Cellulose nanocomposites

Article By:

Gardner, Douglas J. Department of Forest Management, School of Forest Resources, University of Maine, Orono, Maine.

Last reviewed:2012

DOI:https://doi.org/10.1036/1097-8542.YB120278

Cellulose is a natural polymer material made of β-d-glucopyranose units that are linked together by (1→4)-glycosidic bonds. The length of a native cellulose molecule is at least 5000 nm, corresponding to a chain with about 10,000 glucopyranose units. Cellulose molecules are linear and are aggregated through secondary valence forces, including van der Waals forces and both intra- and intermolecular hydrogen bonds. In a plant cell wall, the linear cellulose chains, referred to as microfibrils, are approximately 3.5 × 10 nm in cross-sectional dimension and of indeterminate length. The microfibrils have both crystalline and amorphous regions. The linear cellulose molecules and the supermolecular microfibrils have a dominant influence on the behavior of plant cell walls as a material. The molecular organization of cellulose in the plant cell wall contributes to its unique polymer properties. For improving the interaction or interfacial adhesion of cellulose with other materials, including polymers, in the creation of nanocomposites, it is possible to chemically modify its surface. Cellulose reactivity or a lack thereof depend on its structure. To modify cellulose structure, the highly ordered hydrogen-bonded lattice must be disrupted by swelling or dissolution. The reactive sites on cellulose, which may be derivatized, are the three hydroxyl groups indicated as C-2, C-3, and C-6 in Fig. 1.

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