Mechanistic insight into homogeneous catalytic crosslinking behavior between cellulose and epoxide by explicit solvent models

An in-situ dissolving-co-crosslinking strategy for fabricating high-strength, wet-stable, and biocompatible multiscale cellulosic paper-based plastics

Developing degradable plastics with excellent mechanical strength and wet stability from renewable and biodegradable biomass resources remains challenging. Here, we propose a simple one-step strategy for the in-situ multiscale dissolution of cellulose and crosslinking with 1,4-butanediol diglycidyl ether (BDDE) within a mixture of BDDE and AlCl3/ZnCl2 aqueous solution at room temperature. This strategy enables the synthesis of cellulosic paper-based bioplastics with high mechanical strength and wet stability from cellulose paper. In this process, conventional cellulose paper is partially dissolved, and simultaneously, BDDE forms chemical crosslinking with undissolved micro-level, nano-level cellulose fibers and dissolved cellulose macromolecules through an autocatalytic effect from AlCl3/ZnCl2 aqueous solution, resulting in multiscale physicochemical entanglements and multiple hydrogen bonds. Hence, the prepared bioplastic's dry and wet strength reached 58.2 MPa and 24.2 MPa, respectively, about 6.9 times and 71.2 times higher than untreated paper-based materials. The prepared bioplastic showed excellent wet stability, biosafety, and biodegradability. The density functional theory (DFT) simulation data indicates that Al3+, Zn2+ ions, and freely hydrated hydrogen protons are crucial to the dissolving-co-crosslinking system. This strategy involves only green and recyclable chemicals, offering a promising pathway for producing strong and biodegradable cellulosic paper-based bioplastics as an alternative to nondegradable plastics.

Catalytic Effects of Water-Solvated Metal Cations in Epoxy-Amine Curing through Hydrogen Bonds and Metal-Ligand Interactions

Hydrogen bonds and metal-ligand interactions catalyze the epoxy-amine cross-linking reactions. Through a detailed quantum chemical study, it was demonstrated that water, through hydrogen bond formations, acts as a better catalyst than amines in the epoxy-amine cross-linking reactions. The presence of various solvated metal cations (Na+, Mg2+, and Al3+) results in the formation of metal-ligand interactions with both epoxy and amine moieties. A comprehensive investigation of these interactions has been performed in the study to demonstrate that the presence of these cations in small quantities effectively catalyzes the epoxy-amine reactions. The energetic analysis of different metal-epoxy-amine complexes suggests the inhibitory nature of Al3+ toward the extent of cross-linking.

Algal carbohydrate polymers: Catalytic innovations for sustainable development

Algal polysaccharides, harnessed for their catalytic potential, embody a compelling narrative in sustainable chemistry. This review explores the complex domains of algal carbohydrate-based catalysis, revealing its diverse trajectory. Starting with algal polysaccharide synthesis and characterization methods as catalysts, the investigation includes sophisticated techniques like NMR spectroscopy that provide deep insights into the structural variety of these materials. Algal polysaccharides undergo various preparation and modification techniques to enhance their catalytic activity such as immobilization. Homogeneous catalysis, revealing its significance in practical applications like crafting organic compounds and facilitating chemical transformations. Recent studies showcase how algal-derived catalysts prove to be remarkably versatile, showcasing their ability to customise reactions for specific substances. Heterogeneous catalysis, it highlights the significance of immobilization techniques, playing a central role in ensuring stability and the ability to reuse catalysts. The practical applications of heterogeneous algal catalysts in converting biomass and breaking down contaminants, supported by real-life case studies, emphasize their effectiveness. In sustainable chemistry, algal polysaccharides emerge as compelling catalysts, offering a unique intersection of eco-friendliness, structural diversity, and versatile catalytic properties. Tackling challenges such as dealing with complex structural variations, ensuring the stability of the catalyst, and addressing economic considerations calls for out-of-the-box and inventive solutions. Embracing the circular economy mindset not only assures sustainable catalyst design but also promotes efficient recycling practices. The use of algal carbohydrates in catalysis stands out as a source of optimism, paving the way for a future where chemistry aligns seamlessly with nature, guiding us toward a sustainable, eco-friendly, and thriving tomorrow. This review encapsulates-structural insights, catalytic applications, challenges, and future perspectives-invoking a call for collective commitment to catalyze a sustainable scientific revolution.

Regulating the hydroxyl groups reactivity of cellulose by grafting the quaternary ammonium group to achieve a salt-free and low alkali dyeing process for reactive dye

In this work, a salt-free and low alkali dyeing process was developed through cationic modification of cotton fabric with a series of quaternary ammonium salts (QAS). The dyeing performance indicated that the cationic cotton fabric treated with 3-chloro-2-hydroxypropyldimethyloctane ammonium chloride (CT-8) achieved better K/S value (8.87) and dye fixation (90.47 %) compared to the conventional dyeing process. Notably, the CT-8 treated fabric performed exceptionally under salt-free conditions and with a Na2CO3 concentration of 5 g/L. The rationale behind the adoption of a salt-free and low-alkali dyeing process was attributed to the positive charge of quaternary ammonium groups, which had an augmenting impact on the hydroxyl reaction activity of cotton fabrics. The condensed Fukui function, atomic charge, and HOMO orbital calculations showed that the QAS structure could regulate the hydroxyl reactivity of cationic cotton fabric. Our salt-free and low alkali dyeing process not only achieved the aim of reducing chemical consumption and emissions, but also contributed to better understand the effect of hydroxyl reactivity of cationic cotton on the fixation reaction with reactive dye, and provided a new direction to achieve the require of sustainable development and clean production for a variety of industrial crops and products.