Fabrication of amphoteric gelatin nanospheres-doped self-healing nanocomposite hydrogels and the application in flexible sensors

The nanomaterials with two distinct properties or components have outstanding advantages in the synthesis of smart hydrogels. In this work, gelatin nanospheres (GNPs) asymmetrically coated with poly(diallyldimethylammonium chloride) (PDDA) and tannic acid (TA) were synthesized by Pickering emulsion template method. The nanocomposite hydrogel with amphoteric gelatin nanospheres (GPTNPs)-doped was successfully prepared, which has excellent mechanical properties (strain = 616%, stress = 2.85 MPa) and self-healing properties (efficiency = 90.9%) under the synergistic effects of hydrogen bonding and metal coordination. The developed GPTNPs/polyacrylic acid (GPTNPs/PAA) hydrogel sensor exhibits high sensitivity (gauge factor (GF) = 3.69), quick response time (96.4 ms) and superior stability. Therefore, the GPTNPs/PAA hydrogels are excellent materials for application in wearable flexible sensors to monitor real-time human motion.