Cellulose nanofibrils (CNF) show high modulus and strength, and are already used in industrial applications. Mechanical properties of neat CNF films or CNF-polymer matrix nanocomposites, are usually much better than for polymer matrix composite films reinforced by clay, graphene, graphene oxide or carbon nanotubes. In order to obtain small CNF diameter and colloidal stability, chemical modification has so far been necessary, but this increases cost and reduces eco-friendly attributes. In this study, an unmodified holocellulose CNF (Holo-CNF) with small diameter is obtained from mildly peracetic acid (PAA) delignified wood fibers. CNF is readily defibrillated by low energy kitchen blender processing. The hemicellulose coating on individual fibrils in the wood plant cell wall is largely preserved in Holo-CNF. This “native” CNF shows well-preserved native fibril structure in terms of length (2.1µm), diameter (<5 nm), high crystallinity, high cellulose molar mass, electronegative charge, and limited mechanical processing damage. The hemicellulose coating contributes mechanical properties and high optical transmittance for CNF nanopaper, which can otherwise only be achieved with chemically modified CNF. The CNF nanopaper shows superior mechanical properties with a Young’s modulus of 21 GPa and an ultimate strength of 320 MPa. Moreover, hemicellulose imparts recyclability from dried state. Altogether, this native CNF represents a class of colloidally stable, eco-friendly, low cost CNF of small diameter for large-scale applications of nanopaper and nanomaterials.

The sustainable development of engineering biocomposites has been limited due to a lack of bio‐based monomers combining favorable processing with high performance. Here, the authors report a novel and fully bio‐based transparent wood biocomposite based on green synthesis of a new limonene acrylate monomer from renewable resources. The monomer is impregnated and readily polymerized in a delignified, succinylated wood substrate to form optically transparent biocomposites. The chemical structure of the limonene acrylate enables diffusion into the cell wall, and the polymer phase is both refractive index‐matched and covalently linked to the wood substrate. This results in nanostructured biocomposites combining an excellent optical transmittance of 90% at 1.2 mm thickness and a remarkably low haze of 30%, with a high mechanical performance (strength 174 MPa, Young's modulus 17 GPa). Bio‐based transparent wood holds great potential towards the development of sustainable wood nanotechnologies for structural applications, where transparency and mechanical performance are combined.

Wood templates are promising biobased substrates that can be functionalized for controlled nanostructure, and the development of novel nanotechnologies. A sustainable, selective and versatile chemical functionalization platform for cellulosic wood templates is developed. Bulk wood templates are delignified using peracetic acid, and the nanoporous delignified wood templates are functionalized with cyclic anhydrides (maleic, itaconic and succinic) from renewable resources. The synthetic pathway uses solvent-free reaction conditions, short reaction times, and has possibilities for chemical recovery. Anhydrides become covalently attached inside the nanoporous wood cell wall and yields wood templates with lower moisture sorption, preserved nano- and ultrastructure, and high degree of esterification with carboxyl content as high as 3.93 mmol g⁻¹. The functionalization platform enables interface tailoring at the molecular scale with possibility for further reaction and covalent modifications. This is demonstrated by the preparation of transparent wood biocomposites. The biocomposites exhibit controlled wood–polymer interfacial adhesion with high optical transmittance. The favorable interaction mechanisms at the cell wall level result in mechanically strong biocomposites.

Designing polymeric materials for closed-loop material streams is the key to achieving a circular society. Here, a library of macrocyclic carbonates (MCs) was designed by a facile and direct one-pot, two-step synthesis approach without the use of a solvent at a 10 g scale. We demonstrate that anionic polymerization with tert-butoxide enables the ultrafast ring-opening polymerization (ROP) of MCs with high conversion (>97%) within seconds (3–10 s) at ambient temperature. The polymerization rate depends on the odd or even number of methylene groups between the carbonate linkages in the MCs, and not the overall ring size, yielding an “odd–even” effect. This polymerization rate is related to the difference in molecular conformation of the MCs, as determined by X-ray crystallography. The polymers (polypenta-, hexa-, heptamethylene carbonate) were subsequently regenerated back to their original MCs at a high selectivity (95–99 mol %) and good yields (70–85%), hence taking a step toward closing the loop on these long alkyl chain polycarbonates.

Design of nanocellulose-based composite materials suitable for selective disintegration, recovery and recycling of individual components is of great scientific and technical interest.