Uniaxial orientation of cellulose nanocrystals by zone-casting technique

Abstract

Cellulose nanocrystals (CNCs) are biomass-based nanoparticles with attractive properties. Using a zone-casting technique, transparent films 2 cm wide and 4 cm long, and 2 µm thick, with uniaxially oriented CNCs were prepared from aqueous suspension of CNCs. The nanocrystals were aligned within the entire film perpendicular to the zone-casting direction. The orientation of the CNCs was confirmed by polarized light microscopy, X-ray diffraction and atomic force microscopy. The intensity of the light transmitted through the films depended on its polarization direction and was the strongest for the light polarized perpendicularly to the crystal orientation direction. The orientation of CNCs in the films resulting in optical anisotropy makes them promising materials for applications in optoelectronics.