Iridescent solid nanocrystalline cellulose films incorporating patterns and method for their production

摘要

A new method to produce solid nanocrystalline cellulose (NCC) films containing patterns by differential heating of aqueous suspensions of NCC has been discovered. When acid-form NCC suspensions are dried by heating to temperatures above 50 °C, darkening of the NCC can occur, while neutral forms of NCC can produce iridescent chiral nematic films by heating to temperatures up to 105 °C. Placing materials of different thermal conductivity beneath the container containing an evaporating NCC suspension results in watermark-like patterns of different iridescent colour imprinted within the film structure. Other colloidal rod-like particles can be employed in place of nanocrystalline cellulose (NCC), for example chitin or chitosan.