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Renewable hemicellulose with a unique structure exhibits a wide range of potential applications. However, it has been a formidable challenge to isolate hemicellulose with an intact structure from lignocellulosic materials. In this study, LiBr·3H2O (LBTH) was used as a green solvent for the effective fractionation of hemicellulose from bleached hardwood kraft pulp (BHKP) under mild conditions (25–85 °C). It was found that hemicellulose in BHKP can be dissolved in LBTH with ease and high selectivity owing to the breaking of hydrogen bonds between hemicellulose and cellulose, and the dissolved hemicellulose can be regenerated with a high degree of polymerization (DP) in the range of 240–264 using ethanol precipitation. The highest removal rate of hemicellulose from BHKP was as high as 95.2%, and the corresponding yield of pure hemicellulose reached 84.3%. Moreover, simultaneously obtained undissolved cellulose pulp through LBTH treatment had a high content of α-cellulose (96.7%), high DP (880), and trace levels of Fe (2 ppm), which met the standard requirement for dissolving pulp for the production of lyocell. In addition, LBTH can be easily recycled to guarantee a green and sustainable process. This work provides a new approach for highly selective fractionation of hemicellulose and cellulose from commercial BHKP based on an efficient and environmentally friendly LBTH treatment, which could be very promising for better valorization of hemicellulose and cellulose in many advanced applications. [ABSTRACT FROM AUTHOR]

Polyelectrolytes with ultra-low glass transition temperatures (Tg) are still a rarity. Herein, we report a series of free-flowing lignin polyelectrolytes with ultra-low Tg in the range of −57–9 °C, namely, deep eutectic supramolecular lignin (DESL). The enabling key principle is to couple the eutectic strategy with supramolecular polymerization, bypassing the exclusive reliance on the large size and flexible cation/anion pairs for flowable polyelectrolytes. Following this principle, various sugars have been successfully integrated with lignosulfonic acid via multiple hydrogen bondings, allowing for bulk yet free-flowing supramolecular materials. These DESLs are processible, adaptive, and compatible to serve as macromolecular solvents and are distinct from traditional polyelectrolyte solutions or chemical modification derivatives. The robustness and versatility of our approach provide a fresh opportunity for booming polyelectrolyte utilization, opening access to a yet unknown fluidic material class. [ABSTRACT FROM AUTHOR]

Developing aqueous stable and catalytic Ti3C2Tx MXene suspensions remains a grand challenge. MXene nanosheets always undergo rapid degradation when exposed to water and oxygen, and the incorporation of reducing or capping agents may deteriorate the intrinsic characteristics of MXenes. Here, we coupled dialdehyde xylan (DAX) with MXene nanosheets to significantly increase the long-term storage of MXene in an aqueous solution (>3 months) with a dramatic enhancement of their room temperature catalytic activity for ultrafast gelation. DAX can form thick and smooth layers on the nanosheets via multiple hydrogen bonds, providing a reduction environment to prevent the occurrence of oxidation. Meanwhile, DAX can accelerate the generation of free radicals from the potassium persulfate (KPS)/MXene pair, reducing the polymerization time of vinyl monomers from ∼30 min to ∼90 s. Moreover, the DAX layer is capable of serving as additional crosslinks by leveraging Schiff base bonds with chitosan (CS), with the elongation at break increasing from 100% to 909%. The resultant MXene-based hydrogel can be further explored as a sustainable sensor for real-time physical signal monitoring. This work offers an enticing prospect for the development of eco-friendly and high-performance MXene-based materials. [ABSTRACT FROM AUTHOR]

Fluidic materials that exhibit an engineered non-Newtonian response are highly desirable in industrial and military applications. For example, shear thickening is highly intriguing in the case of flexible body armor or damping devices; however, shear thinning is more suitable in industrial processes with confining flow or painting. Herein we present a new class of non-Newtonian polymeric fluids with switchable rheological properties being mediated by carbon dioxide (CO2). Several pH-sensitive associative amphiphilic polymers were designed by copolymerizing N,N-dimethylacrylamide (DMA) and N,N-dimethylaminoethyl methacrylate (DMAEMA), followed by hydrophobic modification. In the beginning, polymers carrying an optimal balance of hydrophilic and hydrophobic moieties exhibit shear thinning properties in an alkaline environment. After CO2 aeration, the protonation of tertiary amine groups on the polymer backbone induces coil expansion and promotes interchain cross-linking under shear, leading to an abnormal shear thickening. The fluidic material can regain its shear thinning properties after sparging the solution with N2. Such a gas-controlled process is reversible and clean, which can be performed over multiple cycles. This study taps the potential of CO2 utilization in the dynamic fluidic materials science. [ABSTRACT FROM AUTHOR]

In order to realize the dream of the practical application of hydrogen energy from solar energy and water, it is necessary to use efficient and earth-abundant cocatalysts for photocatalytic H2 evolution. Compared with a one-component cocatalyst, the multicomponent cocatalysts with a synergistic effect can effectively accelerate the separation of photogenerated electron–hole pairs in photocatalysis. Hence, a novel bicomponent Co3S4/Co@C cocatalyst on a CdS semiconductor photocatalyst is successfully synthesized by a one-step hydrothermal method. The Co3S4/Co-CdS photocatalyst obtained exhibits a highly efficient photocatalytic H2 evolution rate of 15.17 mmol h−1 g−1, which is 2.8 times higher than that of Pt-CdS. Furthermore, the quantum efficiency of Co3S4/Co-CdS reaches a maximum value of 16.80% at 475 nm. The significant improvement in the performance is because of the unique energy level structure of the Co3S4/Co-CdS photocatalyst, which has the maximum efficiency of charge separation and migration. This work not only presents a new protocol for constructing bicomponent cocatalysts on a semiconductor structure, but also proves that the bicomponent Co3S4/Co@C is a promising and low-cost cocatalyst. [ABSTRACT FROM AUTHOR]