Multifunctional Hydrogel Based on Synergistic Hydrophobic and Multivalent Hydrogen-Bond Interactions

Abstract

Developing soft materials that integrate high mechanical performance, self-healing, adhesion, and stimulus-responsive functions remains challenging due to the trade-off between dynamic reversibility and mechanical resilience. Here, we report a P(AA-MA-OA-FHMA) hydrogel fabricated via one-pot free-radical copolymerization, in which hydrophobic association and multivalent hydrogen bonding are synergistically integrated as dual dynamic cross-linking mechanisms. The salicylaldehyde-derived monomer (FHMA) serves as a triple-functional building block, providing hydrophobic domains, hydrogen bonding sites, and metal-chelating coordination sites. The hydrogel exhibits an ultrahigh fracture strain exceeding 4000%, a tensile strength of 278 kPa, self-healing efficiency of ∼75% at room temperature, and an adhesion strength of 40 kPa on porcine skin. The FHMA moieties enable multicolor fluorescence (blue with Zn²⁺, green with Al³⁺, and orange with hydrazine hydrate), while Al³⁺ coordination imparts selective antibacterial activity against Escherichia coli with nearly 100% killing efficiency. The ionic conductivity further enables strain-responsive sensing for both joint movements and subtle physiological activities. This work provides a simple platform for constructing multifunctional hydrogels with potential applications in wearable electronics, biointerfaces, and wound dressing.