Metal–organic frameworks (MOFs) are hybrid porous crystalline networks with tunable chemical and structural properties. However, their excellent potential is limited in practical applications by their hard‐to‐shape powder form, making it challenging to assemble MOFs into macroscopic composites with mechanical integrity. While a binder matrix enables hybrid materials, such materials have a limited MOF content and thus limited functionality. To overcome this challenge, nanoMOFs are combined with tailored same‐charge high‐aspect‐ratio cellulose nanofibrils (CNFs) to manufacture robust, wet‐stable, and multifunctional MOF‐based aerogels with 90 wt% nanoMOF loading. The porous aerogel architectures show excellent potential for practical applications such as efficient water purification, CO₂ and CH₄ gas adsorption and separation, and fire‐safe insulation. Moreover, a one‐step carbonization process enables these aerogels as effective structural energy‐storage electrodes. This work exhibits the unique ability of high‐aspect‐ratio CNFs to bind large amounts of nanoMOFs in structured materials with outstanding mechanical integrity—a quality that is preserved even after carbonization. The demonstrated process is simple and fully discloses the intrinsic potential of the nanoMOFs, resulting in synergetic properties not found in the components alone, thus paving the way for MOFs in macroscopic multifunctional composites.

The potential safety hazard associated to commonly used flame retardant chemicals generates a strong demand for new, sustainable, and high performing solutions to reduce the fire threats of widespread polymer foams. In this work, the production of self‐extinguishing, nonignitable, and flame resistant flexible polyurethane foams by means of simple layer‐by‐layer assembly of graphene oxide nanoplatelets is reported. The process builds a protective exoskeleton that completely wraps the complex 3D structure of the foam and is capable of stopping flame spread in flammability tests and preventing ignition when exposed to heat fluxes typical of developing fires. In addition, treated foams are found able to withstand the penetration of a flame torch, successfully protecting the unexposed side from thermal decomposition for more than 6 min. The outstanding temperature gradient greater than 500 °C cm⁻¹ achieved through the foam thickness makes the performances of these foams comparable to those of a silica aerogel, while maintaining excellent flexibility and toughness. The results reported in this paper represent a tremendous opportunity for the production of a novel class of organic and flexible foams, capable of ensuring unprecedented fire safety properties while relying on an easy, green, and straightforward approach to material design.

The preparation of wood substrates modified by charged inorganic nanoparticles (NPs) diffusing into the internal cell wall structure is investigated for generating functional properties. The flammability problem of wood biocomposites is addressed. NPs applied from colloidal sols carry charge to stabilize them against aggregation. The influence of charge on particle diffusion and adsorption should play a role for their spatial distribution and localization in the wood substrate biocomposite. It is hypothesized that improved dispersion, infiltration, and stability of NPs into the wood structure can be achieved by charge control diffusion, also restricting NP agglomeration and limiting distribution to the wood cell wall. Cationic and anionic silica NPs of ≈30 nm are therefore allowed to diffuse into bleached wood. The influence of charge on distribution in wood is investigated as a function of initial sol concentration. Transparent wood is fabricated by in situ polymerization of a thiol‐ene in the wood pore space. These biocomposites demonstrate excellent flame retardancy with self‐extinguishing characteristics. The approach has potential for commercial fabrication of flame retardant transparent composites for glazing and other building applications.

New sustainable materials produced by green processing routes are required in order to meet the concepts of circular economy. The replacement of insulating materials comprising flammable synthetic polymers by bio-based materials represents a potential opportunity to achieve this task. In this paper, low-density and flame-retardant (FR) porous fiber networks are prepared by assembling Layer-by-Layer (LbL)-functionalized cellulose fibers by means of freeze-drying. The LbL coating, encompassing chitosan and sodium hexametaphosphate, enables the formation of a self-sustained porous structure by enhancing fiber-fiber interactions during the freeze-drying process. Fiber networks prepared from 3 Bi-Layer (BL)-coated fibers contain 80% wt of cellulose and can easily self-extinguish the flame during flammability tests in vertical configuration while displaying extremely low combustion rates in forced combustion tests. Smoke release is 1 order of magnitude lower than that of commercially available polyurethane foams. Such high FR efficiency is ascribed to the homogeneity of the deposited assembly, which produces a protective exoskeleton at the air/cellulose interface. The results reported in this paper represent an excellent opportunity for the development of fire-safe materials, encompassing natural components where sustainability and performance are maximized.