Sulfonated cellulose beads were prepared by oxidation of Cladophora nanocellulose to 2,3-dialdehyde cellulose followed by sulfonation using bisulfite. The physicochemical properties of the sulfonated beads, i.e., high surface area, high degree of oxidation, spherical shape, and the possibility of tailoring the porosity, make them interesting candidates for the development of immunosorbent platforms, including their application in extracorporeal blood treatments. A desired property for materials used in such applications is blood compatibility; therefore in the present work, we investigate the hemocompatibility of the sulfonated cellulose beads using an in vitro whole blood model. Complement system activation (C3a and sC5b-9 levels), coagulation activation (thrombin-antithrombin (TAT) levels) and hemolysis were evaluated after whole blood contact with the sulfonated beads and the results were compared with the values obtained with the unmodified Cladophora nanocellulose. Results showed that neither of the cellulosic materials presented hemolytic activity. A marked decrease in TAT levels was observed after blood contact with the sulfonated beads, compared with Cladophora nanocellulose. However, the chemical modification did not promote an improvement in Cladophora nanocellulose hemocompatibility in terms of complement system activation. Even though the sulfonated beads presented a significant reduction in pro-coagulant activity compared with the unmodified material, further modification strategies need to be investigated to control the complement activation by the cellulosic materials.

Natural biomaterials, including polysaccharides and amino acids, provide a sustainable source of functional carbon materials for electric energy storage applications. We present a one-pot reductive amination process to functionalize 2,3-dialdehyde cellulose (DAC) beads with chitosan and l-cysteine to provide single (N)- and dual (N/S)-doped materials. The functionalization enables the physicochemical properties of the materials to be tailored and can provide carbon precursors with heteroatom doping suitable for energy storage applications. Scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis were used to characterize the changes to the beads after functionalization and carbonization. The results of X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy verified that the doping was effective, while the nitrogen sorption isotherms and pore-size distributions of the carbonized beads showed the effects of doping with different hierarchical porosities. In the electrochemical experiments, three kinds of carbon beads [pyrolyzed from DAC, chitosan-crosslinked DAC (CS-DAC) and l-cysteine-functionalized DAC] were used as electrode materials. Electrodes of carbonized CS-DAC beads had a specific capacitance of up to 242 F g(-1) at a current density of 1 A g(-1). These electrodes maintained a capacitance retention of 91.5% after 1000 charge/discharge cycles, suggesting excellent cycling stability. The results indicate that reductive amination of DAC is an effective route for heteroatom doping of carbon materials to be used as electrode active materials for energy storage.

A series of sustainable activated carbons (ACs) with large surface areas and tunable pore sizes is synthesized from Cladophora cellulose and its chemically modified derivatives in a one-step physical carbonization/activation process. The molecular structure of the cellulose precursors and the carbonization/activation atmosphere (N₂ or CO₂) significantly influence the pore structure of the ACs. When using oxidized cellulose and its further cross-linkages as the precursor, the ACs have a large volume of ultramicropores (pore diameter < 0.8 nm). Activation in CO₂ results in ACs with surface areas up to 1241 m² g⁻¹. These ACs have a high CO₂ uptake capacity (2.29 mmol g⁻¹ at 0.15 bar, 5.52 mmol g⁻¹ at 1 bar; 273 K) and a high CO₂–over–N₂ selectivity (42 at 273 K). In addition, the capacity of the ACs to adsorb vapors of volatile organic compounds (VOCs) is remarkable, with values up to 0.97 mmol g⁻¹ at very low VOC concentrations (200 ppmv). The ACs have ultrahigh VOCs–over–N₂ selectivity up to 9.35 × 10³ at 293 K for 0.02 vol%/99.8 vol% of benzene/N₂ mixture. It is anticipated that these ACs will be useful as sorbents for the postcombustion capture of CO₂ and for indoor removal and direct air capture of various VOCs.

Abstract Poor cycling stability and safety concerns regarding lithium (Li) metal anodes are two major issues preventing the commercialization of high‐energy density Li metal‐based batteries. Herein, a novel tri‐layer separator design that significantly enhances the cycling stability and safety of Li metal‐based batteries is presented. A thin, thermally stable, flexible, and hydrophilic cellulose nanofiber layer, produced using a straightforward paper‐making process, is directly laminated on each side of a plasma‐treated polyethylene (PE) separator. The 2.5 µm thick, mesoporous (≈20 nm average pore size) cellulose nanofiber layer stabilizes the Li metal anodes by generating a uniform Li+ flux toward the electrode through its homogenous nanochannels, leading to improved cycling stability. As the tri‐layer separator maintains its dimensional stability even at 200 °C when the internal PE layer is melted and blocks the ion transport through the separator, the separator also provides an effective thermal shutdown function. The present nanocellulose‐based tri‐layer separator design thus significantly facilitates the realization of high‐energy density Li metal‐based batteries.

Micrometer sized 2,3-dialdehyde cellulose (DAC) beads were produced via a recently developed method relying on periodate oxidation of Cladophora nanocellulose. The produced dialdehyde groups and pristine hydroxyl groups provided the DAC beads with a vast potential for further functionalization. The sensitivity of the DAC beads to alkaline conditions, however, limits their possible functionalization and applications. Hence, alkaline-stable and porous cellulose beads were prepared via a reductive amination crosslinking reaction between 2,3-dialdehyde cellulose beads and chitosan. The produced materials were thoroughly characterized with different methods. The reaction conditions, including the amount of chitosan used, conditions for reductive amination, reaction temperature and time, were investigated and the maintained morphology of the beads after exposure to 1 M NaOH (aq.) was verified with SEM. Different washing and drying procedures were used and the results were studied by SEM and BET analysis. Furthermore, FTIR, TGA, EDX, XPS, DLS and elemental analysis were performed to characterize the properties of the prepared beads. Finally, the alkaline-stable porous chitosan cross-linked 2,3-dialdehyde cellulose beads were applied as adsorbent for the dye Congo red. The crosslinked beads displayed fast and high adsorption capacity at pH 2 and good desorption properties at pH 12, providing a promising sorption material.

Herein 2,3-dialdehyde cellulose beads prepared from Cladophora green algae nanocellulose were sulfonated and characterized by FTIR, conductometric titration, elemental analysis, SEM, ζ-potential, nitrogen adsorption–desorption and laser diffraction, aiming for its application as a potential immunosorbent material. Porous beads were prepared at mild reaction conditions in water and were chemically modified by sulfonation and reduction. The obtained 15 µm sized sulfonated beads were found to be highly charged and to have a high surface area of ~ 100 m² g⁻¹ and pore sizes between 20 and 60 nm, adequate for usage as immunosorbents. After reduction of remaining aldehyde groups, the beads could be classified as non-cytotoxic in indirect toxicity studies with human dermal fibroblasts as a first screening of their biocompatibility. The observed properties make the sulfonated cellulose beads interesting for further development as matrix material in immunosorbent devices.

Softwood sulfite bleached cellulose pulp was oxidized with Oxone (R) and cellulose nanofibers (CNF) were produced after mechanical treatment with a high-shear homogenizer. UV-vis transmittance of dispersions of oxidized cellulose with different degrees of mechanical treatment was recorded. Scanning electron microscopy (SEM) micrographs and atomic force microscopy (AFM) images of samples prepared from the translucent dispersions showed individualized cellulose nanofibers with a width of about 10 nm and lengths of a few hundred nm. All results demonstrated that more translucent CNF dispersions could be obtained after the pretreatment of cellulose pulp by Oxone (R) oxidation compared with the samples produced without pretreatment. The intrinsic viscosity of the cellulose decreased after oxidation and was further reduced after mechanical treatment. Almost translucent cellulose films were prepared from the dispersions of individualized cellulose nanofibers. The procedure described herein constitutes a green, novel, and efficient route to access CNF.

A novel method for favored primary alcohol oxidation of cellulose was developed. Cellulose pulp andCladophora nanocellulose were oxidized in a one-pot procedure by Oxone® (2KHSO5$KHSO4$K2SO4)and efficient reaction conditions were identified. The effects of the reaction on the morphology,viscosity and chemical structure of the products obtained were studied. The primary alcohol groupswere oxidized to carboxyl groups and the content of carboxyl groups was determined byconductometric titration. SEM, capillary-type viscometry and XRD were applied to characterize theproducts and to investigate the influence of oxidation. For the first time, low-cost and stable Oxone®was used as a single oxidant to oxidize cellulose into carboxyl cellulose. The oxidation is an inexpensiveand convenient process to produce carboxylic groups on the surface of the cellulose fibers and to makethe cellulose fibers charged. Particularly, this method can avoid the use of halogens and potentially toxicradicals and constitute a green route to access carboxylated cellulose. Further, sodium bromide could beused as a co-oxidant to the Oxone® and increase the carboxylic acid content by 10–20%. The Oxone®oxidation is a promising method for oxidation of cellulose and might facilitate the production of CNC.

Calcium ion-crosslinked nanofibrillated cellulose (NFC) hydrogels were investigated as potential materials for wound healing dressings. The physicochemical properties of the hydrogels were examined by rheology and water retention tests. Skin cells and monocytes were selected for application-oriented bio-compatibility studies. The NFC hydrogels presented entangled fibrous networks and solid-like behavior. Water retention tests showed the material's potential to maintain a suitable moist environment for different type of wounds. The hydrogels did not affect dermal fibroblasts monolayer cultures upon directcontact, as cell monolayers remained intact after application, incubation and removal of the materials. Inflammatory response studies with blood-derived mononuclear cells revealed the inert nature of the hydrogels in terms of cytokine secretion and reactive oxygen species production. Results highlight the great potential of ion-crosslinked NFC hydrogels for the development of advanced wound dressings, where further functionalization of the material could lead to improved properties towards the healing of specific wound types.

Porous materials have potential applications in gas capture and storage and heterogeneous catalysis.¹ We have developed a series of porous polymers (PPs) and porous carbons (PCs) with high surface areas and tunable pore sizes. They were studied as potential sorbents for CO₂ separation and volatile organic compounds (VOCs) removal.²

  The PPs were synthesized by Schiff base polycondensations. The sustainable PCs were synthesized from natural abundant celluloses by a physical carbonization/ activation process. All the PPs and PCs had ultramicropores and displayed relatively high CO₂ uptakes (0.93-2.29 mmol/g at 0.15 bar, 2.20-5.52 mmol/g at 1 bar; 273 K) and CO₂-over-N₂ selectivities (31-90 for CO₂/N₂ mixtures with 15 vol%/85 vol% at 273 K). In addition, the ACs displayed remarkable adsorption capacity for vapors of VOCs with values up to 0.97 mmol/g at very low VOC concentrations (200 ppmv) and with ultrahigh VOC-over-N₂ selectivity (9.35 × 10³ at 293 K for 0.02 vol%/99.8 vol% of benzene/N₂ mixture).

  The diverse synthesis routes and rich functionalities of PPs allowed further post-modification to improve their performance in CO₂ capture. The PPs modified by alkyl amines induced chemisorption of CO₂, which was confirmed by the study of in situ infrared (IR) and solid-state ¹³C NMR spectroscopy. As a result, the amine-modified PPs had a large CO₂ capacity and very high CO₂-over-N₂ selectivity at the CO₂ concentrations relevant for post-combustion capture of CO₂.