Interfacial Hydrogen-Bond Regulation by Phytic Acid and SiO2 for Constructing Robust Dual-CrossLinked Nanocomposite Hydrogels

Conventional hydrogels generally suffer from insufficient mechanical strength and structural stability due to limited intermolecular interactions. Herein, a phytic acid (PA)/SiO2 synergistic hydrogen-bond network engineering strategy is proposed to fabricate poly(vinyl alcohol) (PVA)/polyacrylamide (PAM)/PA/SiO2 nanocomposite hydrogels. Unlike traditional PVA/PAM hydrogel systems, PA serves as an interfacial hydrogen-bond-mediating agent to couple SiO2 nanofillers with the PVA/PAM polymer network. The phosphate and hydroxyl groups in PA can simultaneously interact with both the PVA/PAM chains and the silanol groups on the SiO2 surface. Additionally, PA enhances the dispersion stability of SiO2, thereby introducing additional nanoscale interaction sites and forming a synergistic hydrogen-bonding network. Fourier transform infrared spectroscopy (FTIR) and complementary characterizations confirm the formation of extensive intermolecular hydrogen-bonding interactions, revealing the structural regulation mechanism of the hydrogel network. Benefiting from the optimized network architecture, the nanocomposite hydrogel exhibits enhanced mechanical strength, fatigue resistance, antibacterial activity, and highly sensitive strain-sensing performance. Furthermore, an intelligent handwriting recognition system is developed by integrating the hydrogel sensor with machine learning algorithms. This work provides an effective strategy for engineering high-performance multifunctional hydrogels for intelligent sensing applications.