Ultra-robust bonding between MXene nanosheets and stretchable, self-healable microfibers

摘要

To develop a reliable fibrous device, a strong bond between conducting materials and fibers must be ensured. While the external surface of the film is relatively flat, making it easy to deposit the electrode materials uniformly, the walls of the polymer fibers inside the porous film pose a greater challenge for ensuring a uniform coating and robust bonding with electrode material. Herein, a microfibril-based porous film was prepared by electrospinning polybutadiene-based urethane (PBU), a newly synthesized self-healing polymer, and Ti3C2-based MXene nanosheets were coated thereon to fabricate a pressure sensor whose resistance decreases with pressure. The PBU microfibrils were crosslinked under mild conditions via Diels-Alder (DA) reaction by exploiting low activation energy of the PBU. An exceptionally robust bonding between the PBU and MXene was enabled by subjecting the PBU to a retro-DA and subsequent DA reactions. The temporary increase in surface fluidity of the PBU leaded to a conformal contact between the MXene and fibers without collapse of fibrous structure, resulting in an ultra-robust bond between them. A stretchable and self-healable pressure sensor was implemented by removing unnecessary MXenes by applying ultrasonic energy to the thus-fabricated sample. The fabricated sensor showed a pressure sensitivity of around 27.9/kPa for a wide range of pressure which is the highest level among the reported stretchable self-healing pressure sensors, while maintaining its performance even after 1000 cycles of stretching and pressing. Further, sensors attached around the carotid artery could be used to precisely detect P-, T-, and D-waves arising from blood pressure.