Svitlana Filonenko

Nonaqueous deep eutectic solvent (DES)-based high internal phase double emulsions (double-HIPEs) were employed as a novel platform for synthesizing polyHIPE beads with a well-defined spherical shape and a 3D-interconnected macroporous structure. A primary DES₁/O HIPE was prepared using the monomer styrene and the cross-linker divinylbenzene (10:1 molar ratio) as the oil (continuous) phase (20 vol %) and stabilized with the nonionic Span 60 surfactant (10, 20, or 30 wt %). It was then dispersed at a controlled addition rate (0.9 or 1.8 mL/min) into DES₂, a surfactant and water-free suspension medium, forming stable DES₁/O/DES₂ double-HIPEs that were polymerized via free-radical polymerization. Different DESs were used as the polar phases (DES₁ and DES₂) and consisted of choline chloride with urea (ChCl), glycerol (G), or ethylene glycol (EG) (1:2 molar ratio), yielding viscosities of 750, 250, and 37 cP, respectively. The porosity and shape of the resulting spherical polyHIPE beads were finely tailored by adjusting the surfactant concentration, DES₁ and DES₂ viscosities, and primary HIPE addition rate, avoiding the complex fabrication techniques typically required in aqueous-based systems. Under these controlled conditions, uniform spherical beads were easily obtained with average bead diameters (D_b) ranging from 2.6 ± 0.2 to 1.5 ± 0.1 mm, average pore diameters (D_p) from 20.2 ± 0.2 to 10.2 ± 0.1 μm, degree of openness (O) from 18.2 to 12.3%, and specific surface areas (S _BET) from 5.78 to 2.8 m²g^–1. By contrast, aqueous W/O/W double emulsions prepared under analogous conditions produced irregular beads with collapsed porosity, reflecting insufficient stability during polymerization. In addition, the millimeter-sized spherical polyHIPE beads with the highest S _BET= 5.78 m²g^–1 (D_b = 1.8 ± 0.2 mm, O = 18.2%, D_p = 10.8 ± 0.3 μm) exhibited mechanical robustness (elastic modulus = 1.01 ± 0.21 MPa), a hydrophobic surface (contact angle of 95°), and easy packability into a glass column, enabling their use in a flow-through sorption process for the removal of emulsified engine oil from water. These materials achieved an oil sorption capacity (Q) of 383.04 mgg^– 1 and oil removal efficiency (%R) of 92% at a high water-flow rate through the packed column (F_rate = 288.5 mLmin^–1) and were reused for over five sorption/desorption cycles without losing their oil uptake capacity. By comparison, a monolithic polyHIPE obtained by direct polymerization of the primary emulsion exhibited a lower S _BET = 3.2 m²g^–1 (O = 16.4%, D_p = 13.9 ± 0.6 μm), difficult packability, lower oil uptake capacity (%R = 81% and Q = 337.8 mgg^–1) and flowability (F_rate = 40 mLmin^–1), underscoring the advantages of the spherical beads. These results revealed that nonaqueous DES-based double emulsions constitute a novel platform for templating spherical polyHIPE beads, paving the way for the incorporation of a wide range of monomers and functional nanoparticles (e.g., via Pickering templating) to produce application-tailored materials where spherical geometry, controlled pore architecture, and surface functionality are critical.

Natural eutectic solvents (NaESs) for the valorization of biomass have been gaining interest in recent years. However, almost no study is available on their impact on the physicochemical and mechanical properties of polysaccharides and their plasticizing power during extraction. In this work, microwave-assisted extraction was combined with hydrophilic NaESs to intensify the extraction process of polysaccharides from the lichen Evernia prunastri, modifying their mechanical properties to obtain viscoelastic materials. With this integrated extraction/formulation process, the energy consumption and production time were reduced by 35% and 23%, respectively. Four solvent systems, namely, sorbitol : betaine, lactic acid : betaine, glycerol : betaine and oxalic acid : proline, were tested. The maximum polysaccharide extraction yield of 44.31% was obtained with oxalic acid : proline at 100 °C for 5 min. For lactic acid : betaine and glycerol : betaine, the highest yields were reached at 120 °C for 15 min (35.93% and 32.93%, respectively). The type of eutectic solvent chosen had a significant impact on the physicochemical and mechanical properties of the extracted polysaccharides. With glycerol : betaine, polysaccharides with higher molecular weights were obtained. Directly drying after the extraction, a flexible material was obtained, exhibiting elastic behavior under deformation, with a Young's modulus of 20.6 MPa and a maximum deformation of 94%. With lactic acid : betaine, a material exhibiting a plastic deformation of up to 245% and less resistance (Young's modulus of 12.1 MPa) was obtained. With oxalic acid : proline, the material exhibited elastic deformation of up to 24% and a Young's modulus of only 9.9 MPa. A particular interest was also given to the valorization of the residual solid obtained from the extraction into high-value-added artificial humic substances.

Direct ink writing is especially relevant to the biomedical field due to the customizable extrusion and the possibility of creating pre‐designed architectures. Abundant natural polymers are sustainable and biocompatible alternatives to synthetic and persistent polymers. The printing of pure nanocellulose suspensions proves difficult due to low solid loadings, high shrinkage, as well as non‐fitting rheology. Emulsion gels (emulgel) alternatives gain attention in the field owing to their favorable viscoelastic properties and the possibility of creating multiphase systems. The authors’ sulfur‐free cationic cellulose nanocrystals (CNC) of low degree of substitution enable straightforward deployment in Pickering emulsions. An emulgel ink co‐stabilized by cationic CNC and α‐cyclodextrin is introduced as an interfacial inclusion complex. All ink components are natural and biodegradable compounds. The produced emulgel inks allow for high fidelity printing and minimum shrinkage upon drying that relaxes the need for supports, even in complex overhanging structures. A low yield stress (230–270 Pa) facilitates the inclusion of cells for biomedical applications into the formulation. The emulgel can be tuned to the desired rheological properties and be equipped with both polar and apolar compounds due to the biphasic system, making it a promising platform for biocompatible additive manufacturing.

Natural polymers are attractive sustainable materials for production of fibers and composite materials. Cotton and flux are traditional plants used to produce textiles with comforting properties while technologies like Viscose, Lyocell and Ioncell-F allowed to extent fiber use into regenerated cellulose from wood. Neither natural nor man-made fibers completely satisfy the needs for cellulose based fabrics boosting development of new approaches to bring more sustainability into the fashion. Technologies like Spinnova are arising based on the spinning of mechanically pretreated cellulose materials with a lower environmental impact though challenged by the fiber quality and strength related to the inconsistency of the mechanical fibers. Nanoscaled cellulose is an excellent solution to improve the consistency of spin fibers, but charges introduced by traditional chemical treatments prevent rebuilding native hydrogen bonding and compromise the mechanical properties especially in wet conditions. We used nanocellulose with low surface charge isolated using reactive eutectic media to spin fibers able to restore the native hydrogen bonding and enable constitutional mechanical strength of cellulose. We performed un-optimized spinning to reveal the intrinsic properties of the fibers and confirmed the preserved strength of wet fibers compliant with the low surface charge enabling further engineering towards cotton-like fabric from wood.

Hydrothermal carbonization (HTC) converts wet biomass into hydrochar and a process liquid, but aromatic compounds in the products have been reported as a roadblock for soil applications as they can inhibit germination, plant growth, and soil microbial activity. Here, we compared HTC and hydrothermal humification (HTH) of cow manure digestate while varying the initial alkaline content by adding KOH. HTH converted 37.5 wt% of the feedstock to artificial humic acids (A-HAs) found in both solid and liquid, twice that of HTC. HTH reduced phenolic and furanic aromatic compounds by over 70% in solids and 90% in liquids. The A-HAs in HTH resemble natural humic acids (N-HA), based on FTIR, UV–vis spectra, and CHN and XRD analysis. The HTH liquid possesses 60% higher total organic carbon (TOC) than HTC. Although one-third of TOC can be precipitated as A-HA, a high TOC concentration remains in the liquid, which is shown to be mainly organic acids. Therefore, we also evaluated the HTC and HTH liquids for anaerobic biomethane production, and found that compared to the original cow manure digestate, the HTH liquids increased methane yield by 110.3 to 158.6%, a significant enhancement relative to the 17.2% increase seen with HTC liquid. The strong reduction in organic acids during biogas production from HTH liquid indicates the potential for converting soluble byproducts into methane, while maintaining high A-HAs levels in the solid product. Graphical Abstract

Natural polymers are attractive sustainable materials for production of fibers and composite materials. Cotton and flux are traditional plants used to produce textiles with comforting properties while technologies like Viscose, Lyocell and Ioncell-F allowed to extent fiber use into regenerated cellulose from wood. Neither natural nor man-made fibers completely satisfy the needs for cellulose based fabrics boosting development of new approaches to bring more sustainability into the fashion. Technologies like Spinnova® are arising based on the spinning of mechanically pretreated cellulose materials with a lower environmental impact though challenged by the fiber quality and strength related to the inconsistency of the mechanical fibers. Nanoscaled cellulose is an excellent solution to improve the consistency of spin fibers, but charges introduced by traditional chemical treatments prevent rebuilding native hydrogen bonding and compromise the mechanical properties especially in wet conditions. We used nanocellulose with low surface charge isolated using reactive eutectic media to spin fibers able to restore the native hydrogen bonding and enable constitutional mechanical strength of cellulose. We performed un-optimized spinning to reveal the intrinsic properties of the fibers and confirmed the preserved strength of wet fibers compliant with the low surface charge enabling further engineering towards cotton-like fabric from wood.

This study introduces an alternative approach towards lignocellulosic biomass fractionation. For this purpose, reactive eutectic media (REM) based on ammonium formate and different organic acids are investigated, possible products are identified, and the REM are employed for lignin extraction and terminal isolation of cellulose pulp from beech wood. The method promises a considerable process intensification by simultaneous separation of high purity cellulose pulp, lignin isolation as a cationically modified species, and production of value‐added chemicals from reaction products of the REM. This study puts a further focus on the generated cellulose pulp and investigates it with respect to surface charge and fiber length.