Highly temperature resistant cellulose nanofiber/polyvinyl alcohol hydrogel using aldehyde cellulose nanofiber as cross-linker

Polyvinyl alcohol (PVA) based hydrogels, generally prepared by freeze–thaw methods, are commonly used in the field of wound dressing. Biomedical materials require rigorous sterilization prior to use which can result in the decomposition of hydrogen bonded PVA hydrogels during conventional high temperature sterilization. In this study, a highly temperature resistant cellulose nanofiber/polyvinyl alcohol (CNF/PVA) hydrogel is prepared using functionalized CNF as a chemical cross-linker. NaIO₄ is utilized to selectively oxidize CNF to increase CNF chemical reactivity. The crystallinity and the thermal decomposition temperature of CNF show a decreasing trend with the increase of oxidant content. The CNF/PVA hydrogels are synthesized with functional CNF and PVA at 80 °C under acidic condition through aldolization. The mechanical strength and modulus of the hydrogel (CNF-3/PVA) with more chemical cross-linking networks are 0.43 MPa and 0.25 MPa, respectively. The hydrogel exhibits a water content (82.7%) close to that of the organism tissue and not decompose or swell much during the high-temperature sterilization treatment. In addition, the produced hydrogel shows the same softening effect as living tissue.