A 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 are put forward. Developing flexible sealants for next generation flexible electronic devices is essential for enabling a broad range of applications. Herein, we demonstrate a facile way to prepare a self-healing flexible urea-grafted multi-walled carbon nanotube/poly(urethane-sulfide) nanocomposite with robust mechanical strength, flexibility and high self-healing efficiency. On the one hand, urea-grafted multi-walled carbon nanotubes (urea-g-MWCNTs) are used as physical cross-linking agents, which will improve the mechanical strength and self-healing properties of the urea-g-MWCNTs/poly(urethane-sulfide) (U-MWC-PUS) nanocomposite. On the other hand, urea-g-MWCNTs act 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 the U-MWC-PUS nanocomposite, covalent polymer networks can rearrange under thermal stimulation, which endows the U-MWC-PUS nanocomposite with self-healing properties. When the cracked U-MWC-PUS nanocomposite is kept at an appropriate temperature or treated with NIR irradiation, it can recover more than 90% of the original mechanical strength. At the same time, the self-healing mechanism of the flexible U-MWC-PUS nanocomposite was analyzed. Furthermore, the self-healing flexible U-MWC-PUS nanocomposite exhibits excellent adhesion and sealability in water. Our study may provide a facile way to fabricate self-healing flexible U-MWC-PUS nanocomposites for sealing electronic devices.