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Developing advanced textiles and fabrics that offer protection against aerosolised chemical and biological hazards is of tremendous interest and is indispensable to the safety of the military personnel. Unfortunately, the extensive protection offered by protective clothing is often accompanied by a reduction in moisture vapour permeability, which increases physiological burden on the user (i.e., transport of sweat away from the body). This study shows that an enhancement in aerosol particulate filtration of a woven textile fabric can be achieved without impeding its water vapour transmission rate through the application of an ultra‐low grammage nanocellulose coating using a simple papermaking approach. Aerosol particulate filtration is realised in the nanocellulose coating through a size‐exclusion mechanism and the filtration efficiency doubled even at a nanocellulose grammage of 0.25 g m−2. As nanocellulose is hygroscopic, water vapour transmission rate remained unchanged compared to the uncoated woven fabric, regardless of the types of nanocellulose coating applied. The work also reports the mechanical robustness of the nanocellulose network fabricated, which is typically the concern in low‐grammage nanofibrous coating. [ABSTRACT FROM AUTHOR]

We demonstrate the construction of water-stable, biocompatible and self-standing hydrogels as scaffolds for the photosynthetic production of ethylene using a bioinspired all-polysaccharidic design combining TEMPO-oxidised cellulose nanofibers (TCNF) and a cereal plant hemicellulose called mixed-linkage glucan (MLG). We compared three different molecular weight MLGs from barley to increase the wet strength of TCNF hydrogels, and to reveal the mechanisms defining the favourable interactions between the scaffold components. The interactions between MLGs and TCNF were revealed via adsorption studies and interfacial rheology investigations using quartz crystal microbalance with dissipation monitoring (QCM-D). Our results show that both the MLG solution stability and adsorption behaviour did not exactly follow the well-known polymer adsorption and solubility theories especially in the presence of co-solute ions, in this case nitrates. We prepared hydrogel scaffolds for microalgal immobilisation, and high wet strength hydrogels were achieved with very low dosages of MLG (0.05 wt%) to the TCNF matrix. The all-polysaccharic biocatalytic architectures remained stable and produced ethylene for 120 h with yields comparable to the state-of-the-art scaffolds. Due to its natural origin and biodegradability, MLG offers a clear advantage in comparison to synthetic scaffold components, allowing the mechanical properties and water interactions to be tailored. [ABSTRACT FROM AUTHOR]

Natural materials, such as silk and cellulose, have an inspiring set of properties, which have evolved over hundreds of millions of years. In this study, cellulose nanocrystals (CNCs) and regenerated silk fibroin (RSF) are combined to evaluate their suitability for filament formation. This is assessed by tuning and characterizing the interactions between these two materials and finally by studying the alignment of the mixtures under shear. To modify the interactions between CNCs and silk, CNCs with varying surface functionalities (sulfate and/or aminosilane groups) are used. The interactions and compatibility of the two components are investigated using quartz crystal microbalance with dissipation monitoring (QCM‐D) and photothermal atomic force microscopy (AFM‐IR), which show that ionic interactions induce sufficient binding between the two components. Then, the alignment of the CNC and silk mixtures is evaluated by shear‐induced polarized light imaging, which indicates that silk can orientate with the CNCs when not covalently bound. Finally, the potential of the materials for filament formation is tentatively demonstrated using an industrial dry‐spinning environment, where CNCs are expected to bring order and alignment, whereas RSF provides soft and more mobile regions to further facilitate the alignment of the final filament structure. [ABSTRACT FROM AUTHOR]

We propose a new method for the extraction of cellulose nanocrystals (CNCs) from post-consumer cotton textiles through surface functionalization followed by mechanical treatment. Cotton-based textiles were esterified using an 85 wt% solution of citric acid at 100 °C, then further fibrillated in a microfluidizer. The final product, citrated cellulose nanocrystals (CitCNCs), was a dispersion of needle-like nanoparticles with high crystallinity. Up to 78 wt% of the cotton fabric was converted to CitCNCs that exhibited higher yields and a higher surface group content than CNCs extracted through H2SO4 hydrolysis, although CitCNCs showed a broader size distribution and decreased thermal stability. Experimental data supported by DFT calculations showed that the carboxyl groups on the CitCNC surface are bonded to cellulose by mono or diester linkages. An early-stage life cycle assessment (LCA) was performed to evaluate the environmental impact of using discarded textiles as a source of cellulose and analyze the environmental performance of the production of CitCNCs. Our work showed a significant reduction in the environmental burden of CNC extraction using post-consumer cotton instead of wood pulp, making clothing a good feedstock. The environmental impact of CitCNC production was mainly dominated by citric acid. As a proof of concept, around 58 wt% of the citric acid was recovered through evaporation and subsequent crystallization, which could reduce climate impact by 40%. With this work, we introduce a catalyst-free route to valorize textiles with the extraction of CitCNCs and how conducting LCA in laboratory-scale processes might guide future development and optimization. [ABSTRACT FROM AUTHOR]

Development of physical properties of bleached eucalyptus kraft pulp is typically based on the refining process. However, many studies have reported that xylan deposition is a viable alternative. As the mechanisms of xylan and cellulose interactions are not clear, the main goal of this study was to achieve a better understanding of these interactions. Considering that a sample of pulp enriched with xylan is a very complex matrix, a model system was developed. Cellulosic thin films were prepared by spincoating and the Langmuir-Schaefer (LS) method from trimethylsilylcellulose (TMSC). Their interactions with xylan were analyzed using the quartz crystal microbalance with dissipation (QCM-D) monitoring technique. The topological changes on cellulose were studied using atomic force microscopy (AFM). For the 13C solid-state nuclear magnetic resonance (NMR) studies, samples were prepared using commercial microcrystalline cellulose (MCC) and xylan. The xylan was extracted from bleached birch kraft pulp using a cold caustic extraction (CCE) method. The QCM-D monitoring showed deposition only with higher concentrations of xylan solution (1 mg · l−1) for the LS method. The AFM images showed that xylan deposits as agglomerates on the cellulose surface, and the NMR experiments showed that there are interactions for the more ordered region of the cellulose fiber and for the less-ordered region. [ABSTRACT FROM AUTHOR]

The exploitation of the effortless self‐assembly behavior of biomass‐based bricks can be seen as a promising route toward the innovative architectures. Here, a straightforward approach is presented where carbohydrate‐based diblock copolymer, polystyrene‐block‐maltoheptaose (PS‐b‐MH), is organized either on a rigid ultrathin film or on a flexible self‐standing film of wood‐derived cellulose nanofibrils (CNFs). During solvent annealing PS‐b‐MH deposited on relatively rough CNF film undergoes spontaneous rearrangement into high‐resolution patterns with a diblock domain spacing of 10–15 nm. The ideal conditions the self‐assembly require weak interactions between block copolymer and the substrate to increase the chain mobility and enable rearrangements. This is exactly how the system behaves. Adsorption studies of PS‐b‐MH on CNF surfaces reveal weak interactions, and the formed PS‐b‐MH layer is soft and mobile. Even the appearance of more challenging vertical orientation formed on smooth CNF substrates is tentatively evidenced by grazing‐incidence small‐angle X‐ray scattering and atomic force microscope indicating favorable surface interactions between CNF and PS‐b‐MH. [ABSTRACT FROM AUTHOR]

In this work, stability of dispersions and foams containing CaCO3-based pigments and cellulose nanofibrils (CNF) was evaluated with the aim to reveal the mechanisms contributing to the overall stability of the selected systems. The utmost interest lies in the recently developed hydrocolloid hybrid CaCO3 pigments and their potential to form bionanocomposite structures when incorporated with CNF. These pigments possess a polyelectrolyte layer deposited on the surface of the particle which is expected to enhance the compatibility between inorganic and organic components. Stability assessment of both dispersions and foams was conducted using turbidity profile scanning. In dispersions, CNF provides stability due to its ability to form a firm percolation network. If surface-modified pigments are introduced, the favourable surface interactions between the pigments and CNF positively influence the stability behaviour and even large macro-size pigments do not interfere with the stability of either dispersions or foams. In foams, the stability can be enhanced due to the synergistic actions brought by CNF and particles with suitable size, shape and wetting characteristics resulting in a condition where the stability mechanism is defined by the formation of a continuous plateau border incorporating a CNF network which is able to trap the inorganic particles uniformly. [ABSTRACT FROM AUTHOR]