Vanillin-mediated green synthesis of polyacrylic acid/chitosan dual-network hydrogels with antibacterial properties and enhanced mechanical performance.

The polyphenol-metal catalytic scheme plays a crucial role in the synthesis of polyacrylic acid (PAA) hydrogels. Herein, vanillin (VA) not only initiates dynamic redox reactions with Fe to accelerate the polymerization of acrylic acid but also forms Schiff-base bonds with chitosan (CS), thereby facilitating the formation of a CS molecular network. Consequently, VA enables rapid, environmentally friendly synthesis of dual-network hydrogels comprising PAA and CS. Experimental results demonstrate that the products obtained using these hydrogels possess good mechanical properties, adhesion properties, self-healing ability, and antibacterial properties. Under the optimal experimental conditions, these hydrogels exhibit a fracture elongation of 810.30 % and a tensile strength of 202.14 kPa. Introducing phytic acid improves the flexibility and adhesiveness (98.3 kPa for porcine skin) of the hydrogel samples. Moreover, these hydrogels exhibit notable antibacterial properties in the inhibition of both Escherichia coli and Staphylococcus aureus. When used as wearable sensors, PAA-CS hydrogels can monitor human movements in real time while achieving high sensitivity and rapid response. This self-catalytic system based on polyphenol-metal redox reactions offers a green and efficient approach for preparing multifunctional hydrogels.