Concentration Induced Dimensional Crossover in Nanocellulose Aerogel Morphology

Nanocellulose is an environmentally benign material with an array of potential applications. Using the freeze-drying technique, nanocellulose suspensions can easily be converted into ultra-light aerogels. These highly inert materials have a very high surface area to volume ratio, making them excellent templates for use as catalyst templates. The nanocellulose aerogels can be formed at various densities, and we have achieved materials that are more than 99.8% air in their final composition relying only on physical processing of microcellulose. The structure of these aerogels is highly dependent upon their composition. Up to 98% air concentration, the aerogels are formed by interlocking sheets that are highly two dimensional in character. At lower densities, these sheets become less common and the structure assumes more of a spiderweb consistency. At densities below 99% air concentration, the aerogels are made up almost entirely of one-dimensional strands. These changes in morphology are accompanied by new bonding characteristics including increased tensile strength and an inherent “stickiness” consistent with can der Waals coupling arising from the large number of nanoscale fibers.