Reliable characterization of cellulose nanomaterials is critical for their utilization in various applications.

Cellulose is known to interact well with water, but is insoluble in it. Many polysaccharides such as cellulose are known to have significant hydrogen bond networks joining the molecular chains, and yet they are recalcitrant to aqueous solvents. This review charts the interaction of cellulose with water but with emphasis on the formation of both natural and synthetic fiber composites. Covering studies concerning the interaction of water with wood, the biosynthesis of cellulose in the cell wall, to its dispersion in aqueous suspensions and ultimately in water filtration and fiber-based composite materials this review explores water-cellulose interactions and how they can be exploited for synthetic and natural composites. The suggestion that cellulose is amphiphilic is critically reviewed, with relevance to its processing. Building on this, progress made in using various charged and modified forms of nanocellulose to stabilize oil-water emulsions is addressed. The role of water in the aqueous formation of chiral nematic liquid crystals, and subsequently when dried into composite films is covered. The review will also address the use of cellulose as an aid to water filtration as one area where interactions can be used effectively to prosper human life.

This review covers the production, structure, properties and applications of nanowhiskers of cellulose. It is shown that these nanowhiskers can be generated, from various plant sources, with transverse dimensions as small as 3–30 nm, giving a high surface to volume ratio. Since the nanowhiskers are rod-like, it is shown how they can be self-assembled into chiral nematic liquid crystalline structures, not only in solution, but also in the dry state. The production of thin films of cellulose nanowhiskers, by spin coating and in combination with polymer electrolytes, is also covered. A wide range of chemical modification of cellulose nanowhiskers are reviewed; including 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, polymerisation from the surface using Reversible Addition–Fragmentation chain Transfer (RAFT) and Atom Transfer Radical Polymerisation (ATRP), and the rendering of the surface with cationic and anionic charge. The mechanical properties of cellulose nanowhiskers will also be covered, including the measurement of their stiffness using both Raman spectroscopy and Atomic Force Microscopy (AFM) measurements. The final part of the review will cover the applications and potential industrial use of cellulose nanowhiskers; namely for nanocomposite materials, thin films and other applications. Finally, some conclusions, including perspectives and future developments will be presented.