Membranes and separators are crucial components in many processes and devices. The state-of-the-art fossil-based membranes have a high carbon footprint, and polyfluorinated membranes are increasingly phased out. These limitations lead to an inevitable transition that calls for carbon-neutral membranes with the same or even better performance that can be produced at scale and low cost. Cellulose membranes have the potential to fulfill these criteria if they can be tuned for different purposes. A way to tailor cellulose membranes by preparing them from cellulose fibrils of different refining degrees is presented. The membranes’ effective pore size and permeability to PEG, Fluorescein, and different ions were characterized. The membranes were efficiently used as separators in aqueous-based Zn-ion batteries and PEDOT supercapacitors. This work demonstrates a route toward high-performing and versatile cellulose membranes that can be produced at scale in a more sustainable membrane industry.

This study aimed to develop eco-friendly multifunctional nanocellulose (NC) hybrid films with tailored properties for versatile applications including packaging and photovoltaics. Hybrid films composed by cellulose nanocrystals (CNC) and carboxymethylated cellulose nanofibrils (CNF) were produced at various mass ratio (CNC - 100:0 to 0:100). Montmorillonite clay (MTM) was incorporated (50 % by mass) into the CNC:CNF films. CNC-only films easily dispersed in water, but by adding CNF or MTM, the structural integrity was enhanced. Films with ≥50 % CNF and MTM had a strength reduction of 9–35 % and increased brittleness. The hybrid films presented transmittance above 60 % and haze varying from 5 % to 60 % at 550 nm which can be a beneficial for light management. All films kept color stability over 1000 h of artificial sunlight, a critical packaging feature for long-term storage. CNC: CNF films without MTM showed better potential for optoelectronic applications due to higher transmittance and smoother surfaces, while those with MTM presented UV protection (up to 250 nm) and swelling resistance (28–53 %) which could also benefit optoelectronics increasing their lifespan. Balancing the hybrid films composition is key for optoelectronics, while packaging applications tolerate broader compositions. These findings demonstrate the versatility of NC hybrid films in creating sustainable materials for diverse applications.

Non-sustainable single-use plastics used for food packaging needs to be phased out. Films made from cellulose nanofibrils (CNFs) are suitable candidates for biodegradable and recyclable packaging materials as they exhibit good mechanical properties, excellent oxygen barrier properties and high transparency. Yet, their poor water vapour barrier properties have been a major hindrance in their commercialisation. Here, we describe the preparation of 25 μm thick CNF films with significantly improved water vapour barrier properties after deposition of ultrathin polymeric and metallic coatings, parylene C and aluminium, respectively. When first adding a 40 nm aluminium layer followed by an 80 nm parylene layer, i.e. with a combined thickness of less than one percent of the CNF film, a water vapour transmission rate of 2.8 g m−2 d−1 was achieved at 38 °C and 90 % RH, surpassing a 25 μm polypropylene film (4–12 g m−2 d−1). This is an improvement of more than 700 times compared to uncoated CNF films, under some of the harshest possible conditions a packaging material will need to endure in commercial use. The layers showed a good and even coverage, as assessed by atomic force microscopy, and the parylene-coated surfaces were hydrophobic with a contact angle of 110°, providing good water repellency.

Packaging plays a critical role in ensuring food safety and shelf life by protecting against e.g., moisture, gases, and light. Polyethylene (PE) is widely used in food packaging, but it is mainly produced from non-renewable resources and it is an inefficient oxygen and light barrier. In this study, the layer-by-layer (LbL) assembly of a sustainably produced lignin-based polymer (EH) with polyethylenimine (PEI) or chitosan (CH) was used to fabricate (partially or fully) bio-based coatings with the aim of improving barrier properties of PE films. The charge density of EH was calculated using a polyelectrolyte titration method and the hydrodynamic diameters of EH, PEI and CH were determined by Dynamic Light Scattering (DLS). LbL assembly was monitored in situ via Quartz Crystal Microbalance with Dissipation (QCM-D) and Stagnation Point Adsorption Reflectometry (SPAR). PE films were coated with a variable number of PEI/EH or CH/EH bilayers (BL) using an immersive LbL assembly method. Coated films were studied in terms of light-blocking ability, wettability, thermal behaviour, surface structure, as well as oxygen and water vapor barrier properties. QCM-D and SPAR data showed a stepwise multilayer formation and strong interactions between the oppositely charged polymers, with PEI/EH coating having a greater amount of deposited polymer compared to CH/EH coating at the same number of BL. Overall, light barrier properties and wettability of the coated films increased with the number of deposited bilayers. Coated PE films maintained the overall thermal behaviour of PE. A number of BL of 20 was found to be the most promising based on the studied properties. Selected samples showed improved oxygen and water vapor barrier properties, with PEI/EH coating performing better than CH/EH coating. Taken altogether, we demonstrated that a novel and sustainable lignin-based polymer can be combined with PEI or CH to fabricate (partially or fully) bio-based coatings for food packaging.

To model complex biological tissue in vitro, a specific layout for the position and numbers of each cell type isnecessary. Establishing such a layout requires manual cell placement in three dimensions (3D) with micrometricprecision, which is complicated and time-consuming. Moreover, 3D printed materials used in compartmentalizedmicrofluidic models are opaque or autofluorescent, hindering parallel optical readout and forcing serial charac-terization methods, such as patch-clamp probing. To address these limitations, we introduce a multi-level co-culture model realized using a parallel cell seeding strategy of human neurons and astrocytes on 3D structuresprinted with a commercially available non-autofluorescent resin at micrometer resolution. Using a two-stepstrategy based on probabilistic cell seeding, we demonstrate a human neuronal monoculture that forms net-works on the 3D printed structure and can establish cell-projection contacts with an astrocytic-neuronal co-cultureseeded on the glass substrate. The transparent and non-autofluorescent printed platform allows fluorescence-based immunocytochemistry and calcium imaging. This approach provides facile multi-level compartmentaliza-tion of different cell types and routes for pre-designed cell projection contacts, instrumental in studying complextissue, such as the human brain.

Nacre-mimicking nanocomposites based on colloidal cellulose nanofibrils (CNFs) and clay nanoparticles show excellent mechanical properties, yet processing typically involves preparation of two colloids followed by a mixing step, which is time- and energy-consuming. In this study, a facile preparation method using low energy kitchen blenders is reported in which CNF disintegration, clay exfoliation and mixing carried out in one step. Compared to composites made from the conventional method, the energy demand is reduced by about 97 %; the composites also show higher strength and work to fracture. Colloidal stability, CNF/clay nanostructure, and CNF/clay orientation are well characterized. The results suggest favorable effects from hemicellulose-rich, negatively charged pulp fibers and corresponding CNFs. CNF disintegration and colloidal stability are facilitated with substantial CNF/clay interfacial interaction. The results show a more sustainable and industrially relevant processing concept for strong CNF/clay nanocomposites.

This work describes an emulsification-solvent-evaporation method for the preparation of liquid-filled capsules made from cellulose acetate. Two different emulsification techniques were applied: bulk emulsification by high-shear mixing, and droplet generation using microfluidics. The bulk emulsification method resulted in the formation of oil-in-water emulsions composed of an organic mixture of isooctane and cellulose acetate in methyl acetate, and an aqueous phase of high-molecular-weight polyvinyl alcohol (PVA). Upon the solvent evaporation, the emulsion droplets evolved into isooctane-filled cellulose acetate capsules. In contrast, microfluidics led to the formation of monodisperse droplets composed of the aqueous PVA solution dispersed in the organic phase. Upon the solvent evaporation, the emulsion droplets evolved into water-filled cellulose acetate capsules. Owing to the thermoplastic properties of the cellulose acetate, the capsules formed with the bulk mixing demonstrated a significant expansion when exposed to an increased temperature. Such expanded capsules hold great promise as building blocks in lightweight materials.

Despite extensive research on biobased and fiber-basedmaterials, fundamental questions regarding the molecular processesgoverning fiber−fiber interactions remain unanswered. In this study, weintroduce a method to examine and clarify molecular interactions withinfiber−fiber joints using precisely characterized model materials, i.e.,regenerated cellulose gel beads with nanometer-smooth surfaces. Byphysically modifying these materials and drying them together to createmodel joints, we can investigate the mechanisms responsible for joiningcellulose surfaces and how this affects adhesion in both dry and wet statesthrough precise separation measurements. The findings reveal a subtlebalance in the joint formation, influencing the development ofnanometer-sized structures at the contact zone and likely inducingbuilt-in stresses in the interphase. This research illustrates how model materials can be tailored to control interactions betweencellulose-rich surfaces, laying the groundwork for future high-resolution studies aimed at creating stiff, ductile, and/or tough jointsbetween cellulose surfaces and to allow for the design of high-performance biobased materials.

The fabrication of reusable, sustainable adsorbents from low-cost, renewable resources via energy efficient methods is challenging. This paper presents wet-stable, carboxymethylated cellulose nanofibril (CNF) and amyloid nanofibril (ANF) based aerogel-like adsorbents prepared through efficient and green processes for the removal of metal ions and dyes from water. The aerogels exhibit tunable densities (18-28 kg m-3), wet resilience, and an interconnected porous structure (99% porosity), with a pH controllable surface charge for adsorption of both cationic (methylene blue and Pb(II)) and anionic (brilliant blue, congo red, and Cr(VI)) model contaminants. The Langmuir saturation adsorption capacity of the aerogel was calculated to be 68, 79, and 42 mg g-1for brilliant blue, Pb(II), and Cr(VI), respectively. Adsorption kinetic studies for the adsorption of brilliant blue as a model contaminant demonstrated that a pseudo-second-order model best fitted the experimental data and that an intraparticle diffusion model suggests that there are three adsorption stages in the adsorption of brilliant blue on the aerogel. Following three cycles of adsorption and regeneration, the aerogels maintained nearly 97 and 96% of their adsorption capacity for methylene blue and Pb(II) as cationic contaminants and 89 and 80% for brilliant blue and Cr(VI) as anionic contaminants. Moreover, the aerogels showed remarkable selectivity for Pb(II) in the presence of calcium and magnesium as background ions, with a selectivity coefficient more than 2 orders of magnitude higher than calcium and magnesium. Overall, the energy-efficient and sustainable fabrication procedure, along with good structural stability, reusability, and selectivity, makes these aerogels very promising for water purification applications.

Cellulose nanofibril (CNF) hybrid materials show great promise as sustainable alternatives to oil-based plastics owing to their abundance and renewability. Nonetheless, despite the enormous success achieved in preparing CNF hybrids at the laboratory scale, feasible implementation of these materials remains a major challenge due to the time-consuming and energy-intensive extraction and processing of CNFs. Here, we describe a scalable materials processing platform for rapid preparation (<10 min) of homogeneously distributed functional CNF-gibbsite and CNF-graphite hybrids through a pH-responsive self-assembly mechanism, followed by their application in gas barrier, flame retardancy, and energy storage materials. Incorporation of 5 wt % gibbsite results in strong, transparent, and oxygen barrier CNF-gibbsite hybrid films in 9 min. Increasing the gibbsite content to 20 wt % affords them self-extinguishing properties, while further lowering their dewatering time to 5 min. The strategy described herein also allows for the preparation of freestanding CNF-graphite hybrids (90 wt % graphite) that match the energy storage performance (330 mA h/g at low cycling rates) and processing speed (3 min dewatering) of commercial graphite anodes. Furthermore, these ecofriendly electrodes can be fully recycled, reformed, and reused while maintaining their initial performance. Overall, this versatile concept combines a green outlook with high processing speed and material performance, paving the way toward scalable processing of advanced ecofriendly hybrid materials.