Using Light Scattering to Measure Aggregation of Cellulose Nanomaterials

As cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF) move to commercial products, simple methods for doing quality control to assess their size, stability and/or dispersion are required. Irreversible aggregation during drying continues to limit the wider commercialization potential of these nanomaterials. If one desires fully dispersed materials, one typically ships slurries, which are 10% solids for CNCs and 1% solids for CNFs. Understanding what governs aggregation and developing simple methods to assess the aggregation state of CNCs and CNFs is essential. We are using a combination of dynamic light scattering (DLS), multiangle static light scattering (MASLS), and small angle light scattering (SALS) to characterize the size (from 5 nm to over 300 nm) and solution behavior of CNC and CNF solutions. SALS is proving to be ideal for identifying aggregates in solution. Moreover, SALS is also being used to measure film products containing cellulose nanomaterials. The scattering of light is proving to be a convenient way to determine the size of the embedded nanomaterials as well as their alignment and dispersion.