Fabrication and characterization of nanocrystalline cellulose films prepared under vacuum conditions

When dried under ambient conditions, the self-assembled chiral nematic arrangement of nanocrystalline cellulose (NCC) in suspension can be preserved in NCC films that can reflect light at specific wavelengths, but the process is slow. Rapid preparation of NCC films was first proposed to cast under vacuum conditions to accelerate water evaporation rates and shorten the drying time. Vacuum preparation of NCC films has been found to not only retain the self-assembled structure but to also increase the chiral nematic pitch and red-shift the reflection wavelength of the films. This method provides a new path to prepare NCC iridescent films with tunable reflection wavelengths and reduced time in many areas.