS nanocomposite for sealing electronic devices.