Preparation and Properties of Cellulosic Nanomaterials

Abstract

What are the reasons for the effervescence and explosion of the scientific literature during the last decade in the field of cellulosic and other polysaccharide nanomaterials? First, the raw materials are abundant, available in a variety of forms, renewable, non-toxic, low density, and biodegradable. In addition, it is well known that unexpected and attractive properties can be observed when decreasing the size of a material down to the nanoscale. Different forms of cellulose nanomaterials, resulting from a top-down deconstructing strategy (cellulose nanocrystals - CNCs, cellulose nanofibrils - CNFs) or bottom-up strategy (bacterial cellulose - BC), can be prepared. Multiple mechanical shearing actions applied to cellulosic fibers release more or less individually the nanofibrils. A controlled strong acid hydrolysis treatment can be applied to cellulosic fibers allowing the selective dissolution of non-crystalline domains and disengagement of nanocrystalline cellulose regions. The mechanical modulus of crystalline cellulose is the basis of many potential applications. With a Young's modulus of the order of 100-130 GPa and a specific surface of several hundred m2·g-1, these cellulosic nanomaterials have a significant capacity of reinforcement at low filler content. Several properties reviewed in this article are impacted by the nanoscaling process.