This project investigates the fundamental mechanisms governing water interactions and drying behavior in TEMPO-mediated oxidized cellulose nanofibrils (CNFs), a class of renewable, biodegradable materials with exceptional mechanical properties and biocompatibility. These features make CNFs strong candidates for next-generation sustainable composites, films, and biomedical devices. However, to enable their practical deployment, especially in applications where precise water management is critical, it is essential to understand how water behaves in and around CNFs during drying—particularly under low humidity conditions (<20 wt% water), where complex water–nanofiber interactions are not yet fully understood. This project adopts an interdisciplinary approach that integrates molecular simulations with experimental characterization to systematically probe the role of water in CNF systems. A central focus lies in understanding how different counterions—specifically lithium (Li⁺), sodium (Na⁺), magnesium (Mg²⁺), and calcium (Ca²⁺)—modulate water structure, dynamics, and evaporation behavior in the nanofibril environment. These ions are known to influence the electrostatic environment and local hydration structure, potentially affecting both the kinetics and thermodynamics of the drying process. In parallel, the role of spatial confinement—such as in thin films or dense CNF networks—is explored, as confinement strongly alters water behavior at the nanoscale. Molecular dynamics simulations are a critical tool in this project. However, short production runs often fail to provide statistically robust results, particularly for dynamic properties such as the diffusion coefficients of water and ions. Reliable extraction of these parameters requires longer simulation times to improve sampling quality and reduce noise in mean squared displacement and velocity autocorrelation analyses. Extended simulations will enable more accurate modeling of ion-specific effects and water mobility across different hydration and confinement conditions. Preliminary simulations have already yielded valuable insights into water coordination and ion–cellulose interactions. These results are guiding the design of the experimental phase, which will validate and expand upon the computational findings. The combination of atomistic and mesoscale simulations with experimental techniques such as X-ray scattering and gravimetric analysis will enable a multiscale understanding of water transport, binding, and removal in CNF-based systems. Ultimately, the outcomes of this project will support the rational design of CNF materials optimized for specific drying pathways and end-use conditions. These results will contribute to the development of environmentally friendly, high-performance materials in sectors ranging from packaging to biomedicine, where moisture sensitivity and processability remain key challenges.