Tracking the structural evolution of cellulose nanocrystal suspensions via small angle light scattering

Abstract Understanding and controlling agglomeration of cellulose nanocrystals (CNCs) is critical to enable their effective use in various applications. Light scattering techniques are powerful tools for studying how CNCs self-assemble in aqueous suspensions. We used small angle light scattering (SALS) and polarized microscopy to study the formation of ordered domains in CNC suspensions of moderate concentration (1–9 wt%) as a function of time and ultrasonication. Concentration, time and ultrasonication all influenced the structure and rate of tactoid formation. Ultrasonication allowed long-range order to develop faster, and at lower concentrations. The cholesteric pitch increased, and more lamellar structures were observed as sonication time increased. Our findings show that history impacts the temporal evolution of the CNC structures in solutions. These structures will likely influence the ultimate ordering of CNCs when they are used to make films or coatings.