Acrylic acid-based hydrogel with multi-properties endowed by synergistic multifunction of glucurono-dialdehyde xylan...

Conductive hydrogels frequently struggle to balance high conductivity, robust mechanical strength, excellent UV resistance, and antibacterial properties, a limitation that restricts their applications in intelligent wearable sensors. In this work, a comprehensive strategy was developed to fabricate a semi-interpenetrating polymer network (semi-IPN) composite hydrogel. This hydrogel consists of a polyacrylic acid (PAA) network interpenetrated by linear glucurono-dialdehyde xylan (GlcU-DAX) via hydrogen-bonding, reinforced by the synergistic multifunctional effects of GlcU-DAX and silver nanoparticles (AgNPs). Mechanistic investigations demonstrate that GlcU-DAX, which is rich in hydroxyl, carboxyl, and aldehyde groups, plays multiple critical roles in the hydrogel matrix. It not only serves as one of the two main components of the semi-IPN structure, but also acts as a reducing agent for the formation of AgNPs from silver salts. Meanwhile, GlcU-DAX functions as a dispersing stabilizer via electrostatic repulsion originating from its carboxyl groups. This effect helps homogenize acrylic acid (AA) and GlcU-DAX in the precursor solution to form uniform semi-IPNs, while also inhibiting the aggregation of the as-reduced AgNPs and maintaining their small, well-dispersed size within the hydrogel. In addition, GlcU-DAX also acts as a promoter for the polymerization of AA. This innovative application mode fully leverages the structural advantages of xylan. Meanwhile, the reduced AgNPs with small size endow the hydrogel with inherent mechanical reinforcement, UV-blocking capability, and antibacterial activity via Ag⁺ active species. AgNPs also enhance the coordination interactions between GlcU-DAX and PAA, thereby further improving the hydrogel's mechanical and conductive properties. Under optimized conditions, the as-prepared hydrogel exhibits outstanding comprehensive performance, including superior mechanical properties (1235.66% elongation at break, 51.72 kPa tensile stress, 218.07 kPa compressive stress), excellent compression fatigue resistance (95.1% stress retention after 200 cycles at 50% strain), nearly complete UV shielding (transmittance close to zero in both UVA and UVB regions), strong substrate adhesion (up to 36.64 kPa on wood), and high conductivity (0.59 S m^-1). This work not only expands the high-value utilization of xylan and provides a sustainable route for nanomaterial synthesis, but also offers important insights into the design of multifunctional biomass-based materials for advanced flexible wearable electronics.