Evaluating the Influence of Twisted Structure on Mechanical Properties of Biopolymer Films using LIPIT

Bio-derived nanomaterials such as cellulose nanocrystals (CNCs) and chitin nanocrystals (ChNCs) garnered considerable interest due to their tunable mechanical and biodegradable properties. These nanoparticles possess a high aspect ratio with rod-like morphology which impart them with the ability to self-organize into a “cholesteric” liquid crystal phase in an aqueous suspension. The twisted structure of the cholesteric phase makes CNCs/ChNCs suitable candidates for the bottom-up fabrication of the “Bouligand Structure” found in natural materials that exhibit high mechanical strength. However, the intrinsic brittleness of CNCs/ChNCs films, unlike the natural Bouligand structure, limits their application scope. Moreover, little is understood about the mechanical properties of the pristine CNCs/ChNCs films. In this contribution, we study the relationship between liquid crystal structure and mechanical properties of CNCs/ChNCs films at the micro and nanoscales. Coefficient of restitution experiments based on laser-induced projectile impact testing (LIPIT) is used to evaluate the effects of pitch and pitch angle of the twist on the mechanical properties of CNCs/ChNCs films. These results provide insights into the role of chirality on the mechanical behavior of these composites and enable the development of advanced composite materials with tunable mechanical properties.