Effect of Ionic Strength and Surface Charge Density on the Kinetics of Cellulose Nanocrystal Thin Film Swelling

Abstract

This work explores cellulose nanocrystal (CNC) thin films (<50 nm) and particle-particle interactions by investigating film swelling in aqueous solutions with varying ionic strength (1-100 mM). CNC film hydration was monitored in situ via surface plasmon resonance, and the kinetics of liquid uptake were quantified. The contribution of electrostatic double-layer forces to film swelling was elucidated by using CNCs with different surface charges (anionic sulfate half ester groups, high and low surface charge density, and cationic trimethylammonium groups). Total water uptake in the thin films was found to be independent of ionic strength and surface chemistry, suggesting that in the aggregated state van der Waals forces dominate over double-layer forces to hold the films together. However, the rate of swelling varied significantly. The water uptake followed Fickian behavior, and the measured diffusion constants decreased with the ionic strength gradient between the film and the solution. This work highlights that nanoparticle interactions and dispersion are highly dependent on the state of particle aggregation and that the rate of water uptake in aggregates and thin films can be tailored based on surface chemistry and solution ionic strength.

Functionalized Nanocellulose/Multiwalled Carbon Nanotube Composites for Electrochemical Applications

“…However, this behavior was not observed for the other three types of nanocellulose/MWCNT membranes. The high degree of sulfation (1.7 mmol/g) of the SCNF likely causes pronounced electrostatic repulsion in deionized water with less than 1 ppb ions, resulting in the SCNF/MWCNT membrane instability . In contrast, screening of some of these nanocellulosic surface charges by the salts present in the electrolyte media (e.g., 10 mM PBS = ionic strength 167 mM) prevents the redispersion of SCNF/MWCNT during electrochemical measurements in this study.…”

Polymerizable Choline- and Imidazolium-Based Ionic Liquids Reinforced with Bacterial Cellulose for 3D-Printing

“…It has been reported earlier that hydrogels based on cellulose nanocrystals also exhibit shear thinning behavior [ 31 ]. However, it is worth noting that high viscosity at low shear rates (in our work, 2.6 × 10 6 and 7976 Pa·s −1 for AA/ImCl and AA/ChCl, respectively) can be achieved with a large content of cellulose nanocrystals (10–25 wt%) [ 73 , 75 ] or by using additional polymers such as poly(ethylene glycol) hexadecyl ether and poly(ethylene glycol) diacrylate [ 94 ]. High viscosity at low shear rates is necessary to prevent material leakage from the nozzle during 3D-printing [ 31 ].…”

The Self‐Assembly of Cellulose Nanocrystals: Hierarchical Design of Visual Appearance

“…As the cholesteric phase concentrates further, the suspension crosses a point of kinetic arrest prior to reaching the solid state. This kinetic arrest occurs when the closely packed nanorods become sufficiently restricted in their ability to relax and rearrange their mutual position and orientation, potentially facilitated by the build‐up of ionic strength upon concentration increase . From this point onwards, evaporation of the remaining solvent will induce a mechanical constraint on the formed gel, with the macroscopic geometry becoming crucial upon the preservation of the cholesteric ordering in the solid state.…”