Fabrication of Chitosan-Based Multifunctional Supramolecular Hydrogel for Efficient Wood Preservation

Traditional wood preservatives have faced severe constraints in practical applications, primarily due to significant environmental hazards and health risks. Herein, we report an eco-friendly chitosan-based supramolecular hydrogel (QTFPA) consisting of quaternized chitosan (QCS), tannic acid (TA), ascorbyl palmitate (PA), and Fe3+ ions (Fe), which is fabricated via the synergistic effects of hydrogen bonding, ionic bonding, and metal coordination. This supramolecular hydrogel possesses good mechanical strength and stability. Moreover, it exhibits excellent adhesion performance, injectability, and self-healing properties, enabling strong adhesion to wooden surfaces and facilitating the maintenance of its protective barrier continuity in wood preservation applications. The intrinsic antifungal activity of QCS, TA, and the synergistic photothermal antifungal effect of the Fe-TA coordination complex jointly endow the QTFPA supramolecular hydrogel with potent inhibitory activity against Coriolus versicolor (C. versicolor). This inhibitory activity is further enhanced under 808 nm near-infrared (NIR) irradiation, with an inhibition rate of 81.39% after 3 days of culturing. A 12-week decay test against C. versicolor further confirmed the decay resistance of the QTFPA supramolecular hydrogel, in which the untreated Pinus sylvestris (P. sylvestris) woods exhibited an average mass loss of 45%, whereas treated wood showed a progressive reduction in mass loss. Specifically, P. sylvestris woods treated at a QCS concentration of 20 mg/mL in hydrogels achieved grade I high decay resistance (with a mass loss of 4.68%), while those treated at QCS concentrations of 5, 10, and 15 mg/mL reached grade II strong decay resistance, with corresponding mass losses of 17.54, 15.67, and 12.63%, respectively. This system provides an effective strategy for developing eco-friendly wood preservatives.