Descriptors link basic physicochemical parameters that characterize the materials and the environment to the catalytic performance. Traditionally, descriptors are rooted in mechanistic understanding of elementary surface reactions gained from surface...

The equilibrium between hydrated and hydrolysed forms of CO2 in water is central to a multitude of processes in geology, oceanography and biology. Chemistry of the carbonate system is well...

Prof. Marc Hillmyer receiving the Spiers Memorial medal from Prof. Susan Perkin during the meeting on Polymerisation and depolymerisation chemistry: the second century Faraday Discussion .

Few areas of materials science have evolved as rapidly and dynamically as high-entropy alloys (HEAs). What began just two decades ago as a bold idea - first articulated by Brian Cantor and Jien-Wei Yeh - that chemical complexity itself could stabilise materials, has grown into a thriving research field spanning structural, functional, and catalytic applications. The Faraday Discussions 'High-entropy alloy nanostructures: from theory to application', held at the Royal Society of Chemistry in London, brought together researchers from across the world to examine a fundamental question at the heart of this concept: with multicomponent alloys now within reach, do they truly deliver beyond simpler systems, or does complexity risk obscuring purpose?

High-entropy alloys (HEAs) combine five or more elements in near-equiatomic ratios, opening an immense compositional space whose optical behaviour is still largely unknown. Phase-modulated ellipsometry on bulk CrMnFeCoNi (Cantor) shows that its intrinsic optical constants, n, k, ε1 and ε2, deviate strongly from the arithmetic means of the constituent elements-by up to a factor of two beyond 1 μm-yet the derived functional responses, reflectance R and absorption coefficient α, are reproduced to within ∼20%. Cantor nanoparticles have been produced by nanosecond electric discharges in liquid nitrogen. Dark-field spectroscopy and Mie calculations reveal a dominant scattering mode near 100 nm that red-shifts and broadens with increasing size; the steady-state photothermal rise calculated from the absorption cross-section σabs falls between those of the constituent pure metals. Generalising the averaging rule, we compute proxy values of R and α for 10 994 density-functional-theory-predicted HEAs. Successive optical, thermal and resource filters condense the space to 58 candidates at 355 nm and eight refractory alloys at 1064 nm, illustrating a "sustainable-by-design" route for future HEA photonics.

In this study, epoxidized lignins were prepared by reacting softwood (SW) and hardwood (HW) technical (kraft) lignins with a biobased epichlorohydrin. The chemical structures, rheological behaviors, and thermomechanical properties of the epoxidized lignins were measured and compared with those of petroleum-based (DGEBA) epoxy resin. First, the chemical and physical properties of the lignin samples were assessed using Fourier-transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), quantitative phosphorus nuclear magnetic resonance spectroscopy (31P NMR), and 2D-heteronuclear single quantum coherence (HSQC) NMR analyses. Subsequently, the unmodified lignins were epoxidized over a short period (3 hours), using ethyl lactate as a biobased co-solvent. The 31P NMR and HSQC analysis of the epoxidized lignins confirmed that phenolic hydroxyl and carboxylic acid groups in lignin were selectively epoxidized without any other significant changes to the chemical structure of lignin. Rheological multi-wave curing studies of both lignin-based and bisphenol A-based (DGEBA) resins cured with a biobased curing agent revealed that the lignin-based systems exhibited significantly shorter gelation times and lower activation energies. Further analyses, including gel fraction, swelling ratio, thermal gravimetric analysis (TGA), and dynamic mechanical analysis (DMA) results, demonstrated that lignin-based thermosets had comparable properties to the petroleum-based epoxy system when both were prepared with solvent (40 wt%) inclusion. Notably, the thermoset resin made with kraft hardwood lignin exhibited superior thermomechanical properties compared to the softwood system.

Two technical lignins, a softwood kraft lignin (SKL) and a wheat straw organosolv lignin (WSOSL) were fractionated using a Soxhlet extractor that was connected to a piston pump for solvent movement such that Soxhlet extraction using non-azeotropic solvent mixtures was feasible. Fractionation of the lignins using such solvent mixtures that could be tuned in terms of hydrogen-bond acceptor and donor characteristics and polarities yielded novel fractions not accessible in standard Soxhlet-based fractionations. Two SKL fractions could be obtained applying aqueous acetone that displayed homogeneous structural characteristics while differing significantly in molecular weights. WSOSL could be gradually purified, allowing for the generation of a rather pure lignin carbohydrate complex (LCC) fraction and a purified high molecular weight lignin fraction.

This article addresses current challenges in lignin chemistry by exploring four thematic areas. We begin by examining the major chemical transformations that occur in lignin and discuss the emerging structural understanding of technical lignins. The discussion then shifts to lignin fractionation strategies, which are essential for reducing its inherent heterogeneity and complexity, thereby enabling its use in practical applications. Next, we delve into the chemical and physical behavior of lignin in solution, with particular emphasis on its self-assembly processes relevant to nanoparticle formation. The supramolecular interactions driving these assemblies - such as π-π stacking, hydrogen bonding, and solvent polarity - are analyzed to identify key parameters for designing lignin-based nanomaterials. These materials show promising applications across sectors including agriculture, packaging, cosmetics, and pharmaceuticals. We then consider the broader valorization of lignin, focusing on the rheological and antioxidant properties of lignin fractions. Particular attention is given to their role in forming polymer blends with polyethylene, highlighting their influence on thermal stability and mechanical performance. Finally, we explore lignin's potential as a non-petroleum precursor for carbon fiber production. We critically assess the main barriers in this field, such as lignin's relatively low molecular weight and thermal behavior, which hinder effective fiber formation and graphitization. Strategies to address these challenges, including the integration of fractionation techniques with chemical modifications, are discussed. The article concludes with a review of recent efforts to overcome the limitations of lignin graphitization and enhance its viability as a sustainable carbon fiber source.