Silicone rubber-based self-healing flexible sensors with quadruple hydrogen bonding

With growing interest, people are increasingly utilizing sensing materials in their daily routines to monitor their physical movements and health. However, the material may be compromised by internal factors and extended exposure to the external environment, leading to signal destabilization and material degradation. A self-healing flexible sensing material based on quadruple hydrogen bonding was synthesized for the purpose of this research. The UPy-NCO compound, capable of forming quadruple hydrogen bonds between molecules, was synthesized by combining 2-amino-4-hydroxy-6-methylpyrimidine (UPy) and 1,6-hexanediyl diisocyanate (HDI), and then grafted onto nanoscale SiO₂ filler and silicone rubber substrate 107 (PDMS) simultaneously. Multi-walled carbon nanotubes (MWCNTs) were treated with a silane coupling agent KH560 to enhance their conductivity, and mixed with tetrahydrofuran (THF) to create mPDMS/mMWCNTs sandwich-type composite material for sensing applications. It exhibited an elongation at break of up to 130% and a tensile strength of 0.48 MPa, surpassing PDMS by more than 300%. The self-repairing efficiency of the composites was 64% at room temperature and increased to 83% at 60°C after 6 h. Additionally, these materials demonstrated a response speed of 141 ms, comparable to that of human skin (100 ms), indicating promising applications across various fields.