In situ modification of cellulose and lignin using deep eutectic solvents for high-strength wood with negligible set recovery.

Lignin-Containing Cellulose Micro/Nanofibril Reinforcement of Sodium Silicate Adhesive: Rheological Structuring and Performance Optimization

The conversion of paper-based industrial residues into lignin-containing cellulose micro/nanofibrils (LCMNFs) provides an opportunity to combine resource valorization with improved adhesive formulations. This study investigated LCMNF produced from alkaline-pretreated unbleached paper tube residues as reinforcement for formaldehyde-free sodium silicate (SS) adhesive, using polyethylene glycol 400 as a dispersing agent. LCMNF was incorporated at 0.5–2.0 wt%, and the rheological, mechanical, and fracture behavior of the modified adhesives was evaluated. Increasing LCMNF content increased viscosity, yield stress, and storage modulus, indicating increased structural resistance within the SS matrix, while all formulations retained the shear-thinning behavior required for processing. Mechanical performance was strongly concentration-dependent. At 0.5 wt%, LCMNF significantly increased strain at break by approximately 40%, whereas 1.0 wt% increased shear modulus by 41%. Both concentrations significantly increased energy to failure without compromising shear strength and exhibited more tortuous fracture morphologies than the neat SS adhesive. Higher LCMNF contents increased microstructural heterogeneity and reduced shear strength. Overall, 1.0 wt% LCMNF provided the most favorable balance of rheological, mechanical, and fracture properties, demonstrating the potential of residue-derived LCMNF for reinforcing SS adhesives and for reintegration into the paper tube production chain.

A lignin-based gel preparation enabled by a deep eutectic solvent pretreatment recycling liquor: towards a full utilization of lignocellulose.

Deep eutectic solvents (DESs) are widely applied in lignocellulosic biomass pretreatment for their green, reusable, and lignin-selective merits. However, lignin accumulation during DES cycling significantly increases solvent viscosity and reduces pretreatment efficiency, severely limiting its sustainable application. To address this bottleneck, we innovatively combined recycled lactic acid/zinc chloride (LA/ZnCl2) DES with acrylic acid (AA), leveraging the synergistic effect of lignin and metal ions to drive free radical polymerization. This strategy enables a simple and efficient preparation for lignin eutectic gels with excellent mechanical properties and low-temperature resistance. The optimized gels (with 3 wt% lignin) exhibited high tensile stress (1.2 MPa), elongation at break (580%), multi-surface adhesion (32 kPa), and maintained a stable electrical conductivity of 1.1 mS cm-1 even at -18 °C. At room temperature, the assembled flexible sensors possessed a fast response speed (160 ms), linear deformation response, and robust electrical stability (<5% signal decay over 700 cycles of 100% deformation). This study pioneered the coupling of DES pretreatment and eutectic gel preparation, facilitating full utilization of lignocellulose and DES components to advance DES-based lignocellulose fractionation, valorization, and the entire biorefinery industry.

Effects of Different Lignin Contents and Water Contents on the Performance of DES-Based Hydrogels

This study fabricated choline–acrylic acid deep eutectic solvent (DES) hydrogels via in situ free-radical polymerization and systematically investigated the individual and co-optimization effects of lignin dosage and water content on the chemical structure, micromorphology, compressive mechanical properties, swelling behavior, and thermal stability of the hydrogels. This work quantitatively uncovers the co-optimization mechanism between the two variables in modulating crosslink density and pore architecture, thereby filling a research gap in the dual-factor co-optimization of biomass-based DES hydrogels. The results reveal that a moderate lignin dosage (0.02 g) generates abundant dynamic hydrogen bonds, densifying the crosslinked network and raising the maximum compressive stress from 0.378 MPa to 0.426 MPa, whereas excessive lignin triggers molecular aggregation and deteriorates mechanical performance. Higher water content dilutes crosslinking sites, reduces network compactness, boosts the swelling ratio while lowering compressive strength, and exerts negligible impacts on thermal degradation characteristics. FTIR analysis confirms that lignin participates in network formation solely through non-covalent hydrogen bonds, without forming new covalent bonds. A comprehensive performance evaluation identifies the optimal formulation as 0.02 g lignin and 60 g water. Although this two-factor optimization strategy provides clear experimental and theoretical guidance for designing sustainable soft materials, the present work still has limitations, including the use of only static laboratory characterizations, with no cyclic mechanical measurements or aging assessments. This study advances the customized performance tuning of lignin-derived DES hydrogels and facilitates the high-value valorization of lignin, which is promising for multifunctional green-material applications, including adsorption, flexible electronics, and biological carriers.

Deep eutectic solvent plasticization of chitosan/distiller's grains prolamin films: Hydrogen bond-driven structural regulation and enhanced food preservation performance.

Developing sustainable, high-performance hydrocolloid packaging remains challenging because polysaccharide films are typically brittle and provide limited barrier protection. Here, we present a synergistic strategy combining distiller's grains prolamin (DGSP) and deep eutectic solvents (DES) to tailor the structure and performance of chitosan (CS) films. CS/DGSP composites were first optimized for protein incorporation, and subsequently plasticized with three choline chloride-based DES (ChCl-glycerol, ChCl-xylitol, and ChCl-urea) at 0.5-2 wt%. Among the ratios tested, a CS/DGSP mass ratio of 2:1 was selected primarily for its superior barrier performance, with favorable film-forming stability and optical properties. DES plasticization, particularly 0.5 wt% ChCl-urea, further enhanced extensibility, UV shielding, and thermal stability, most notably increasing elongation at break to 70.93%, approximately 14-fold higher than that of the non-plasticized control. Structural characterizations indicated that DES-mediated multipoint hydrogen bonding partially replaced polymer-polymer interactions, enabling dual regulation of chain mobility and network densification. This flexible yet compact network suppressed water permeation while maintaining integrity and homogeneity. Strawberry preservation tests confirmed the superior ability of the optimized film to retard moisture loss, shrinkage, and microbial spoilage without compromising sensory quality. These findings provide a DES-assisted protein-polysaccharide design strategy that enables high-value DGSP utilization and offers mechanistic insights into structure-property relationships for sustainable packaging.

Internal plasticization and in-situ siloxane crosslinking synergistic strategy for enhancing wet-state strength and flexibility of regenerated cellulose films.

Regenerated cellulose films are promising sustainable alternatives to petroleum-based plastics, but their intrinsic brittleness and fatal plasticizer migration under humid conditions cause catastrophic mechanical failure. Herein, a synergistic internal plasticization and in-situ crosslinking strategy is proposed to overcome this bottleneck. Polyethylene glycol (PEG400) was infiltrated into the cellulose network to unlock chain mobility, followed by hexadecyltrimethoxysilane modification to construct a robust Si-O-C/Si-O-Si covalent network on the film surface. This surface architecture effectively prevented leaching of the plasticizer from the matrix and rendered the surface highly hydrophobic, with a water contact angle of 112.46°. The optimal composite film (RC-H0.2) exhibited excellent dry and wet tensile strengths of 24.0 and 19.3 MPa, achieving an 80.4% wet-to-dry strength retention. Furthermore, multiple refractive boundaries arising from the coexistence of PEG400 and dispersed siloxane oligomers endowed the film with high transparency (90.9%), haze (72.9%), and water vapor transmission. Consequently, the film achieved a dynamic moisture balance in strawberry packaging, delaying decay until the sixth day, and underwent complete visual disintegration in soil within 56 days. This work provides a practical pathway for designing highly durable, water-resistant biobased flexible packaging.

Enhancing mechanical durability and moisture stability in low-energy citric acid-crosslinked carboxymethyl cellulose films for cherry tomato preservation