All‐in‐One Bioadhesion Via Interfacial Assembly of a Tannic Acid and Phytic Acid‐Based Janus Hydrogel

Integrating disparate functionalities such as robust adhesion, antioxidation, hemostasis, and antibacterial activity into a single polymeric material often leads to performance trade-offs. This work overcomes this through rational interfacial engineering in a Janus hydrogel. A series of poly(vinyl alcohol) (PVA) hydrogels, hybridized with various amine-rich biomacromolecules, is systematically compared. Among them, the PVA/chitosan quaternary ammonium salt (CSQAS) hydrogel is selected as the optimal substrate, owing to its balanced mechanical profile, high toughness, and excellent energy-dissipative capability, key attributes for supporting a functional adhesive interface. On this matrix, a multifunctional adhesive interface is constructed via the stepwise self-assembly of tannic acid (TA) and a PVA/phytic acid (PA) complex. This molecularly engineered Janus interface delivers synergistic performance: strong tissue adhesion (∼9 kPa), efficient radical scavenging (94.6%), a low blood clotting index (24.9%), and broad-spectrum bacterial inhibition (99.99%). This study exemplifies how deliberate interfacial assembly can resolve functionality conflicts, offering a versatile blueprint for designing advanced, multifunctional soft materials. This study exemplifies how deliberate interfacial assembly can resolve functionality conflicts in soft materials, presenting a versatile strategy for designing advanced multifunctional polymeric interfaces with significant potential for demanding biomedical applications.