Understanding the adsorption behavior of hydrogen and deuterium in nanoporous carbons is critical for advancing gas storage and separation technologies. In this study, neutron scattering, gas adsorption, and molecular simulations were combined to unravel the complex interplay between pore structure, spatial confinement, and adsorption mechanisms. By simulating the adsorption in realistic 3D molecular structures of nanoporous carbons, preferred adsorption sites were identified, revealing that highly confining geometries-rich in defects-enhance adsorption. Denser carbons exhibit stronger confinement but lower overall uptake due to limited pore space. Despite accounting for isotope-specific effects, significant deviations between simulated and experimental scattering data suggest distinct molecular arrangements, particularly for H2. The findings of this study underscore the need for refined atomistic models incorporating surface chemistry and spin-isomer effects to bridge the gap between experiment and simulation, guiding the design of optimized nanoporous materials for hydrogen storage.

Archaeal membranes exhibit remarkable stability under extreme environmental conditions, a feature attributed to their unique lipid composition. While it is widely accepted that tetraether lipids confer structural integrity by forming monolayers, the role of bilayer-forming diether lipids in membrane stability remains unclear. Here, we demonstrate that incorporating diethers into archaeal-like lipid assemblies enhances membrane organization and adaptability under thermal stress. Using neutron diffraction, we show that membranes composed of mixed diethers and tetraethers exhibit greater structural order and stability compared to pure lipid systems. Contrary to expectations, monolayer-forming tetraethers alone display increased variability in lamellar spacing under fluctuating temperature and humidity, whereas mixed lipid membranes maintain a consistent architecture. Furthermore, neutron-scattering length density profiles reveal an unexpected density feature at the bilayer midplane, challenging conventional models of archaeal monolayer organization. These findings suggest that molecular diversity of lipid molecules, rather than tetraether dominance, plays a critical role in membrane auto-assembly, stability, and adaptability. Our results provide new insights into archaeal membrane adaptation strategies, with implications for the development of bioinspired, robust synthetic membranes for industrial and biomedical applications.

The (im)miscibility of hydrocarbons and perfluorocarbons is well known, depends on the chain lengths involved and has been exploited widely in many different areas of chemistry. One area where mixing hydrocarbon- and fluorocarbon-containing moieties is of current interest is in ionic liquids (ILs), where physicochemical properties may be tuned via the preparation of mixtures. Recent work has shown that mixtures of the methylimidazolium ILs [CnMIM][Tf2N] and [CnMIM-F2m+1][Tf2N] (m = n-2) are miscible when a perfluorooctyl chain is used (n = 10), which is unexpected at this chain length. In order to explore the influence of electrostatic attraction between ions in this observed miscibility, related, neutral N-substituted imidazoles CnIm and CnIm-F2m+1 employing hydrocarbon and semiperfluorocarbon chains, and their mixtures, were prepared. The mixtures were miscible at room temperature for n = 8 and immiscible for n = 10. The miscible mixtures were investigated by surface tension, small-angle X-ray and neutron scattering methods and by atomistic molecular dynamics simulations. The data show that while the mixtures [C8Im]1-x[C8Im-F13]x are continuously miscible, some preferential aggregation of alkyl and fluoroalkyl chains is nonetheless present, mirroring the behaviour observed for the IL mixtures [C10MIM]1-x[C10MIM-F17]x[Tf2N], yet in contrast to the shorter-chain mixtures [C8MIM]1-x[C8MIM-F13]x[Tf2N] where no aggregates are seen. As such, it has been possible to draw some conclusions concerning the ability of electrostatic interactions between the ions to suppress the otherwise expected immiscibility of the alkyl and fluoroalkyl chains.

We report a breakthrough strategy for recycling perfluorosulfonic acid (PFSA) polymers, such as Nafion, using tailored ionic liquids (ILs). Imidazolium- and phosphonium-based ILs enabled efficient dispersion of Nafion within 6 h at 180 degrees C, with performance increasing with IL hydrophobicity and alkyl chain length. Two sequential regimes were identified: initial cation exchange followed by IL diffusion enhanced by plasticization, ultimately driving membrane reorganization. Dispersion was triggered once the membrane volume expansion exceeds similar to 180%, underscoring strong IL-polymer affinity. Swelling kinetics deviated from Fickian behavior, indicating complex physicochemical interactions. Ethanol washing and acidification enabled partial IL removal and served as probes for IL localization and binding strength, as confirmed by FTIR. Multiscale structural analyses provide mechanistic insight: small-angle neutron scattering reveals pronounced swelling of ionic domains, while wide-angle X-ray scattering shows IL penetration into amorphous regions with irreversible rearrangements, with crystalline domains remaining preserved. Among the ILs tested, C1C8ImCl and P66614Cl offer the best compromise between dispersion efficiency and extractability. These findings highlight ILs as dual-function agents-both effective PFSA dispersants and potential functional additives-thus enabling high-yield recovery and upcycling of PFSA. This approach opens sustainable, closed-loop pathways for electrochemical energy technologies.

In this paper, we address the formation of highly organized clay tactoids intercalated with a charged polymer (ionene) in an aqueous environment. We report on an original route to achieve such tactoids by starting with preformed clay tactoids, held together by multivalent inorganic atomic ions, as is the case in clay suspensions exchanged with Ca2+ or La3+ ions. Contrary to previously evoked mechanisms of disaggregation-aggregation or successive delamination of individual platelets ("peeling"), we observe clearly a reversible transition between the two types of clay tactoids at an almost constant number of clay nanoplatelets per tactoid. Our observations are based on small-angle X-ray scattering, where a strong correlation peak, called the stacking peak, is an indisputable signature of the stack/tactoid formation and is distinct for the multivalent-ion clay stacks and charged-polymer clay stacks. The initial state of multivalent-ion clay tactoids is essential for the formation of highly organized final charged-polymer clay tactoids. It is as if the preformed multivalent-ion clay tactoids provided a template into which the charged polymer chains get incorporated. Starting from individual delaminated clay layers (Na+ exchanged clays) does not lead to the same final charged-polymer clay stacks. The linear charge density of the polymer chains is another key parameter for the tactoid transition. For weakly charged polymer chains, the transition simply does not take place, even under conditions of a strong excess of the charged polymer. Overall, the final structure of charged-polymer clay stacks strongly depends on the initial structural state of the host clay platelets and the linear charge density of the guest polymer chains.

As part of an ongoing study of the structure and properties of mixtures of ionic liquids in which one component has a hydrocarbon chain and the other a semiperfluorocarbon chain, we now report a study of the mixtures [C8MIM]1-x[C10MIM-F17]x[Tf2N], [C10MIM]1-x[C8MIM-F13]x[Tf2N] and [C10MIM]1-x[C10MIM-F17]x[Tf2N], where [C8MIM][Tf2N] is 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide, [C10MIM][Tf2N] is 1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C8MIM-F13][Tf2N] is 1-(1H,1H,2H,2H-perfluorooctyl)-3-methylimidizolium bis(trifluoromethylsulfonyl)imide and [C10MIM-F17][Tf2N] is 1-(1H,1H,2H,2H-perfluorodecyl)-3-methylimidizolium bis(trifluoromethylsulfonyl)imide. The mixtures were investigated using small-angle X-ray (SAXS) and neutron (SANS) scattering complemented by molecular dynamics simulations (with viscosity and surface tension measurements also possible for the mixtures [C10MIM]1-x[C8MIM-F13]x[Tf2N]). Unlike previous studies of [C8MIM]1-x[C8MIM-F13]x[Tf2N], where no strong evidence of alkyl/fluoroalkyl chain segregation or triphilic behaviour was seen (Elstone et al., J. Phys. Chem. B, 2023, 127, 7394-7407), these new mixtures show the formation of small aggregates of varying sizes of each component, even though all were co-miscible across the full range of compositions. Thus, while a clear polar non-polar peak (PNPP) was observed at large or small values of x, at intermediate compositions the small-angle neutron scattering at low q was dominated by scattering from these small aggregates, while at other compositions, there was little or no evidence of the PNPP. The origins of this behaviour are discussed in terms of inter-chain interactions. The ionic liquids [C10MIM][Tf2N] and [C10MIM-F17][Tf2N] are miscible in all proportions, but scattering studies and MD calculations show the formation of small aggregates. These data are discussed relative to hydrocarbon/fluorocarbon miscibility.

This study reports on the low-pressure hydrogen (H2) and deuterium (D2) physisorption processes in nanoporous activated carbon cloth at supercritical temperatures. In-situ small-angle neutron scattering (SANS) is employed as a hydrogen-sensitive method to determine the pore-size-dependent and isotope-dependent adsorbate densification for different gas pressures up to 1 bar. The changes of the SANS signal resulting from the physisorption of adsorbate molecules in the pore space is described by analytical pore scattering functions resembling slit-like pores. Analysis based on a hierarchical pore model allows quantifying the pore-size-dependent physical density of the confined adsorbate for three pore classes, resembling roughly the IUPAC classes of ultramicropores, supermicropores, and mesopores. While the adsorbate density within the very smallest pores approaches the bulk solid density of H2 for pressures of about 1 bar at 77 K, it remains much lower for larger pores. A high density is also found for D2 within ultramicropores, but these results are hampered by a subtle effect of an exchange of chemically bound hydrogen by deuterium in the sample. These findings contribute to a fundamentally better understanding of confinement effects on hydrogen densification, and affect materials design for efficient hydrogen storage devices working at realistic cryogenic conditions and low pressures.

The stratum corneum (SC) lipid matrix, composed primarily of ceramides (CERs), cholesterol and free fatty acids (FFA), has an important role for the skin barrier function. The presence of the long periodicity phase (LPP), a unique lamellar phase, is characteristic for the SC. Insight into the lipid molecular arrangement within the LPP unit cell is imperative for understanding the relationship between the lipid subclasses and the skin barrier function. In this study, the impact of the CER head group structure on the lipid arrangement and barrier functionality was investigated using lipid models forming the LPP. The results demonstrate that the positions of CER N-(tetracosanoyl)-sphingosine (CER NS) and CER N-(tetracosanoyl)-phytosphingosine (CER NP), two essentials CER subclasses, are not influenced by the addition of another CER subclass (N-(tetracosanoyl)-dihydrosphingosine (CER NdS), N-(2R-hydroxy-tetracosanoyl)-sphingosine (CER AS) or D-(2R-hydroxy-tetracosanoyl)-phytosphingosine (CER AP)). However, differences are observed in the lipid organization and the hydrogen bonding network of the three different models. A similar localization of CER NP and CER NS is also observed in a more complex lipid model, with the CER subclass composition mimicking that of human SC. These studies show the adaptability and insensitivity of the LPP unit cell structure to changes in the lipid head group structures of the CER subclasses.

Lipid membranes are a key component of living systems and have been essential to the origin of life. One hypothesis for the origin of life assumes the existence of protomembranes with ancient lipids formed by Fischer–Tropsch synthesis. We determined the mesophase structure and fluidity of a prototypical decanoic (capric) acid-based system, a fatty acid with a chain length of 10 carbons, and a lipid system consisting of a 1:1 mixture of capric acid with a fatty alcohol of equal chain length (C10 mix). To shed light on the mesophase behavior and fluidity of these prebiotic model membranes, we employed Laurdan fluorescence spectroscopy, which reports on the lipid packing and fluidity of membranes, supplemented by small-angle neutron diffraction data. The data are compared with data of the corresponding phospholipid bilayer systems of the same chain length, 1,2-didecanoyl-sn-glycero-3-phosphocholine (DLPC). We demonstrate that the prebiotic model membranes capric acid and the C10 mix show formation of stable vesicular structures needed for cellular compartmentalization at low temperatures only, typically below 20 °C. They reveal the fluid-like lipid dynamic properties needed for optimal physiological function. High temperatures lead to the destabilization of the lipid vesicles and the formation of micellar structures.

Background Many organisms rely on mineral nutrients taken directly from the soil or aquatic environment, and therefore, developed mechanisms to cope with the limitation of a given essential nutrient. For example, photosynthetic cells have well-defined responses to phosphate limitation, including the replacement of cellular membrane phospholipids with non-phosphorous lipids. Under phosphate starvation, phospholipids in extraplastidial membranes are replaced by betaine lipids in microalgae. In higher plants, the synthesis of betaine lipid is lost, driving plants to other strategies to cope with phosphate starvation where they replace their phospholipids by glycolipids. Results The aim of this work was to evaluate to what extent betaine lipids and PC lipids share physicochemical properties and could substitute for each other. By neutron diffraction experiments and dynamic molecular simulation of two synthetic lipids, the dipalmitoylphosphatidylcholine (DPPC) and the dipalmitoyl-diacylglyceryl-N,N,N-trimethylhomoserine (DP-DGTS), we found that DP-DGTS bilayers are thicker than DPPC bilayers and therefore are more rigid. Furthermore, DP-DGTS bilayers are more repulsive, especially at long range, maybe due to unexpected unscreened electrostatic contribution. Finally, DP-DGTS bilayers could coexist in the gel and fluid phases. Conclusion The different properties and hydration responses of PC and DGTS provide an explanation for the diversity of betaine lipids observed in marine organisms and for their disappearance in seed plants.

Protomembranes at the origin of life were likely composed of short-chain lipids, readily available on the early Earth. Membranes formed by such lipids are less stable and more permeable under extreme conditions, so a novel membrane architecture was suggested to validate the accuracy of this assumption. The model membrane includes the presence of a layer of alkanes in the mid-plane of the protomembrane in between the two monolayer leaflets and lying perpendicular to the lipid acyl chains. Here, we investigated such a possibility experimentally for membranes formed by the short-chain phospholipid 1,2-didecanoyl-sn-glycero-3-phophocholine, including or not the alkanes eicosane, squalane or triacontane by means of neutron membrane diffraction and contrast variation. We found strong indications for incorporation of two of the three alkanes in the membrane mid-plane through the determination of neutron scattering length density profiles with hydrogenated vs deuterated alkanes and membrane swelling at various relative humidities indicating a slightly increased bilayer thickness when the alkanes are incorporated into the bilayers. The selectivity of the incorporation points out the role of the length of the n-alkanes with respect to the capacity of the membrane to incorporate them.

The D16 instrument is a versatile cold-neutron diffractometer at the ILL. It has benefited from a number of upgrades over the years, such as the installation of a large-area 3He Multi-Wire Proportional Chamber (MWPC) in 2011. This detector has provided a resolution of 1 mm x 1 mm over an area of 32 cm x 32 cm. After 12 years of operation, it was replaced by a new curved detector which covers a wider solid angle while maintaining a high angular resolution. Its 86° horizontal angular coverage makes it possible to perform time-resolved experiments with a large q-range. This new detector is based on the Trench-MWPC detector technology developed at the ILL. In the D16 Trench-MWPC, 6 modules are mounted side by side in an 3He-filled curved vessel. Each module consists of 192 cathode blades positioned every 2 mm, and 192 anode wires spaced by 1.5 mm. The radius of curvature of the cathode blades is 1150 mm, providing a parallax-free resolution of 0.075°, horizontally along the 86° angular coverage of the 38 cm high detector. The various steps of the fabrication and mechanical inspection of the D16 Trench-MWPC detector modules and pressure vessel are presented, as well as experimental results obtained during the characterisation of the detector with neutrons.

Phosphate is vital for plant and algae growth, yield, and survival, but in most environments, it is poorly available. To cope with phosphate starvation, photosynthetic organisms used their phospholipids as a phosphate reserve. In microalgae, betaine lipids replace phospholipids whereas, in higher plants, betaine lipid synthesis is lost, driving plants to other strategies. The aim of this work was to evaluate to what extent betaine lipids and PC lipids share physicochemical properties and could thus substitute each other. Using neutron diffraction and molecular dynamics simulations of two synthetic lipids, dipalmitoylphosphatidylcholine (DPPC) and dipalmitoyl-diacylglyceryl-N,N,N-trimethylhomoserine (DP-DGTS), we show that DP-DGTS bilayers are thicker, more rigid, and mutually more repulsive than DPPC bilayers. The different properties and hydration response of PC and DGTS provide an explanation for the diversity of betaine lipids observed in marine organisms and for their disappearance in seed plants. ### Competing Interest Statement The authors have declared no competing interest.

Phosphate is vital for plant and algae growth, yield, and survival, but in most environments, it is poorly available. To cope with phosphate starvation, photosynthetic organisms used their phospholipids as a phosphate reserve. In microalgae, betaine lipids replace phospholipids whereas, in higher plants, betaine lipid synthesis is lost, driving plants to other strategies. The aim of this work was to evaluate to what extent betaine lipids and PC lipids share physicochemical properties and could thus substitute each other. Using neutron diffraction and molecular dynamics simulations of two synthetic lipids, dipalmitoylphosphatidylcholine (DPPC) and dipalmitoyl-diacylglyceryl-N,N,N-trimethylhomoserine (DP-DGTS), we show that DP-DGTS bilayers are thicker, more rigid, and mutually more repulsive than DPPC bilayers. The different properties and hydration response of PC and DGTS provide an explanation for the diversity of betaine lipids observed in marine organisms and for their disappearance in seed plants.

By mixing ionic liquids (ILs), it is possible to fine-tune their bulk and interfacial structure. This alters their physical properties and solvation behavior and is a simple way to prepare a collection of ILs whose properties can be tuned to optimize a specific application. In this study, mixtures of perfluorinated and alkylated ILs have been prepared, and links between composition, properties, and nanostructure have been investigated. These different classes of ILs vary substantially in the flexibility and polarizability of their chains. Thus, a range of useful structural and physical property variations are accessible through mixing that will expand the library of IL mixtures available in an area that to this point has received relatively little attention. In the experiments presented herein, the physical properties and bulk structure of mixtures of 1-methyl-3-octylimidazolium bis(trifluoromethylsulfonyl)imide [C8MIM][Tf2N] and 1-(1H,1H,2H,2H-perfluorooctyl)-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C8MIM-F13][Tf2N] have been prepared. The bulk liquid structure was investigated using a combination of small-angle X-ray and neutron scattering (SAXS and SANS, respectively) experiments in combination with atomistic molecular dynamics simulations and the measurement of density and viscosity. We observed that the addition of [C8MIM-F13][Tf2N] to [C8MIM][Tf2N] causes changes in the nanostructure of the IL mixtures that are dependent on composition so that variation in the characteristic short-range correlations is observed as a function of composition. Thus, while the length scales associated with the apolar regions (polar non-polar peak─PNPP) increase with the proportion of [C8MIM-F13][Tf2N] in the mixtures, perhaps surprisingly given the greater volume of the fluorocarbon chains, the length scale of the charge-ordering peak decreases. Interestingly, consideration of the contact peak shows that its origins are both in the direct anion···cation contact length scale and the nature (and hence volume) of the chains appended to the imidazolium cation.

Archaeal membrane lipids have specific structures that allow Archaea to withstand extreme conditions of temperature and pressure. In order to understand the molecular parameters that govern such resistance, the synthesis of 1,2-di-O-phytanyl-sn-glycero-3-phosphoinositol (DoPhPI), an archaeal lipid derived from myo-inositol, is reported. Benzyl protected myo-inositol was first prepared and then transformed to phosphodiester derivatives using a phosphoramidite based-coupling reaction with archaeol. Aqueous dispersions of DoPhPI alone or mixed with DoPhPC can be extruded and form small unilamellar vesicles, as detected by DLS. Neutron, SAXS, and solid-state NMR demonstrated that the water dispersions could form a lamellar phase at room temperature that then evolves into cubic and hexagonal phases with increasing temperature. Phytanyl chains were also found to impart remarkable and nearly constant dynamics to the bilayer over wide temperature ranges. All these new properties of archaeal lipids are proposed as providers of plasticity and thus means for the archaeal membrane to resist extreme conditions.

Omega-O-acyl ceramides such as 32-linoleoyloxydotriacontanoyl sphingosine (Cer[EOS]) are essential components of the lipid skin barrier, which protects our body from excessive water loss and the penetration of unwanted substances. These ceramides drive the lipid assembly to epidermal-specific long periodicity phase (LPP), structurally much different than conventional lipid bilayers. Here, we synthesized Cer[EOS] with selectively deuterated segments of the ultralong N-acyl chain or deuterated or 13C-labeled linoleic acid and studied their molecular behavior in a skin lipid model. Solid-state 2H NMR data revealed surprising molecular dynamics for the ultralong N-acyl chain of Cer[EOS] with increased isotropic motion toward the isotropic ester-bound linoleate. The sphingosine moiety of Cer[EOS] is also highly mobile at skin temperature, in stark contrast to the other LPP components, N-lignoceroyl sphingosine acyl, lignoceric acid, and cholesterol, which are predominantly rigid. The dynamics of the linoleic chain is quantitatively described by distributions of correlation times and using dynamic detector analysis. These NMR results along with neutron diffraction data suggest an LPP structure with alternating fluid (sphingosine chain-rich), rigid (acyl chain-rich), isotropic (linoleate-rich), rigid (acyl-chain rich), and fluid layers (sphingosine chain-rich). Such an arrangement of the skin barrier lipids with rigid layers separated with two different dynamic "fillings" i) agrees well with ultrastructural data, ii) satisfies the need for simultaneous rigidity (to ensure low permeability) and fluidity (to ensure elasticity, accommodate enzymes, or antimicrobial peptides), and iii) offers a straightforward way to remodel the lamellar body lipids into the final lipid barrier.

Cellular membranes have a remarkable variety of lipids, and different organelles have different lipid compositions. Changes in lipid composition can alter the surface charge, thickness, and fluidity of a membrane characteristics that affect, for example, photosynthesis efficiency or vesicular trafficking. Therefore, for proper organelle function, these parameters must be kept within an appropriate range and must be regulated. Due to their low mobility, plant and algae are dependent on their environment and face sudden changes such as light, temperature or osmotic variations, that will affect membrane features. This review focus on the physical and structural properties of glycerolipids and their impact on membrane specificities in response to environmental cues. Here, we present an overview of the methods that are currently used to establish biophysical membrane properties. We then describe the common glycerolipids present in plants and algae, with their characteristic and their distribution within cell membranes. In the light of the organelle lipid composition, we illustrate how membranes are able to sense and adapt their architecture to maintain their homeostasis and their properties in response to environmental stresses. Thanks to the improved techniques recently available to study membranes in their native context, we are now discovering that the regulation of membrane properties by lipids is far more complex and entangled than it was originally thought.

Amine-based extraction processes are broadly exploited for the selective extraction of uranium from sulfuric leaching liquors. The molecular forces (that is, the enthalpy associated with the multi-scale structuration of tertiary amines) are balanced by entropic effects that have not yet been identified. This first part in a series of reports describes the effects of the alkyl chain configuration on the phase stability and aggregation properties of tertiary amines. It is demonstrated that tertiary amines with longer or slightly branched alkyl chains provide better phase stability and enable constant extraction of uranium. In comparison, more branching of the alkyl chains hinders the formation of a highly curved interfacial layer, thus preventing efficient extraction. Combined small-angle scattering determination of the nanostructures in the organic phase and oil–water surface tension measurements revealed that the alkyl chains effects on the efficiency of the extraction process and phase stability are associated with reverse aggregates with smaller polar core volumes and less co-extracted water, suggesting that packing of the alkyl chains has a direct impact on the extraction efficiency of the solvent extraction system.