Cellulose nanocrystals (CNCs) are widely used in advanced materials due to their unique mechanical and physicochemical properties. However, their interactions with water, particularly in the context of drying, remain poorly understood. The presence of bound water in CNC poses challenges for processing, storage, and applications sensitive to moisture. In this study, we combine molecular simulations and experimental drying investigations to assess the extent of water retention in both native and TEMPO-CNC under different thermodynamic conditions. Our results demonstrate that while native CNCs can be fully dried under low pressure (≤1 mbar) and elevated temperature (110 °C), TEMPO-CNC retain a significant amount of water (1–7 wt%) due to electrostatic interactions between water molecules and the charged surface carboxylic groups and the sodium counter-ions. These findings provide fundamental insights into the drying behavior of functionalized nanocellulose and highlight the importance of considering residual bound water in applications requiring moisture-sensitive performance.

Extracting high-performance nanomaterials from waste presents a promising avenue for valorization. This study presents two methods for extracting cellulose nanofibrils (CNFs) from discarded textiles. Post-consumer cotton fabrics are chemically treated through either cationization with (2,3-epoxypropyl)trimethylammonium chloride or TEMPO/NaBr-catalyzed oxidation, followed by fibrillation to produce Cat-CNFs and TO-CNFs, respectively. Molecular models indicate variations in the effective volume of each grafted group, influencing the true densities of the functionalized fibers. Significant differences in the morphology of the CNFs arise from each functionalization route. Both CNF types exhibit high surface charge (>0.9 mmol g⁻¹), small cross-sections (<10 nm), and high aspect ratios (>35). TO-CNFs have a higher surface charge, whereas Cat-CNFs exhibit a higher aspect ratio and greater colloidal stability across a broader pH range. Cat-CNFs exhibit cross-sections at the elementary fibril level, highlighting the steric impact of the grafted surface groups on fibrillation efficiency. Nanopapers from these CNFs demonstrate high optical transmittance and haze, whereas anisotropic foams show mechanical properties comparable to foams made from wood-based CNFs. This work highlights the potential of post-consumer cotton textiles as a CNF source and the impact of chemical treatment on the properties of the fibers, CNFs, and resulting lightweight materials.

The upcycling of discarded garments can help to mitigate the environmental impact of the textile industry. Here, we fabricated hybrid anisotropic foams having cellulose nanocrystals (CNCs), which were isolated from discarded cotton textiles and had varied surface chemistries as structural components, in combination with xanthan gum (XG) as a physical crosslinker of the dispersion used for foam preparation. All CNCs had crystallinity indices above 85 %, zeta potential values below -40 mV at 1 mM NaCl, and true densities ranging from 1.61 to 1.67 g center dot cm(-3). Quartz crystal microbalance with dissipation (QCM-D) measurements indicated weak interactions between CNC and XG, while rheology measurements showed that highly charged CNCs caused the XG chains to change from an extended to a helicoidal conformation, resulting in changes the in viscoelastic properties of the dispersions. The inclusion of XG significantly enhanced the compression mechanical properties of the freeze-casted foams without compromising their thermal properties, anisotropy, or degree of alignment. CNC-XG foams maintained structural integrity even after exposure to high humidity (91 %) and temperatures (100 degrees C) and displayed very low radial thermal conductivities. This research provides a viable avenue for upcycling cotton-based clothing waste into high-performance materials.

The linear lifecycle of the textile industry contributes to the enormous waste generation of post-consumer garments. Recycling or repurposing of post-consumer garments typically requires separation of the individual components. This study describes a novel and facile chemo-thermo-mechanical method for producing extrudable pellets, involving one-pot, 2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation of post-consumer polycotton textiles, followed by mild mechanical treatment, all without isolating the constituents of the polycotton blend. The oxidized blend with high cellulose and carboxylate content of 1221 ± 82 mmol COO− per kg of cotton, is pelletised into a masterbatch and further in situ extruded into nanocomposite filaments for 3D printing. The carboxyl groups introduced on the polycotton-based filters enable cotton fibrillation into nanoscaled fibers during mechanical treatment and extrusion resulting to a variety of functional and high surface-finish quality models, including filters and fashion accessories. The electrostatic interactions with positively charged species, such as methylene blue (MB), facilitate their adsorption from water while exhibiting promising adsorption capacities. The adsorption of MB follows the Freundlich model and depends on the printed porosity of the filter. A “trash to treasure” concept for textile waste is further corroborated through the use of the developed 3D printing filament into commodity products.

The study of different forms of nanocellulose is a fast-growing field with many advantages. As a biobased polymer, it holds strong promise to replace petrochemical solid supports that need to be phased out. While there are already a plethora of nanocellulose applications, e.g., in the fields of material science, engineering, and water treatment, there is a surprising lack of reports concerning their applications in catalysis and organic chemistry. A crucial property of nanocellulose is its well-defined surface structure, which enables surface modifications to reach useful solid-supported catalysts and reagents. In this perspective, we explore the use of unmodified and modified variants of nanocellulose in organic chemistry. We further propose that the use of mechanochemistry could be a future application to increase the activity and eliminate the requirement for aqueous media due to nanocellulose’s dispersion issues.

Polyethylene terephthalate (PET) is one of the most common plastics and can be cascaded mechanically during its life cycle. However, recycling affects the mechanical properties of the material, and the virgin material is constantly in demand. If a worn material could be depolymerized to its chemical building blocks, then a virgin polymer could be generated from old fibers. In this work, we have developed a benign organo-catalytic depolymerization of PET to yield dimethyl terephthalate (DMT) and ethylene glycol (EG) without the need for purification of generated monomers. By recirculating the solvent and organo-catalyst, a solvent/substrate ratio of 3:1 was achieved. The depolymerization was successfully applied to other polyesters, polycarbonates, and polycotton. The cotton isolated from the polycotton depolymerization was successfully processed into viscose fibers with a tenacity in the range of nonwaste cotton-derived viscose filaments. The global warming potential (GWP) of PET depolymerization was evaluated by using life cycle assessment (LCA). The GWP of 1 kg PET recycling is 2.206 kg CO₂ equivalent, but the process produces DMT, EG, and heat, thereby avoiding the emissions equivalent to 4.075 kg CO₂ equivalent from the DMT, EG, and steam-energy production through conventional pathways. Thus, the net result potentially avoids the emission of 1.88 kg of CO₂ equivalent. The impact of this process is lower than that of waste PET incineration and conventional PET recycling technologies.

Biopolymer-based functional materials are essential for reducing the carbon footprint and providing high-quality lightweight materials suitable for packaging and thermal insulation. Here, cellulose nanocrystals (CNCs) were efficiently upcycled from post-consumer cotton clothing by TEMPO-mediated oxidation and HCl hydrolysis with a yield of 62% and combined with wood cellulose nanofibrils (CNFs) to produce anisotropic foams by unidirectional freeze-casting followed by freeze drying (FD) or supercritical-drying (SCD). Unidirectional freeze-casting resulted in foams with aligned macropores irrespective of the drying method, but the particle packing in the foam wall was significantly affected by how the ice was removed. The FD foams showed tightly packed and aligned CNC and CNF particles while the SCD foams displayed a more network-like structure in the foam walls. The SCD compared to FD foams had more pores smaller than 300 nm and higher specific surface area but they were more susceptible to moisture-induced shrinkage, especially at relative humidities (RH) > 50%. The FD and SCD foams displayed low radial thermal conductivity, and the FD foams displayed a higher mechanical strength and stiffness in compression in the direction of the aligned particles. Better understanding how drying influences the structural, thermal, mechanical and moisture-related properties of foams based on repurposed cotton is important for the development of sustainable nanostructured materials for various applications.

Discarded garments contribute to an environmental crisis worldwide, prompting the development of new strategies for recycling and upcycling. In this work, we present the extraction of nanocellulose from textiles as an underexplored route for upcycling textile garments made of cotton. We summarize the current state of textile waste management worldwide, discuss strategies for extracting nanocellulose from cotton -based textiles, and outline the associated challenges and outlooks in this field. We further aim to highlight the opportunities and advantages of using cotton as a nanocellulose source and stimulate further research in this area.

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.

To make biorefining more environmentally sustainable, preferably residues from forestry should be used and more than one fraction should be upgraded. A third of raw materials from forestry & horbar;tops and branches (T & B)― are either left in the forests or collected and incinerated to a low value. Herein, we apply a fast fractionation to valorize two of the fractions of this forestry residue. The cellulose is converted to textile fibers and all the lignin to hydrocarbons. The environmental sustainability of the novel value chain was studied by life cycle assessment (LCA), and benefits were found in four out of five impact categories. These are important steps to increase fiber production without affecting environmental impact, making biorefining competitive.