Effect of polymeric spherulite coatings on optical properties of chiral nematic cellulose nanocrystal films

Cellulose nanocrystals (CNCs) have received an abundance of attention because of their distinctive chiral nematic structure and exceptional optical characteristics. However, the use of free-standing films is constrained by the inherent stiffness and brittleness. In this work, CNC films with robust mechanical properties are prepared by simply coating them with polymeric spherulites. Maleic anhydride-grafted polypropylene (PP-g-MA) is used to coat CNC films. The optical properties of coated films were also analyzed using polarized optical microscope. It is observed that the circular extinction patterns for the coated CNC film were created by the radial symmetry of banded spherulites, which were responsible for the perception of the optical transmission bands of the CNC film. Interfacial anchoring plays a crucial role in enhancing the overall performance and properties of the composite system. The future development of numerous portable functional components needing improved optical, mechanical, and thermal qualities of CNC films is made possible by this protective coating approach.