GBAP/L-proline assist of self-healing nanocomposite hydrogels and their applications in antifreeze, high-sensitivity flexible sensors

For novel wearable flexible electronics, the design of hydrogels materials with anti-freezing capability is of great significance to meet the mechanical flexibility and smart sensing at cryogenic temperatures. Herein, glycosyl cross-linking boron acid and ammonium salt of phytic acid (PA) (GBAP) was synthesized based on eco-friendly organic materials, which was successfully wrapped on the surface of graphene oxide (GO) to obtain GO@GBAP. L-proline (L-Pro) as an antifreeze zwitterion and GO@GBAP were implanted in polyvinyl alcohol (PVA) and xanthan gum (XG) three-dimensional network structure. PA with antifreeze property was further introduced as a crosslinking agent, the PVA-XG/GO@GBAP/PA/L-Pro (PGPL) composite hydrogels were successfully prepared. While at −20°C, the PGPL hydrogels had remarkable mechanical strength (0.80 MPa), and they revealed the splendid self-healing efficiency (89.2%) after 4 h of healing. The high-sensitivity flexible sensors based on these PGPL hydrogels exhibited a rapid response time (220.0 ms) and electrical conductivity (detection mean 2.1 S/m at −20°C). Even at −20°C for 24 h, it could still respond to various physical and physiological movements such as swallowing and wrist activities. This nanocomposite hydrogels constructed in this work had expanded their application scope in the field of cryogenic sensing.