There has been much effort to develop sensitive high-energy (X and -ray) polarization detectors recently, with potential applications for a wide variety of fields such as cosmology, particle physics, astrophysics, medical science, material science, and high-energy imaging. However, current technology is constrained both in the energy range and availability due to size, costs, and production difficulties. In this work, we propose a novel mechanism for detecting X-ray polarization that could mitigate these issues. We showed that, when exposed to polarized X-rays, aligned gold nanorods lead to an anisotropic response, which can be explored in the reconstruction of the polarization of the incident X-rays. The differences in the scattered X-ray directions can be used in the development of a novel detector. These would be on a much smaller scale, more cost-effective, and much easier to manufacture compared to current and proposed options.

Hypothesis The friction and interfacial nanostructure of a water-in-surface-active ionic liquid mixture, 1.6 M 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate ([BMIm][AOT]), can be tuned by applying potential on Au(1 1 1) and stainless steel. Experimental Atomic force microscopy (AFM) was used to examine the friction and interfacial nanostructure of 1.6 M [BMIm][AOT] on Au(1 1 1) and stainless steel at different potentials. Findings Superlubricity (vanishing friction) is observed for both surfaces at OCP+1.0 V up to a surface-dependent critical normal force due to [AOT](-) bilayers adsorbing strongly to the positively charged surface thus allowing AFM tip to slide over solution-facing hydrated anion charged groups. High-resolution AFM imaging reveals ripple-like features within near-surface layers, with the smallest amplitudes at OCP+1 V, indicating the highest structural stability and resistance to thermal fluctuations due to highly ordered boundary [AOT](-) bilayers templating robust near-surface layers. Exceeding the critical normal force at OCP+1.0 V causes the AFM tip to penetrate the hydrated [AOT](-) layer and slide over alkyl chains, increasing friction. At OCP and OCP-1.0 V, higher friction correlates with more pronounced ripples, attributed to the rougher templating [BMIm](+) boundary layer. Kinetic experiments show that switching from OCP-1.0 V to OCP+1.0 V achieves superlubricity within 15 s, enabling real-time friction control.

Lyotropic liquid crystal gels of phytantriol and monoolein are well known examples of self-assembled systems in water, which have multiple applications across biomedical and materials science. However aqueous systems can be restricted by rapid solvent evaporation, and the limited solubility of some species in water. Here we explore the formation of liquid crystalline phases of phytantriol and monoolein in mixtures of water with two protic ionic liquids, ethylammonium nitrate (EAN) and ethanolammonium nitrate (EtAN), and three deep eutectic solvents (DES) formed from mixtures of choline chloride with urea, fructose or citric acid. The structures of the gel phase in excess solvent were measured using small angle X-ray scattering for a fixed lipid concentration (5% w/w) as a function of temperature. The phase diagrams of both lipids in DES-water mixtures and the non-amphiphilic ionic liquid, EtAN, indicate that higher negative curvature inverse hexagonal structures are favoured by addition of water. However, the amphiphilic ionic liquid EAN swells and stabilises the cubic Pn3m structure. The interplay of solvent structure, polarity and molecular size are key to understanding the formation and stability of lyotropic liquid crystalline gels in these systems.

The encapsulation of liquid crystalline phases, formed from biocompatible amphiphiles, into nanoparticles has emerged as a promising delivery strategy for hydrophilic and hydrophobic therapeutics. Strategies to characterize these delivery systems as a function of formulation parameters and aqueous environment post-manufacture are well-documented. A critical gap remains regarding the assembly kinetics and in situ dynamics of these systems using industrially relevant manufacturing techniques. Systematically investigating these characteristics is challenging: computational simulations are time-intensive and costly, while current in situ quantification techniques are limited in scalability and batch size. We here combine synchrotron small-angle X-ray scattering with Flash NanoPrecipitation, a scalable turbulent mixing technology, to capture time-resolved measurements of the formation of liquid crystal phases under nanoconfinement during and after nanoprecipitation. This technique reveals that self-assembly occurs in two steps, with internal liquid crystal self-assembly occurring on longer time scales (seconds to minutes) than initial nanoprecipitation (milliseconds) as a function of formulation parameters.

HYPOTHESIS:Diluting the surface-active ionic liquid 1-butyl-3-methylimidazolium 1,4-bis-2-ethylhexylsulfosuccinate (BMIM AOT) with the non-solvating diluent 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (TFTFE) will reduce viscosity while preserving essential nanostructures and electrochemical properties, creating locally concentrated ionic liquids (LCILs) suitable for energy storage applications. EXPERIMENTS:BMIM AOT:TFTFE mixtures at 2:1, 1:1, and 1:2 weight ratios were investigated using rheological measurements, conductivity analysis, cyclic voltammetry, electrochemical impedance spectroscopy, small- and wide-angle X-ray scattering (S/WAXS), and atomic force microscopy (AFM). FINDINGS:TFTFE addition at 1:1 weight ratio reduced BMIM AOT viscosity by 99 % and increased conductivity by over one order of magnitude while maintaining electrochemical stability (>4 V). S/WAXS revealed preservation of characteristic sponge-like nanostructures in the bulk for all BMIM AOT:TFTFE mixtures investigated. Differential capacitance measurements showed enhanced charge storage capabilities, with maximum performance at 1:1 ratio due to improved ion mobility. AFM showed that TFTFE enhances solvophobic segregation at neutral interfaces but reduces interfacial nanostructures at charged surfaces. These findings reveal that SAIL-based LCILs achieve optimal balance between low viscosity and stable nanostructures, making them promising electrolytes for energy storage devices requiring fast charge-discharge rates and electrochemical stability.

Self-assembly of amphiphilic molecules can take place in extremely concentrated salt solutions, such as inorganic molten salt hydrates or hydrous melts. The intermolecular interactions governing the organization of amphiphilic molecules under such extreme conditions are not yet fully understood. In this study, we investigated the specific effects of ions on the self-assembly of the non-ionic surfactant C12H25(OCH2CH2)10OH (C12E10) under extreme salt concentrations, using calcium nitrate tetrahydrate as a reference. The mixtures of Ca(NO3)2·4H2O and C12E10 displayed lyotropic (H1 and I1) and micellar phases, in contrast to CaCl2·xH2O-C12E10 or CaBr2·xH2O-C12E10 mixtures where mesostructurally ordered salt-surfactant complexes were observed. The Ca(NO3)2·4H2O-C12E10 system was thoroughly investigated by constructing its binary phase diagram and performing thermal and spectral comparisons with other salt hydrates. The Ca(NO3)2 system displayed significantly higher isotropization temperatures than zinc, aluminium, and lithium nitrate systems. ATR-FTIR analysis revealed that Ca2+ primarily interacts with the surfactant head groups through ion-dipole interactions, while these interactions were less pronounced with other cations. The results show that an intermediate hydration/coordination energy of the metal ion can lead to stronger metal-surfactant interactions and thermally more stable liquid crystals. Comparison between the Ca(NO3)2, CaCl2, and CaBr2 systems suggests that reduced ion pair formation enhances the interactions between Ca2+ and oxyethylene groups, leading to the salting-out of salt-surfactant complexes. Despite its low water content and strong intermolecular interactions, the Ca(NO3)2·xH2O-C12E10 system exhibited an electrical conductivity of up to 1.0 × 10-3 S cm-1 with 4 water molecules per salt, making it a promising medium for electrochemical applications.

HYPOTHESIS:Water-in-salt electrolytes (WiSEs) are safer alternatives to organic electrolytes in lithium-ion batteries. While surfactants have been proposed as performance enhancing additives, their self-assembly behaviour in these concentrated systems is completely unknown. We hypothesise that ionic surfactants can form micelles in WiSEs with their structure dependent on salt type, salt-to-surfactant ratio, and temperature. EXPERIMENTS:The self-assembly of dodecyltrimethylammonium bromide (DTAB) in various WiSEs was investigated using small-angle neutron scattering. We examined systems containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium nitrate (LiNO3), or sodium nitrate (NaNO3) across various salt-to-surfactant ratios and temperatures (25-80 °C). FINDINGS:The surfactant DTAB forms micelles in all WiSEs studied, persisting at salt concentrations far beyond those in conventional aqueous solutions. In LiTFSI WiSEs, salt concentration determines micelle structure. Hydrophobic TFSI- counterions screen the micelle surface at 5 mol/kg, forming elongated micelles, while at ≥8 mol/kg they intercalate between headgroups, producing globular micelles. At certain high salt/low surfactant compositions, traditional micelles do not form. Instead, small, disordered clusters are formed that are further enhanced at elevated temperatures. In contrast, hydrophilic NO3- counterions (LiNO3 and NaNO3 systems) maintain near identical morphologies regardless of salt concentration, though co-ion type strongly affects morphology. Na+ produces well-defined wormlike micelles while Li+ causes instability, resulting in highly polydisperse assemblies. These findings provide a platform for enhancing WiSEs through protective electrode interfaces that further reduce water activity, inhibit lithium dendrite formation, and control ion transport. This work also advances fundamental understanding of surfactant self-assembly in concentrated electrolytes and in nanostructured fluids.

Neutron diffraction with empirical potential structure refinement was used to investigate the bulk liquid nanostructure of mixtures of choline arginate (Ch[Arg]), choline lysinate (Ch[Lys]), and water at mole ratios of 1Ch[Arg]:1Ch[Lys]:6H2O (balanced), 1Ch[Arg]:1Ch[Lys]:20H2O (balanced dilute), 3Ch[Arg]:1Ch[Lys]:12H2O (Arg- rich), and 1Ch[Arg]:3Ch[Lys]:12H2O (Lys- rich). The Arg- and Lys- anions tend not to associate due to electrostatic repulsion between charge groups and weak anion-anion attractions. This means that the local ion structures around the anions in these mixtures resemble the parent single-component systems. The bulk liquid nanostructure varies with the Arg-:Lys- ratio. In the Lys--rich mixture (1Ch[Arg]:3Ch[Lys]:12H2O), Lys- side chains cluster into a continuous apolar domain separated from a charged domain of polar groups. In the balanced mixture (1Ch[Arg]:1Ch[Lys]:6H2O), Lys- side chains form discrete apolar aggregates within a continuous polar domain of Arg-, Ch+, and water, and in the Arg--rich mixture (3Ch[Arg]:1Ch[Lys]:12H2O), the distribution of Lys- and Arg- is nearly homogeneous. Finally, in the balance dilute system (1Ch[Arg]:1Ch[Lys]:20H2O), a percolating water domain forms.

HYPOTHESIS:The self-assembly structures and phase behaviour of phospholipids in protic ionic liquids (ILs) depend on intermolecular forces that can be controlled through changes in the size, polarity, and H-bond capacity of the solvent.EXPERIMENTS:The structure and temperature stability of the self-assembled phases formed by four phospholipids in three ILs was determined by a combination of small- and wide-angle X-ray scattering (SAXS and WAXS) and small-angle neutron scattering (SANS). The phospholipids have identical phosphocholine head groups but different alkyl tail lengths and saturations (DOPC, POPC, DPPC and DSPC), while the ILs' amphiphilicity, H-bond network density and polarity are varied between propylammonium nitrate (PAN) to ethylammonium nitrate (EAN) to ethanolammonium nitrate (EtAN).FINDINGS:The observed structures and phase behaviour of the lipids becomes more surfactant-like with decreasing average solvent polarity, H-bond network density and surface tension. In PAN, all the investigated phospholipids behave like surfactants in water. In EAN they exhibit anomalous phase sequences and unexpected transitions as a function of temperature, while EtAN supports structures that share characteristics with water and EAN. Structures formed are also sensitive to proximity to the lipid chain melting temperature.

Atomic force microscope (AFM) videos reveal the near-surface nanostructure and dynamics of the ionic liquids (ILs) 1-butyl-3-methylimidazolium dicyanamide (BMIM DCA) and 1-hexyl-3-methylimidazolium dicyanamide (HMIM DCA) above highly oriented pyrolytic graphite (HOPG) electrodes as a function of surface potential. Molecular dynamics (MD) simulations reveal the molecular-level composition of the nanostructures. In combination, AFM and MD show that the near-surface aggregates form via solvophobic association of the cation alkyl chains at the electrode interface. The diffusion coefficients of interfacial nanostructures are approximate to 0.01 nm2 s-1 and vary with the cation alkyl chain length and the surface potential. For each IL, the nanostructure diffusion coefficients are similar at open-circuit potential (OCP) and OCP + 1V, but BMIM DCA moves about twice as fast as HMIM DCA. At negative potentials, the diffusion coefficient decreases for BMIM DCA and increases for HMIM DCA. When the surface potential is switched from negative to positive, a sudden change in the direction of the nanostructure motion is observed for both BMIM DCA and HMIM DCA. No transient dynamics are noted following other potential jumps. This study provides a new fundamental understanding regarding the dynamics of electrochemically stable ILs at electrodes vital for the rational development of IL-based electrochemical devices. Atomic force microscope (AFM) videos and molecular dynamics (MD) simulations are used to reveal the structure and dynamics of the aggregates of two electrochemically relevant aprotic ionic liquids, 1-butyl-3-methylimidazolium dicyanamide (BMIM DCA) and 1-hexyl-3-methylimidazolium dicyanamide (HMIM DCA), near a graphite electrode, as a function of potential. image

Video-rate atomic force microscopy (AFM) is used to record the near-surface nanostructure and dynamics of one pure ionic liquid (IL), 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate (HMIM FAP), and a locally-concentrated IL comprising HMIM FAP with the low viscosity diluent 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether (TFTFE), on highly oriented pyrolytic graphite (HOPG) and Au(111) electrodes as a function of potential. Over the potential range measured (open-circuit potential +/- 1 V), different near-surface nanostructures are observed. For pure HMIM FAP, globular aggregates align in rows on HOPG, whereas elongated and worm-like nanostructures form on Au(111). For 2:1 (wt:wt) HMIM FAP:TFTFE, larger and less defined diluent swollen IL aggregates are present on both electrodes. Long-lived near-surface nanostructures for HMIM FAP and the 2:1 (wt:wt) HMIM FAP:TFTFE persist on both electrodes. 2:1 (wt:wt) HMIM FAP:TFTFE mixture diffuses more rapidly than pure HMIM FAP on both electrodes with obviously higher diffusion coefficients on HOPG than on Au(111) due to weaker electrostatic and solvophobic interactions between near-surface aggregates and Stern layer ions. These outcomes provide valuable insights for a wide range of IL applications in interface sciences, including electrolytes, catalysts, lubricants, and sensors. Video-rate atomic force microscopy reveals distinct, persistent near-surface nanostructures of a locally-concentrated ionic liquid on highly oriented pyrolytic graphite (HOPG) and Au(111) electrodes at various potentials. The locally-concentrated ionic liquid more rapidly than the pure ionic liquid, with higher diffusion coefficients on HOPG attributed to weaker interactions between near-surface aggregates and Stern layer ions. These insights have implications for ionic liquid applications in interfacial sciences. image

Nanofibers synthesized by PISA-RAFT and added into pigmented commercial paint improve stain resistance, extensibility and toughness.

Colloidal systems and soft materials are well suited to neutron scattering, and the community has readily adopted elastic scattering techniques to investigate their structure. Due to their unique properties, neutrons may also be used to characterize the dynamics of soft materials over a wide range of length and time scales in situ. Both static structures and an understanding of how molecules move about their equilibrium positions is essential if we are to deliver on the promise of rationally designing soft materials. In this review we introduce the basics of neutron spectroscopy and explore the ways in which inelastic neutron scattering can be used to study colloidal and soft materials. Illustrative examples are chosen that highlight the phenomena suitable for investigation using this suite of techniques.

Video-rate atomic force microscopy (AFM) is used to study the near-surface nanostructure dynamics of the ionic liquid ethylammonium nitrate (EAN) at a highly oriented pyrolytic graphite (HOPG) electrode as a function of potential in real-time for the first time. The effects of varying the surface potential and adding 10 wt% water on the nanostructure diffusion coefficient are probed. For both EAN and the 90 wt% EAN-water mixture, disk-like features ≈9 nm in diameter and 1 nm in height form above the Stern layer at all potentials. The nanostructure diffusion coefficient increases with potential (from OCP -0.5 V to OCP +0.5 V) and with added water. Nanostructure dynamics depends on both the magnitude and direction of the potential change. Upon switching the potential from OCP -0.5 V to OCP +0.5 V, a substantial increase in the diffusion coefficients is observed, likely due to the absence of solvophobic interactions between the nitrate (NO3 - ) anions and the ethylammonium (EA+ ) cations in the near-surface region. When the potential is reversed, EA+ is attracted to the Stern layer to replace NO3 - , but its movement is hindered by solvophobic attractions. The outcomes will aid applications, including electrochemical devices, catalysts, and lubricants.

Partial substitution of ethylene oxide with carbon dioxide moieties can yield greener nonionic surfactants with comparable functionalities. In water, studies showed that the incorporation of CO2 moieties suppresses the formation of liquid crystalline phases at high concentrations. A similar reduction in solvation and suppression of liquid crystal formation is observed here in the ionic liquids ethylammonium nitrate and propylammonium nitrate. Small-angle neutron scattering is used to study the solvation and packing of micelles in ionic liquids as functions of temperature, concentration, and content of CO2 moieties. By comparing with aqueous solutions, this work shows that while the nature of surfactant-solvent interaction is comparable among water and alkylammonium nitrate ILs, their behaviours in the solvated micelle shell are different. The lack of liquid crystalline phases should be attributed to the small excluded volume of micelles, which can be fine-tuned via ion design and choice of solvent.

The physical properties of ionic liquids (ILs) have led to intense research interest, but for many applications, high viscosity is problematic. Mixing the IL with a diluent that lowers viscosity offers a solution if the favorable IL physical properties are not compromised. Here we show that mixing an IL or IL electrolyte (ILE, an IL with dissolved metal ions) with a nonsolvating fluorous diluent produces a low viscosity mixture in which the local ion arrangements, and therefore key physical properties, are retained or enhanced. The locally concentrated ionic liquids (LCILs) examined are 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (HMIM TFSI), 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate (HMIM FAP), or 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate (BMIM FAP) mixed with 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether (TFTFE) at 2:1, 1:1, and 1:2 (w/w) IL:TFTFE, as well as the locally concentrated ILEs (LCILEs) formed from 2:1 (w/w) HMIM TFSI-TFTFE with 0.25, 0.5, and 0.75 m lithium bis(trifluoromethylsulfonyl)imide (LiTFSI). Rheology and conductivity measurements reveal that the added TFTFE significantly reduces viscosity and increases ionic conductivity, and cyclic voltammetry (CV) reveals minimal reductions in electrochemical windows on gold and carbon electrodes. This is explained by the small- and wide-angle X-ray scattering (S/WAXS) and atomic force microscopy (AFM) data, which show that the local ion nanostructures are largely retained in LCILs and LCILEs in bulk and at gold and graphite electrodes for all potentials investigated.

Neutron diffraction with empirical potential structure refinement (EPSR) show the deep eutectic solvent (DES) 1 : 4 choline chloride : butyric acid is amphiphilically nanostructured. Nanostructure results from solvophobic interactions between the alkyl chains of the butyric acid hydrogen bond donor (HBD) and is retained with addition of 10 wt% water. EPSR fits to the diffraction data is used to produce a three-dimensional model of the liquid which is interrogated to reveal the interactions leading to the solvophobic effect, and therefore nanostructure, in this DES at atomic resolution. The model shows electrostatic and hydrogen bond interactions cause the cation, anion and HBD acid group to cluster into a polar domain, from which the acid alkyl chains are solvophobically excluded into theapolar domain. The polar and apolar domains percolate through the liquid in a bicontinuous sponge-like structure. The effect of adding 10 wt% water is probed, revealing that water molecules are sequestered around the cation and anion within the polar domain, while the neat bulk structure is retained. Alkyl chain packing in the apolar domain becomes slightly better-defined indicating water marginally strengthens solvophobic segregation. These findings reveal bulk self-assembled nanostructure can be produced in DESs via an amphiphilic HBD.