Rheology of MXene-reinforced dual-network hydrogels in swollen and unswollen states

We examine the rheological behavior of MXene (MX) reinforced dual network hydrogels based on methacrylated chitosan (CSMA), oxidized dextran (ODXT), and poly(N,N-dimethylacrylamide) (PDMA). Structural characterization using FTIR, TGA, and SEM was performed to assess chemical connectivity, composition, and microstructure and to verify the presence and dispersion state of MX within the hydrogel matrix. Small amplitude oscillatory shear is employed to establish linear viscoelastic properties, while large amplitude oscillatory shear and cyclic strain time protocols are used to probe nonlinear softening, deformation induced damage, and mechanical recovery. Measurements are performed for multiple MX loadings in both unswollen and swollen states to separate interfacial reinforcement from concentration effects associated with hydration. MX addition increases elastic dominance, delays the onset of nonlinearity to higher strain, and improves post-deformation recovery, consistent with enhanced polymer filler coupling and transient interfacial constraints. Uniaxial extension further indicates increased resistance to tensile deformation. Swelling measurements reveal MX dependent changes in water uptake and pore morphology. Together, these shear and extensional data establish how the MX content and hydration state jointly regulate the viscoelastic function of multicomponent hydrogels and provide quantitative guidelines for tuning formulations in soft material applications.