Bioinspired fabrication of self-recovery, adhesive, and flexible conductive hydrogel sensor driven by dynamic borate ester bonds and tannic acid-mediated noncovalent network

Conductive polymer hydrogels have received enormous attention because of their promising applications in healthcare monitoring, soft robots, and wearable electronics. Development of hydrogel sensor with strong me-chanical properties, excellent sensing capabilities, self-healing and adhesive properties is highly desirable and still remains a critical challenge. Herein, we report a borax crosslinked flexible hydrogel based on polyvinyl alcohol (PVA), sodium alginate (SA), and tannic acid (TA) modify barium titanate (BT) nanoparticles (T@BT) via a facile one-pot method. The crosslinking network was formed by dynamic reversible borate ester bond and TA -enabled interactions including hydrogen bonds and coordination bonds, which endowed the hydrogel with excellent self-healing and mechanical properties. Meanwhile, the combination of functional catechol groups in TA with the significantly improved cohesion of the hydrogel enabled the hydrogel to exhibit strong and residue -free adhesion to a variety of inorganic and organic materials. The adhesion strength to wood was up to 67.5 kPa. Furthermore, the addition of the T@BT not only rendered the hydrogel highly conductive (1.91 S/m) and sensitive for sensing, but also synergistically enhanced the toughness (587.1 KJ/m3) of the hydrogel. This work provides new ideas for the preparation of multifunctional conductive hydrogels.

Automated summary

In this study, a borax crosslinked flexible hydrogel based on polyvinyl alcohol, sodium alginate, and tannic acid modified barium titanate nanoparticles was reported. The hydrogel exhibited excellent mechanical properties, sensing capabilities, self-healing, and strong adhesion to various materials. The addition of nanoparticles enhanced the conductivity and toughness of the hydrogel.