Controlling Impact Mitigation of Nanocellulose Films with Bouligand Nanostructures

Cellulose nanocrystals (CNCs), which can be extracted from cellulose, are a promising material for creating synthetic "Bouligand structures", found in natural materials that exhibit high mechanical strength. However, the intrinsic brittleness of CNC films, unlike the natural Bouligand structure, limits their application scope. Moreover, little is understood about the mechanical properties of the pristine CNC films. In this work, we study the relationship between liquid crystal structure and mechanical properties of CNC films at the micro and nanoscales under high speed impact. Coefficient of restitution experiments based on laser ablation-based rebound experiment (LABRE) is used to evaluate the effects of thickness, pitch and extent of swelling over a broad range of impact velocities. We show that the pitch and relative humidity can be used to actively control the energy dissipation during catastrophic impact events.