Metal–organic frameworks such as ZIF-8, grown in situ on nanocellulose (NC), have gained significant attention in recent years due to the versatility of the processing route and multifaceted application in the field of environmental remediation and biomedical applications. However, insights into the interactions between NC and MOF precursors and MOF structure evolution during in situ synthesis are limited or nonexistent. We report the kinetics of ZIF-8 formation on a nanocellulose (NC) aqueous suspension and in water at room temperature, monitored in real time after the addition of ZIF-8 precursors. This is the first study revealing the mechanism of ZIF-8 formation in the presence of nanocellulose. A combination of synchrotron-based small-angle (SAXS) and wide-angle X-ray scattering (WAXS) enabled us to compare the time evolution of the radius of gyration obtained from SAXS and the extent of crystallization determined by WAXS. Based on the SAXS data, we propose a new model that accounts for the initial rapid formation of primary particles, which subsequently evolve into medium-range structures before growing into the final product. Scanning electron microscopy images supported this mechanism, showing smaller particles at the beginning of the reaction and confirmed interparticle interactions, showing nanocellulose particles decorating the surface of the final ZIF-8 crystals. We demonstrate that the concentration of the starting metal salt significantly influences the kinetics of the reaction but has little effect on the ZIF-8 particle size. In contrast, increasing the NC concentration led to a reduction in the final ZIF-8 particle size, while having a negligible impact on the reaction rate and affording a minor decrease in surface area and micropore volume. We show that at the lower NC concentration that was studied the ZIF-8 particles were covered by NC, and no reduction in porosity was observed. Moreover, the kinetics of formation was shown to be independent of the NC functional group and morphology under the conditions used in this study.

We have produced foams from cellulose nanofibrils from upcycled cotton (upCNF) and wood (wCNF) through unidirectional (UIT) and multidirectional ice-templating (MIT) and investigated the structural humidity response through in-situ WAXS, SAXS, and micro tomography (μCT) between 10 and 95 % relative humidity (RH). The upCNF and wCNF WAXS patterns displayed a shape- and position shift as the RH was increased, with a compression in the (200) direction and an elongation in the (004) direction. The average separation distance extracted from the 1D SAXS patterns revealed no significant change for the upCNF foams regardless of RH and processing route, while a significant increase was observed for the wCNF foams. The μCT measurements of the upCNF foams showed a slight shift in macropore distribution towards larger pores between 50 and 80 % RH which can be attributed to the weakening and partial disintegration of the pore wall as more moisture is introduced. The humidity-induced structural alterations of the upCNF foam were significantly lower compared to the wCNF foams, confirming our claim of upCNF being more moisture resistant than wCNF foams.

Metal-organic frameworks (MOFs) are porous polymeric networks with unique characteristics. Nevertheless, these materials' intrinsic fragility, powdery form, limited processibility, and delicate handling pose significant difficulties for commercial applications. Herein, we reported large-scale production and processing of nanocellulose/leaf-like zeolitic imidazolate framework (ZIF-L), denoted as NanoCelloZIF-L, using Experimental Paper Machine (XPM). Four tanks (volume of 300 L for each tank) with a total volume of 1200 L were used to process the NanoCelloZIF-L sheet with varied weight percentages of the materials 0–30 wt%. The materials were processed with and without starch (0.3 wt%) to improve the properties of the final products. The procedure enabled a straightforward, highly efficient method that might be easily implemented for large-scale production of composite materials based on ZIFs. NanoCelloZIF-L sheets were used as an adsorbent to remove water pollutants, including heavy metals and organic dyes. They offered a 90 % adsorption efficiency for organic dyes. They can effectively remove heavy metals for single or mixed metal species, offering adsorption capacities of 460.5 mg/g with high selectivity toward Fe³⁺ ions.

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 expanding field of lignin-containing nanocellulose offers a sustainable alternative to fossil-based substances in applications such as packaging, coatings, and composites. This has underscored the importance to explore the impact of raw materials due to the complexities of lignin structures and different raw fiber characteristics, which plays a significant role in determining the properties of the resultant lignin-rich cellulose materials. This study presents a detailed investigation and comparison on the production and structure-property relationships of lignin-containing microfibrillated cellulose (LMFC) fibers prepared from unbleached softwood and hardwood kraft pulps. The microfibrillation process was analyzed for both softwood and hardwood pulps, comparing the results across various stages of fibrillation. Distinguishing features of lignin structures in softwood and hardwood pulps were identified through Py-GC/MS analysis. Additionally, Digital Image Correlation was employed to investigate the varying failure patterns in LMFC films derived from different wood species. Softwood-derived LMFC films demonstrate less strain-concentrated regions and strain variation, attributed to the formation of more physical crosslinking joints by the elongated fibers. Consequently, softwood-origin LMFC films displayed superior load-sharing and enhanced tensile strength (287 MPa) compared to those derived from hardwood. Additionally, the denser lignin structures in unbleached softwood pulp further boosted the stiffness of resultant softwood-derived films. Upon recycling, LMFC films exhibited superior recovery of mechanical properties following drying, suggesting their significant potential for widespread commercial use.

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.

Nitric oxide (NO) holds promise for wound healing due to its antimicrobial properties and role in promoting vasodilation and tissue regeneration. The local delivery of NO to target cells or organs offers significant potential in numerous biomedical applications, especially when NO donors are integrated into nontoxic viscous matrices. This study presents the development of robust cellulose nanofibril (CNF) hydrogels designed to control the release of nitric oxide (NO) generated in situ from a NO-donor molecule (S-nitrosoglutathione, GSNO) obtained from the nitrosation of its precursor molecule glutathione (GSH). CNF, efficiently isolated from sugar cane bagasse, exhibited a high aspect ratio and excellent colloidal stability in water. Although depletion forces could be observed upon the addition of GSH, this effect did not significantly alter the morphology of the CNF network at low GSH concentrations (<20 mM). Ionic cross-linking with Ca²⁺ resulted in nontoxic and robust hydrogels (elastic moduli ranging from 300 to 3000 Pa) at low CNF solid content. The release rate of NO from GSNO decreased in CNF from 1.61 to 0.40 mmol. L^–1·h^–1 when the nanofibril content raised from 0.3 to 1.0 wt %. The stabilization effect monitored for 16 h was assigned to hydrogel mesh size, which was easily tailored by modifying the concentration of CNF in the initial suspension. These results highlight the potential of CNF-based hydrogels in biomedical applications requiring a precise NO delivery.

Bone defect repair, particularly in the alveolar region, remains a significant hurdle in periodontics. In recent years, the spotlight in regenerative medicine has fallen on 3D-printed bone scaffolds, especially those constructed of polylactic acid (PLA) infused with hydroxyapatite. This research introduced a novel approach by developing a 3D-printed PLA scaffold enriched with hydroxyapatite derived from fish skin waste (FSHA). Mechanical compression tests revealed that the 3D-printed PLA-FSHA scaffolds had a compressive strength (13.4 ± 5.53 MPa) in the same ballpark as their reference PLA counterparts (20.3 ± 1.08 MPa). Scanning electron micrographs highlighted an average pore size in the scaffold (572 ± 33 μm) conducive to angiogenesis and facilitating cell migration and proliferation. In vitro, cytotoxicity was ascertained using the MTT assay on L929 fibroblast cells. Further in vitro cytocompatibility assessments through actin-DAPI staining and measurements of bone regeneration markers - alkaline phosphatase, osteocalcin and osteopontin-demonstrated that the PLA-FSHA scaffolds not only were biocompatible but also showcased performance on par with the commercial graft, osseograft. This lays the foundation for future in vivo evaluations of bone regenerative capabilities.

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.

Bionanocomposites comprising biobased polymers and nanosized bio-based fillers are novel materials with tunable properties and have diverse applications in packaging, environmental remediation and the biomedical sector. Bionanocomposite materials also have a significant role to play in the implementation of a functional circular economy.

In this themed issue, leading researchers from academia and industry were invited to submit reviews or their latest research on topics aligned to the development of bionanocomposites from renewable resources. Studies dealing with waste conversion to bio-based products and the development of bionanocomposites have been included in this issue. This issue consists of 7 research articles.

As guest editors of this themed issue, we acknowledge all the authors and reviewers who have contributed to its publication. We would also like to thank the technical support team at the Royal Society of Chemistry for their assistance in preparing this themed issue.