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The chiral nematic self-assembly of aqueous suspensions of cellulose nanocrystals is partially preserved on evaporation of water, but the ordering of the rod-like nanoparticles may become distorted by changes in volume, ionic strength and surface and convective forces during evaporation, thus affecting the morphology and optical properties of the dried film. Proposed applications for these solids with chiral nematic order require confirmation of their structure. A SEM examination of the fracture surface of a slowly-dried film showed a surprisingly regular fan-like pattern which is shown to be characteristic of cross-sections of the left-handed helicoidal arrangement of nanocrystals, where the helicoidal axis was almost perpendicular to the film surfaces. Superimposed on this pattern was what appeared to be a regular porosity, which is postulated to result from pull-out of the nanocrystals oriented orthogonal to the fracture surface.

Tosylation and acylation of cellulose were performed under mild reaction conditions using imidazolium based ionic liquids (ILs) as solvents. The non-degradative nature, lower viscosity, as well as higher solubility of cellulose in [amim]Cl encouraged us to carry out the reactions in this media. The reactions described here were optimised for this particular solvent in order to obtain different cellulose derivatives with high yields, homogeneity and degree of substitution (DS). Two reagents employed for the in situ activation of carboxylic acids were N,N′-carbonyldiimidazole (CDI) and 1-ethyl-3-(3′-dimethylaminopropyl)carbodiimide hydrochloride (EDCI). Final products were characterised by solution and solid-state NMR techniques.