Understanding Nanocellulose–Water Interactions: Turning a Detriment into an Asset

Abstract

Modern technology has enabled the isolation of nanocellulose from plant-based fibers, and the current trend focuses on utilizing nanocellulose in a broad range of sustainable materials applications. Water is generally seen as a detrimental component when in contact with nanocellulose-based materials, just like it is harmful for traditional cellulosic materials such as paper or cardboard. However, water is an integral component in plants, and many applications of nanocellulose already accept the presence of water or make use of it. This review gives a comprehensive account of nanocellulose–water interactions and their repercussions in all key areas of contemporary research: fundamental physical chemistry, chemical modification of nanocellulose, materials applications, and analytical methods to map the water interactions and the effect of water on a nanocellulose matrix.

Thermal Stability of Cellulose Nanomaterials

“…It should be noted that all the reactions described so far have been carried out in an aqueous environment. Surface hydration is essential for the hydrolysis reactions to yield CNMs, as water favors accessibility to the surface hydroxyl groups and the generation of hydronium ions, responsible for the cleavage of the glycosidic bond and the progressive size reduction of cellulose fibers from micro- to nanoscale. , However, excessive water can be detrimental in some cases. , For example, CNMs with flame retardant surface groups tend to adsorb more water (higher hygroscopicity), which favors structural dehydration at low temperatures and charring rather than tar formation . Although effective in preventing oxidative reactions during the pyrolysis of materials, flame retardancy reduces the thermal stability of CNMs .…”

Rheology as a Tool for Fine-Tuning the Properties of Printable Bioinspired Gels

“…Nanocellulose-based materials are very attractive for 3D bioprinting due to the unique characteristics of cellulose, namely printability, mechanical strength, biocompatibility, biodegradability, and high cell viability [ 195 , 196 , 197 , 198 ]. At high shear rates, nanocellulose chains in suspension align and form shear-thinning or shear-thickening thixotropic systems with rapid recovery [ 199 , 200 , 201 ].…”

Isotropic Gels of Cellulose Nanocrystals Grafted with Dialkyl Groups: Influence of Surface Group Topology from Nonlinear Oscillatory Shear

“…Functionalization of the CNCs with different components can significantly change their properties, such as thermal stability and mechanical properties. Therefore, surface chemical modifications face many challenges and at the same time provide more opportunities for new applications. − Various surface modification strategies have been proposed including esterification, etherification, click chemistry, and polymer grafting. , For the surface modification of the sulfate groups, it has been reported that azetidinium salts can be used for conjugation. , Sahlin et al have investigated a number of modified CNC suspensions at different concentrations. Surface loading may also have an effect on the pristine CNC since the proximity of the sulfate groups most likely affects the hydrogen network between different sulfate groups and the solvent, water in this case.…”

“… 9 − 16 Various surface modification strategies have been proposed including esterification, etherification, click chemistry, and polymer grafting. 17 , 18 For the surface modification of the sulfate groups, it has been reported that azetidinium salts can be used for conjugation. 19 , 20 Sahlin et al 20 have investigated a number of modified CNC suspensions at different concentrations.…”