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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. [ABSTRACT FROM AUTHOR]

Particle‐stabilized emulsions, so‐called Pickering emulsions (PEs), are a promising low‐tech avenue to precisely engineered materials for applications in drug delivery, catalysis, or water remediation. The particle assembly at the liquid–liquid interface provides superior stability and an adjustable permeability, which is a key parameter for controllable compound capture and release. However, understanding the complex factors that control the particle assembly in detail is a still‐remaining challenge limiting practical applications of PEs in an industrial framework. In this study, the properties of oil‐in‐water emulsions, stabilized by cellulose nanocrystals (CNCs), are investigated. It is shown how high ionic strength leads to low polydispersity droplets, with restricted permeability across the oil‐water interface due to the dense packing of the CNC layer. In contrast, lower electrolyte concentration enables enhanced uptake through the interface, while providing the required stability for the reusability of the material. The authors continue to study the impact of the electrolyte content on the dynamic responses of the emulsions, leading to a liquid–liquid system with tunable cyclic uptake and release levels. Overall, the results highlight the potential of nanocellulose‐stabilized emulsions as tunable and robust material platform with well‐defined permeability characteristics—made in a simple way. [ABSTRACT FROM AUTHOR]

The performance of thin carboxylated cellulose nanofiber-based (CNF) membranes as proton exchange membranes in fuel cells has been measured in situ as a function of CNF surface charge density (600 and 1550 μmol g−1), counterion (H+ or Na+), membrane thickness and fuel cell relative humidity (RH 55 to 95%). The structural evolution of the membranes as a function of RH, as measured by Small Angle X-ray Scattering, shows that water channels are formed only above 75% RH. The amount of absorbed water was shown to depend on the membrane surface charge and counter ions (H+ or Na+). The high affinity of CNF for water and the high aspect ratio of the nanofibers, together with a well-defined and homogenous membrane structure, ensures a proton conductivity exceeding 1 mS cm−1 at 30 °C between 65 and 95% RH. This is two orders of magnitude larger than previously reported values for cellulose materials and only one order of magnitude lower than Nafion 212. Moreover, the CNF membranes are characterized by a lower hydrogen crossover than Nafion, despite being ≈30% thinner. Thanks to their environmental compatibility and promising fuel cell performance the CNF membranes should be considered for new generation proton exchange membrane fuel cells. [ABSTRACT FROM AUTHOR]

Carbon coating is essential for active materials in electrochemical applications that are often insulators or poor conductors. A conventional conformal carbon coating can hinder the ion diffusion to and from the active material and form an isolated conducting network. Especially, active materials with very large volume expansion, e.g., silicon, can destroy the carbon coating during lithiation, which makes conformal carbon coating inappropriate. This paper presents a novel textile-like carbon wrapping that provides efficient electron and ion diffusion paths via a wide-range carbon network and pores. The textile-like carbon wrapping can reduce the electrical contact loss during cycling through the wide-range carbon network, which makes it a suitable carbon coating for materials that undergo volume expansion. A textile-like carbon-wrapped silicon is formed by pyrolysis of a dried suspension of silicon nanoparticles mixed with enzymatically hydrolyzed cellulose nanofibers. It shows excellent electrochemical performance compared to a conformal carbon-coated silicon. It exhibits a reversible specific capacity of 680 mA h g−1 at 8.0 A g−1 and shows excellent cycling stability (capacity retention of 94.5% after 500 cycles at 2.0 A g−1) with high Si content (95.71 wt%). Therefore, this novel textile-like carbon wrapping can be utilized in many electrochemical applications instead of the conventional carbon coating, especially for active materials that undergo large volume expansion. [ABSTRACT FROM AUTHOR]

Silicon is a good alternative to conventional graphite anode but it has bad cycling and rate performance. To overcome these severe problems, extensively interconnected silicon nanoparticles using carbon network derived from ultrathin cellulose nanofibers were synthesized. Ultrathin cellulose nanofibers, an abundant and sustainable material, entangle each silicon nanoparticle and become extensively interconnected carbon network after pyrolysis. This wide range interconnection provides an efficient electron path by decreasing the likelihood that electrons experience contact resistivity and also suppresses the volume expansion of silicon during lithiation. In addition, Ultrathin cellulose nanofibers are carboxylated and therefore adhesive to silicon nanoparticles through hydrogen bonding. This property makes ultrathin cellulose the perfect carbon source when making silicon composites. As a consequence, it exhibits 808 mAh g −1 of the reversible capacity after 500 cycles at high current density of 2 A g −1 with a coulombic efficiency of 99.8%. Even at high current density of 8 A g −1 , it shows a high reversible discharge capacity of 464 mAh g −1 . Moreover, extensively interconnected carbon network prevents the formation of a brittle electrode with a water-based binder. Therefore, this remarkable material has a huge potential for LIBs applications. [ABSTRACT FROM AUTHOR]

Cellulose is difficult to solubilize and undergoes thermal decomposition prior to melting. In recent years ionic liquids have been evaluated as solvents of cellulose. In the regeneration process the non-solvent governs the resulting material's crystallinity. Water adsorbs to amorphous cellulose, acts as plasticizer and lowers the T g , hence the degree of crystallinity will affect the potential strain induced reorientation. We prepared regenerated cellulose fibers form ionic liquid using different non-solvents. The influence of shear forces upon cellulose chain alignment during extrusion was simulated in silica based upon rheological measurements. The regenerated fibers had different physical, morphological and mechanical properties. Molecular re-orientation in fibers induced by mechanical strain, at humidities above the T g , resulted in much improved mechanical properties with the Young's modulus reaching 23.4 ± 0.8 GPa and the stress at break 504.6 ± 51.9 MPa, which is comparable to commercially available cellulose fibers. [ABSTRACT FROM AUTHOR]