Combined impact of moisture and temperature on cellulose nanocrystal interface degradation by molecular dynamics simulation

Cellulose nanocrystals (CNCs), derived from abundant natural cellulose, possess exceptional properties including low weight, bioavailability, and high mechanical performance. During shear loading, CNCs exhibit unique stick–slip behavior, making them excellent toughening materials for CNC neat films and nanocomposite. However, the failure behavior at the interface under specific conditions, particularly moisture and temperature, remains unclear. The study utilized molecular dynamics (MD) simulations to quantitatively investigate the hydrothermal effect on the degradation of CNC interface. The degradation mechanism induced by moisture and temperature was indicated through the reduction of adhesive energy and peak force with the consideration of hydrogen bonds. The simulation results showed that the role of water molecules in the interfacial failure depends their content. Water acted as a binder at low moisture levels, while at high moisture levels, it acted as a lubricant. Besides, temperature had a more pronounced impact on the interfacial shear performance. Our simulation results can be used as input in micromechanical models to bridge the gap between the macroscopic and microscopic behavior of films and nanocomposites.