Understanding wood’s complex nanostructure and interactions inspires the development of bio-mimetic engineering materials with similar structural and performance characteristics. Their strength, stiffness, toughness, and resilience enable them to resist tensions more effectively and adapt to varying mechanical demands, deriving from the alignment of cellulose nanofibers (CNFs) and the cohesion between them. We have utilized a composite dispersion of CNF and a dendritic polyampholyte, Helux, to: (i) assess the simultaneous effect of alignment and interactions on mechanical properties, and (ii) spin functional tough filaments. Amidation chemistry offers the opportunity for post-functionalization of filaments through Helux-accessible amines, which also enhance mechanical properties via covalent cross-linking at elevated temperatures. Composite filaments exhibited 60% higher ultimate strength and roughly five times higher toughness despite lower fibril alignment (as evidenced by wide-angle X-ray scattering) and a corresponding lower elastic modulus in the presence of Helux. We further investigate the trade-off between CNF alignment and mechanical properties using our desktop polarized optical microscopy (POM) flow-stop technique and in-situ small-angle X-ray scattering (SAXS) in conjunction with its digital twin. A lower degree of alignment in composite dispersions is attributed to faster fibril dynamics and higher rotary diffusion in the presence of negatively charged Helux molecules, facilitating de-alignment. However, Helux can ionically interact with multiple fibrils and physically link them together, forming a tougher and stronger 3D network with a denser morphology and fewer voids, owing to its multi-valent nature. Indeed, there is an affinity between these interactions and those formed between cellulose and lignin/hemicellulose in wood.

Sustainable development requires the development of lightweight, sustainable structural materials with excellent mechanical properties derived from renewable resources. This study investigates the fabrication of lignocellulose nanofibrils (LCNFs) from TEMPO-oxidized unbleached pulps by taking advantage of the lignin retention properties. Due to the presence of lignin, unbleached pulp provides hydrophobic and binding properties that aren’t found in traditional nanofibrils (CNFs) obtained from fully-bleached pulp. Microfluidic spinning techniques were employed to produce highly ordered LCNF-based filaments, with an emphasis on two types of filament: K2 (lower lignin content) and K96 (higher lignin content). In addition to environmental benefits, enhancing alignment and mechanical performance, lignin promotes filament structural order and integrity. It is a promising route for producing strong, high-performance filaments from wood fiber raw materials, reducing their environmental footprint and contributing to the development of next-generation sustainable products.

There has been a recent surge of interest in biobased foams for applications ranging from building sustainability (insulation) to biomedicine, pharmaceutics, and electronics (scaffolds). Foams made from nanocellulose are porous and low-density materials with numerous potential applications. This study compares the production energy, structure, and properties of foams made from TEMPO-oxidized lignocellulose nanofibers (TOLCNF) derived from unbleached wood pulp, and TEMPO-oxidized cellulose nanofibers (TOCNF) from bleached cellulose pulp. TOLCNF foams not only demonstrate superior structural integrity and load-bearing capacity (specific Young’s modulus of 37.4 J g^-1 vs. 16.4 J g^-1 for TOCNF) but also exhibit a higher yield during production due to the minimal processing required for unbleached pulp. Furthermore, TOLCNF foams require about 20 % less cumulative energy than TOCNF foams (26 vs. 32 MJ kg^-1), largely owing to the energy-efficient preparation of TOLCNF from unbleached wood pulp. TOLCNF foams also have a significantly lower cumulative energy demand (CED) compared to fossil-based alternatives like expanded polystyrene (EPS) and polyurethane (PU), highlighting their reduced environmental impact. Despite their lightweight nature, TOLCNF foams exhibit competitive compressive strength, making them viable candidates for eco-friendly applications across various industries. Overall, this study demonstrates that TOLCNF foams are an attractive alternative to other bioand fossil-based foams, offering a balance of energy efficiency, higher yield, mechanical performance, and sustainability.

Protein nanofibrils (PNFs) formed from renewable sources are capable of forming highly hierarchical structures that have potential for use in advanced materials and food textures. Hydrolyzing proteins under acidic and heated conditions results in β-sheetrich fibrils, which are known as PNFs. Depending on the protein source, concentration, and post-treatment, the fibrils’ morphology and length can vary significantly. At high concentrations whey protein forms curved and short PNFs, while at low concentrations, long and straight PNFs are obtained. This variability in structure influences the ability of PNFs to assemble hierarchically. Additionally, plant proteins like mung bean proteins can produce PNFs that have unique properties, such as improved foaming. With hydrodynamic assembly methods like microfluidics, a well-aligned microfiber can be created from these PNFs, mimicking the natural fiber formation process seen in materials like silk. In this study, experiments and numerical methods are combined to investigate the flow behavior and alignment of various PNFs using small-angle X-ray scattering (SAXS). Developing new, sustainable materials with enhanced properties can be achieved by understanding the influence of PNF morphology on hydrodynamic alignment and assembly.

We here explore confinement-induced assembly of whey protein nanofibrils (PNFs) into microscale fibers using micro-focused synchrotron X-ray scattering. Solvent evaporation aligns the PNFs into anisotropic fibers and the process is followed in situ by scattering experiments in a droplet of PNF dispersion. We find an optimal temperature at which the order of the protein fiber has a maximum, suggesting that the degree of order results from a balance between the time scales of the forced alignment and the rotational diffusion of the fibrils. Moreover, we observe that the assembly process depends on the nano-scale morphology of the PNFs. Stiff PNFs with a persistence length in the micrometer scale are aligned at the air-water interface and the anisotropy gradually decrease towards the center of the droplet. Marangoni flows often increase entanglements toward the center, leading to complex patterns in the droplet. Flexible fibrils with a short persistence length (< 100 nm) tends to align uniformly throughout the droplet, possibly due to stronger local entanglements. Straight PNFs form smaller clusters with shorter inter-cluster distances due to their tight packing and consistent linear structure. In contrast, curved PNFs form intricate networks with larger characteristic distances and more varied structures because of their flexibility and adaptability.

Natural, high-performance fibers generally have hierarchically organized nanosized building blocks. Inspired by this, whey protein nanofibrils (PNFs) are assembled into microfibers, using flow-focusing. By adding genipin as a nontoxic cross-linker to the PNF suspension before spinning, significantly improved mechanical properties of the final fiber are obtained. For curved PNFs, with a low content of cross-linker (2%) the fiber is almost 3 times stronger and 4 times stiffer than the fiber without a cross-linker. At higher content of genipin (10%), the elongation at break increases by a factor of 2 and the energy at break increases by a factor of 5. The cross-linking also enables the spinning of microfibers from long straight PNFs, which has not been achieved before. These microfibers have higher stiffness and strength but lower ductility and toughness than those made from curved PNFs. The fibers spun from the two classes of nanofibrils show clear morphological differences. The study demonstrates the production of protein-based microfibers with mechanical properties similar to natural protein-based fibers and provides insights about the role of the nanostructure in the assembly process.