Effect of Process Conditions and Colloidal Properties of Cellulose Nanocrystals Suspensions on the Production of Hydrogel Beads

Abstract

The influence of the physical, rheological, and process parameters on the cellulose nanocrystal (CNC) drops before and after external gelation in a CaCl2 solution was investigated. The dominant role of the CNC’s colloidal suspension properties, such as the viscous force, inertial, and surface tension forces in the fluid dynamics was quantitatively evaluated in the formation of drops and jellified beads. The similarity and difference between the behavior of carbohydrate polymers and rod-like crystallites such as CNC were enlightened. Pump-driven and centrifugally-driven external gelation approaches were followed to obtain CNC hydrogel beads with tunable size and regular shape. A superior morphological control—that is, a more regular shape and smaller dimension of the beads—were obtained by centrifugal force-driven gelation. These results suggest that even by using a simple set-up and a low-speed centrifuge device, the extrusion of a colloidal solution through a small nozzle under a centrifugal field is an efficient approach for the production of CNC hydrogel beads with good reproducibility, control over the bead morphology and size monodispersion.

Encapsulation of Trichoderma harzianum with nanocellulose/carboxymethyl cellulose nanocomposite

“…CaCl 2 is widely used as a crosslinking agent in the production of alginate beads (Lan et al, 2018). The Ca 2+ ions can form ionic interactions between the negatively charged groups of cellulose (and its derivatives) and nanocellulose molecules (after previous functionalization of the polymers to induce charges), resulting in the formation of beads when the polymeric dispersion is dripped into CaCl 2 solution (de Carvalho et al, 2016;Ferrari et al, 2021). The beads formed were kept in the salt solution for 30 min, washed with distilled water to remove the excess salt, and then dried in an oven at 28 • C for 48 h. Additionally, some of the beads were lyophilized to remove residual water, prior to characterization using FTIR, TGA, and DSC techniques.…”