Small- And Wide-angle X-ray Scattering Research Articles

Controlling the formation of ionic complex vesicles through double-tailed surfactants.

Liposomes are often used in cosmetics since they are naturally derived and have excellent texture enhancing capabilities. However, when preparing them by using phospholipids with unsaturated acyl groups, they easily suffer from oxidative degradation. Accordingly, hydrogenated phospholipids are preferred, however, it is difficult to prepare stable liposomes due to its high gel-liquid crystalline phase transition temperature. On the other hand, although dialkyl dimethyl ammonium type cationic surfactants are widely known to form vesicles, they have rarely been used for skincare products except for water-in-oil type emulsion creams stabilized by organically modified clay minerals. We decided to overcome all of the problems above through ionic complex vesicles formed by double-tailed cationic and anionic surfactants. Distearyl dimethyl ammonium chloride (DSAC) and sodium dilauramidoglutamide lysine (DLGL) were selected as cationic and anionic surfactants, respectively. Differential scanning calorimetry (DSC) and small- and wide-angle X-ray scattering (SWAXS) measurements were performed to confirm the DSAC/DLGL/water ternary phase diagram. Newly developed ionic complex vesicle formation was confirmed by cryogenic transmission electron microscopy (cryo-TEM). The adsorbed cosmetic film structure on the skin invivo was evaluated through the polarized infrared external reflection (PIR-ER). Finally, a cosmetic lotion formula was developed and the vesicle size was determined by dynamic light scattering (DLS). DSC and SWAXS data indicated that stable vesicles could be obtained at a molar ratio of DLGL to DSAC = 6:4. At this molar ratio, multi lamellar vesicles with diameters less than 100 nm were observed through cryo-TEM. PIR-ER data revealed that the developed vesicles formed a highly perpendicular orientation to the human skin surface. We have succeeded in formulating a cosmetic lotion containing developed vesicles with a mean diameter of 63.2 nm, which was stable over 1 month at 0, 37, and 50°C. Our newly developed vesicles can be easily obtained through a coagulation process. Also, the adsorbed film structure supported by PIR-ER experiments implies that the developed lotion has an excellent texture that is the same as cosmetic lotions containing liposomes. Therefore, it's possible that this ionic complex vesicle could take the place of liposomes.

Low-temperature and high-pressure phase transitions of ionic liquid 1-decyl-3-methylimidazolium bromide

The phase behavior of an ionic liquid (IL) was investigated at low temperature (LT) and high pressure (HP). The utilized IL was 1-decyl-3-methylimidazolium bromide ([C10mim][Br]), whose cation possesses a long alkyl side-chain. The LT- and HP-crystal polymorphs of [C10mim][Br] were observed conducting small- and wide-angle X-ray scattering (SWAXS) experiments. Upon cooling, a liquid crystal was formed, which subsequently transformed into crystalline species with the modulated layered structure possessing the double Bragg reflection. In addition to the layered structure, the hybrid layered structure coexisted upon heating. At HP, 00ℓ Bragg reflections representing the layered structure were not observed in SWAXS patterns. The HP-crystal phase of [C10mim][Br] was characterized by double Bragg reflection in the low scattering wavevector region. The non-layered HP-crystal caused the large bulk modulus.

Hierarchical Emulsion Structure and Functionality Regulated by Coexisting Bicontinuous Microemulsion and Liquid Crystal Domains.

Since microemulsions are usually low viscosity fluids, enhanced rheological properties while maintaining their structure-derived functionality have long been desired from an industrial application point of view. However, for instance, it is practically difficult to thicken bicontinuous microemulsions (BCMEs) without perturbing their alternating domain structure or to emulsify oils using BCME having ultralow interfacial tension as an external phase. In this study, a methodology called a BCLC emulsification technique has been constructed to obtain oil-in-water emulsions stabilized by coexisting BCME and liquid crystal (LC) phases. The produced emulsions based on polyglyceryl-10 diisostearate, polyglyceryl-6 dicaprate, cetyl ethylhexanoate, and water are structurally scrutinized by means of small- and wide-angle X-ray scattering (SWAXS), freeze fracture transmission electron microscopy (FF-TEM), and scanning electron assisted dielectric microscopy (SE-ADM). The data provide experimental evidence that this methodology enables one to control the bending elasticity of the interfacial membranes and consequent long-range order of the BCME domains. Moreover, closely correlated with the interfacial membrane properties, submicrometer-sized fine oil droplets are supported by the LC networks and agglomerated into spongy or network-like phase-separation patterns. The resulting nonfluidic, jelly emulsions are particularly useful in cosmetics because of combined BCME-derived high cleansing performance and excellent usability owing to the enhanced viscosity. The thickening mechanisms are essentially different from those of common lamellar-gel-stabilized oil-in-water emulsions, which utilize crystalline lamellar gel networks as oil droplet stabilizers.

Comprehensive characterization of polyproline tri-helix macrocyclic nanoscaffolds for predictive ligand positioning.

Multivalent ligands hold promise for enhancing avidity and selectivity to simultaneously target multimeric proteins, as well as potentially modulating receptor signaling in pharmaceutical applications. Essential for these manipulations are nanosized scaffolds that precisely control ligand display patterns, which can be achieved by using polyproline oligo-helix macrocyclic nanoscaffolds via selective binding to protein oligomers and cell surface receptors. This work focuses on synthesis and structural characterization of different-sized polyproline tri-helix macrocyclic (PP3M) scaffolds. Through combined analysis of circular dichroism (CD), small- and wide-angle X-ray scattering (SWAXS), electron spin resonance (ESR) spectroscopy, and molecular modeling, a non-coplanar tri-helix loop structure with partially crossover helix ends is elucidated. This structural model aligns well with scanning tunneling microscopy (STM) imaging. The present work enhances the precision of nanoscale organic synthesis, offering prospects for controlled ligand positioning on scaffolds. This advancement paves the way for further applications in nanomedicine through selective protein interaction, manipulation of cell surface receptor functions, and developments of more complex polyproline-based nanostructures.

Unraveling the Structure-Property-Performance Relationships of Fused-Ring Nonfullerene Acceptors: Toward a C-Shaped ortho-Benzodipyrrole-Based Acceptor for Highly Efficient Organic Photovoltaics.

The high-performance Y6-based nonfullerene acceptors (NFAs) feature a C-shaped A-DA'D-A-type molecular architecture with a central electron-deficient thiadiazole (Tz) A' unit. In this work, we designed and synthesized a new A-D-A-type NFA, termed CB16, having a C-shaped ortho-benzodipyrrole-based skeleton of Y6 but with the Tz unit eliminated. When processed with nonhalogenated xylene without using any additives, the binary PM6:CB16 devices display a remarkable power conversion efficiency (PCE) of 18.32% with a high open-circuit voltage (Voc) of 0.92 V, surpassing the performance of the corresponding Y6-based devices. In contrast, similarly synthesized SB16, featuring an S-shaped para-benzodipyrrole-based skeleton, yields a low PCE of 0.15% due to the strong side-chain aggregation of SB16. The C-shaped A-DNBND-A skeleton in CB16 and the Y6-series NFAs constitutes the essential structural foundation for achieving exceptional device performance. The central Tz moiety or other A' units can be employed to finely adjust intermolecular interactions. The single-crystal X-ray structure reveals that ortho-benzodipyrrole-embedded A-DNBND-A plays an important role in the formation of a 3D elliptical network packing for efficient charge transport. Solution structures of the PM6:NFAs detected by small- and wide-angle X-ray scattering (SWAXS) indicate that removing the Tz unit in the C-shaped skeleton could reduce the self-packing of CB16, thereby enhancing the complexing and networking with PM6 in the spin-coating solution and the subsequent device film. Elucidating the structure-property-performance relationships of A-DA'D-A-type NFAs in this work paves the way for the future development of structurally simplified A-D-A-type NFAs.

Fitting high-resolution electron density maps from atomic models to solution scattering data

Solution scattering techniques, such as small- and wide-angle X-ray scattering (SWAXS), provide valuable insights into the structure and dynamics of biological macromolecules in solution. In this study, we present an approach to accurately predict solution X-ray scattering profiles at wide angles from atomic models by generating high-resolution electron density maps. Our method accounts for the excluded volume of bulk solvent by calculating unique adjusted atomic volumes directly from the atomic coordinates. This approach eliminates the need for one of the free fitting parameters commonly used in existing algorithms, resulting in improved accuracy of the calculated SWAXS profile. An implicit model of the hydration shell is generated that uses the form factor of water. Two parameters, namely the bulk solvent density and the mean hydration shell contrast, are adjusted to best fit the data. Results using eight publicly available SWAXS profiles show high-quality fits to the data. In each case, the optimized parameter values show small adjustments demonstrating that the default values are close to the true solution. Disabling parameter optimization produces significantly more accurate predicted scattering profiles compared to the leading software. The algorithm is computationally efficient, comparable to the leading software and up to 10 times faster for large molecules. The algorithm is encoded in a command line script called denss.pdb2mrc.py and is available open source as part of the DENSS v1.7.0 software package. In addition to improving the ability to compare atomic models to experimental SWAXS data, these developments pave the way for increasing the accuracy of modeling algorithms using SWAXS data and decreasing the risk of overfitting.

Three Phases of Basic Zirconium and Hafnium Hydroxohalides.

Aqueous solutions of zirconium and hafnium (M) halides (X) with atomic ratios α = X/M near 1 form glasses on evaporation. Herein, we describe the preparation and properties of these glasses and discuss the nature of the crystal-glass equilibria beyond the pure glass compositions. Small- and wide-angle X-ray scattering (SWAXS) studies reveal increased polymerization as α decreases from 2 to 1. The glasses are found to be much denser than their crystalline counterparts. Crystals forming in contact with glasses retain the well-known Zr-tetrameric hydroxo cluster unit with hydroxide compensating for the lowered halide content. We find that the chemical formulas for all of the solid hydroxohalides may be described by the single parameter α, according to the formula M(OH)4-αXα·(4α - 1)H2O. This description is valid for the crystalline chloride (MOX2·8H2O = M(OH)2X2·7H2O), the glassy solids with α < 2, and hydrolyzed products (α ≈ 0.5). The water content is also determined by α with hydroxide-hydrogen bonding replacing halide-hydrogen bonding as α decreases. A Eu3+-doped Zr,Cl glass exhibits photoluminescence transitions 5D0 → 7Fn (n = 1, 2, and 4) of Eu3+, illustrating the asymmetric nature of the dopant sites in the glass.

Performance of small- and wide-angle x-ray scattering beamline at Indus-2 synchrotron

A Small- and Wide-Angle X-ray Scattering (SWAXS) beamline (BL-18) is installed and commissioned at a 1.5 T bending magnet port (5°) of Indus-2 synchrotron at RRCAT, Indore, India. The ∼40-m-long beamline has tunable x-ray energy in the range of 5–20 keV by using a double crystal monochromator. A 1.5-m-long toroidal mirror is used to focus the x-ray beam at the detector position. The beamline is equipped with a 6-m-long movable detector stage to access different wave-vector transfer ranges. At present, an online image plate area detector and a linear position-sensitive gas detector are installed for Small-Angle X-ray Scattering (SAXS) and Wide-Angle X-ray Scattering (WAXS) measurements, respectively. The beamline is operational in simultaneous SAXS/WAXS mode to probe the mesoscopic as well as molecular level structure over a wide range of wave-vector transfer. The specification of the beamline and its performance are reported here. A few recent experimental results, as obtained from BL-18, are also described in brief.

Structural evolution of the butylated hydroxytoluene/menthol hydrophobic eutectic solvent upon methanol and ethanol cosolvent addition

The changes upon methanol (MeOH) and ethanol (EtOH) addition in the structural arrangement of the hydrophobic eutectic solvent formed by butylated hydroxytoluene (BHT) and L-menthol (MEN) in 1:3 M ratio have been studied using molecular dynamics (MD) simulations integrated by small- and wide-angle X-ray scattering (SWAXS) measurements. Different mixtures containing the eutectic solvent and a variable amount of MeOH and EtOH have been investigated and the cosolvent introduction at any concentration has been found to break the hydrogen-bonds (H-bonds) among the MEN molecules, that are the most relevant interactions in the pristine eutectic, while the BHT component remains substantially non-interacting through all the explored composition range. This H-bond network is replaced by interactions between the MEN component and the cosolvent molecules, where the MEN species acts preferentially as H-bond donor towards the MeOH and EtOH molecules that behave mostly as H-bond acceptors. An increasing interplay between the excess cosolvent molecules is also observed upon increasing their concentration. SWAXS data show a contraction of the electron-dense regions corresponding to the hydroxyl groups upon cosolvent addition. This evidence is compatible with the intercalation of the MeOH and EtOH molecules in the MEN-MEN H-bond network to promote MEN-cosolvent and cosolvent-cosolvent interactions, in agreement with the MD results.

Effect of ion structure on the nanostructure and electrochemistry of surface active ionic liquids.

The ion structure of surface active ionic liquids (SAILs), i.e. ion charge group and alkyl chain structure, controls their bulk and interfacial nanostructure and the electrochemical properties near an electrode. The structures in the bulk and at the interface were investigated by small and wide-angle X-ray scattering (SAXS) and atomic force microscopy (AFM), respectively. An investigation was performed using cyclic voltammetry. All SAILs show pronounced sponge-like bulk nanostructure. For the first time, the bulk nanostructures of SAILs are found to change from anion bilayer structures to cation-anion interdigitated structures as the ion structures change from short alkyl chain cations and linear alkyl chain anions to long alkyl chain cations and branched alkyl chain anions. The bulk nanostructure packs more compactly at a higher temperature, likely due to the conformational change and enhanced interdigitations of alkyl chains. The thicknesses of SAIL interfacial layers align with the repeat distances of the bulk nanostructure, similar to conventional ILs with long cation alkyl chains. All SAILs have wide electrochemical windows >4V, which are not affected by the alkyl chain structure and cation charge groups.

Structural Approach to Understanding the Formation of Amorphous Metal Hydroxides.

This study investigates the formation of amorphous tetravalent metal hydroxides, M(OH)4, based on the structural analysis by small- and wide-angle X-ray scattering (SWAXS) and on the electrical potential charge near the surface of M(OH)4 particles. The amorphous zirconium hydroxide solid phases that aged in NaCl and CaCl2 solutions at 25 °C exhibited a hierarchical structure consisting of primary particles of a few nanometers in size and their aggregates more than 100 nm in size. The SWAXS profiles suggested that the size of the primary particles depends on the ionic strength and electrolytes in the sample solutions. The smaller size of the primary particles observed in solutions with higher ionic strength can be explained by the thinner electrical double layer. Additionally, we focused on the ζ potentials of M(OH)4 suspensions in NaCl, NaNO3, and CaCl2 solutions. With the aid of reference systems of metal oxides, MO2, it was found that the ζ potentials were well interpreted by a traditional surface ionization and complexation model, and the size distributions of large aggregates were explained by the classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory with the ζ potential values. The present study suggests the formation mechanism of amorphous metal hydroxides through a combination of structural analysis and investigation of electrical potentials.

Self-Assembled Structure of α-Isostearyl Glyceryl Ether Affects Skin Permeability-a Lamellar with 70-nm Spaces and L3 Phase Enhanced the Transdermal Delivery of a Hydrophilic Model Drug.

Self-assembled surfactant structures, such as liquid crystals, have the potential to enhance transdermal drug delivery. In the present study, the pseudo-ternary system of GET (composed of α-Isostearyl glyceryl ether (GEIS) and polysorbate 60)/1,3 butanediol (BG)/water) was shown to exhibit a complex phase diagram. Small- and wide-angle X-ray scattering (SWAXS) and freeze-fracture transmission electron microscopy (FF-TEM) revealed that GET6BG60 (6%GET/60%BG/34%Water) formed a lamellar phase with a repeated distance of approximately 72nm. Such a long-repeated distance of the lamellar phase was unique in the surfactant system. Moreover, the various structures, such as multilamellar vesicles and branched-like layers, were observed, which suggested that they might be deformable. On the other hand, only core-shell particles were observed in GET6BG20, the core of which was an L3 phase. GET6BG20 and GET6BG60 significantly enhanced the skin permeation of the hydrophilic model drug, antipyrine (ANP) (log Ko/w, - 1.51). However, their permeation profiles were distinct. Liquid chromatography-tandem mass spectrometry revealed that epidermal accumulation of GEIS was significantly higher with GET6BG60 than GET6BG20 after 1.5h of permeation, which might be attributed to differences in their deformable properties. Furthermore, GEIS was reported to affect intercellular lipids. Accumulated GEIS in the epidermis may have interacted with intercellular lipids and enhanced the transdermal delivery of ANP. The difference in the permeation profiles of ANP may be attributed to the penetration process of GEIS in the epidermis. This study suggests that GET6BG20 and GET6BG60 are unique carriers to enhance the permeation of hydrophilic drugs, such as ANP.

Structural Study of a Eutectic Solvent Reveals Hydrophobic Segregation and Lack of Hydrogen Bonding between the Components

An in-depth study of the hydrophobic eutectic solvent formed by butylated hydroxytoluene (BHT) and l-menthol (MEN) in a 1:3 molar ratio has been carried out using an integrated approach that combines differential scanning calorimetry (DSC), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, small- and wide-angle X-ray scattering (SWAXS), and molecular dynamics (MD) simulations. The obtained data have been step-by-step compared to those collected on the eutectic formed by 3,5-di-tert-butyltoluene (TBT) and MEN in the same molar ratio, where TBT is analogous to the BHT without the hydroxyl group. The DSC characterization showed comparable results between the two systems, evidencing that the hydroxyl group of the BHT has little or no impact on the thermal behavior of the BHT:MEN eutectic. Both the FTIR and MD results agree in finding that no hydrogen bond (H-bond) interactions are played by the BHT because of the high steric hindrance suffered by its hydroxyl group so that the only established H-bonds are those between MEN molecules. The incompatibility between the components in terms of H-bonds formation results in hydrophobic segregation promoting the MEN–MEN interactions, which are even more intense than in the pure compound. The three-dimensional arrangement between the components showed a remarkable degree of structural order among the alkyl functional groups, suggesting that the apolar–apolar attraction might be the driving force of the eutectic formation. This picture is translated into the establishment of an intermediate-range organization in solution, as evidenced by the SWAXS data. The overall impact of this study is that of pushing a little bit further the definition of these eutectics, indicated until now as extensively H-bonded systems.

Quantifying Concentration Fluctuations in Binary Glass-Forming Systems by Small- and Wide-Angle X-ray Scattering.

Functionality of amorphous multicomponent systems largely depends upon the miscibility among components, especially in systems such as amorphous drugs and electrolytes. An in-depth understanding of mixing behaviors of various constituents is necessitated. Here, we applied the small- and wide-angle X-ray scattering (SWAXS) technique to monitor the mixing behaviors in three typical glass-forming binary systems imposed by varied heat of mixing. It is found that the Porod invariant (Q) determined at the glass transition temperature is remarkably enhanced as the concentration fluctuation becomes intensified. Meanwhile, the deviation of Q from the ideal mixing law is markedly weaken at elevated temperatures. The results unambiguously suggest that the degree of concentration fluctuations in mixing systems can be accurately quantified by the structural property, allowing the link to mixing thermodynamics.

Intermolecular Dynamics and Structure in Aqueous Lidocaine Hydrochloride Solutions.

We investigated the intermolecular dynamics and static structure in the aqueous solutions of lidocaine hydrochloride (LDHCl) in the concentration range of [LDHCl] = 0-2.00 M using femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES), small- and wide-angle X-ray scattering (SWAXS), and dynamic light scattering (DLS). For the fs-RIKES experiments, the concentration dependence of the difference low-frequency spectra of the aqueous LDHCl solutions relative to the neat water, which was mainly due to the intermolecular vibrations, was characterized using an exponential function with a characteristic concentration of ∼1 M. For the SWAXS experiments, we observed a manifestation of an excess scattering component centered within a range of 8-10 nm-1 in the aqueous LDHCl solutions. The results of Fourier inversion and further deconvolution analyses unambiguously demonstrated that lidocaines assemble into a nanometer-sized micelle-like structure with the innermost core (∼0.3 nm) and outer shell (∼0.5 nm), respectively. The DLS experiments also found nanometer-sized aggregates and further indicated evidence of the clusters of the aggregates. The results of viscosities, densities, and surface tensions of the solutions and the quantum chemistry calculations supported the unique features of the microscopic intermolecular interaction and the micelle-like aggregation.

Phase Behavior of Drug-Lipid-Surfactant Ternary Systems toward Understanding the Annealing-Induced Change.

The present study systematically investigates the effect of annealing conditions and the Kolliphor P 407 content on the physicochemical and structural properties of Compritol (glyceryl behenate) and ternary systems prepared via melt cooling (Kolliphor P 407, Compritol, and a hydrophilic API) representing solid-lipid formulations. The physical properties of Compritol and the ternary systems with varying ratios of Compritol and Kolliphor P 407 were characterized using differential scanning calorimetry (DSC), small- and wide-angle X-ray scattering (SWAXS) and infrared (IR) spectroscopy, and hot-stage microscopy (HSM), before and after annealing. The change in the chemical profiles of different Compritol components as a function of annealing was evaluated using 1H NMR spectroscopy. While no change in the polymorphic form of API and Kolliphor P 407 occurred during annealing, a systematic conversion of the α- to β-form was observed in the case of Compritol. Furthermore, the polymorphic transformation of Compritol was found to be dependent on the Kolliphor P 407 content. As per the Flory-Huggins mixing theory, higher miscibility was observed in the case of monobehenin-Kolliphor P 407, monobehenin-dibehenin, and dibehenin-tribehenin binary mixtures. The miscibility of Kolliphor P 407 with monobehenin and 1,2-dibehenin was confirmed by 1H NMR analysis. The observed higher miscibility of Kolliphor P 407 with monobehenin and 1,2-dibehenin is proposed as the trigger for the physical separation from the 1,3-diglyceride and triglycerides during melt solidification of the formulations. The phase separation is postulated as the mechanism underlying the formation of a stable β-polymorphic form (a native form of 1,3-diglyceride) of Compritol upon annealing. This finding is expected to have an important implication for developing stable solid-lipid-surfactant-based drug formulations.

Biocompatibility of mesoporous SBA-16/hydroxyapatite nanocomposite and dentin demineralized particles on human dental pulp stem cells.

In the present work, a biomaterial (SBA-16/HA) based on the growth of hydroxyapatite (HA) particles within an organized silica structure SBA-16 (Santa Barbara Amorphous-16) was developed to evaluate its application to act as a porous microenvironment promoting attachment and viability of human dental pulp stem cells of healthy deciduous teeth (SHED). First, SHED were isolated and their phenotypes were evaluated by flow cytometry. The samples of SBA-16/HA were characterized by X-ray diffraction (XRD), small and wide angle X-ray scattering (SWAXS), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) equipped with energy dispersive spectra detector (EDS). Afterward, cells were cultured in the eluates of the above-mentioned biomaterial aged for 24 hr, 7. and 14 days. Bio-Oss® and dentin particles are involved for comparison and cells are cultured in the eluates of these two materials also. Thiazolyl Blue Tetrazolium bromide assay-MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide assay) was used for the determination of cell viability. The results obtained by all aforementioned characterization methods of SBA-16/HA, revealed a uniform spherical mesoporous structure, an intrinsic characteristic of this material. This material displayed excellent biocompatibility on SHEDs, and even proliferative potential, indicating that SBA-16/HA could potentially serve as a suitable substrate for bone regeneration. Contrary to SBA-16/HA, dentin particles showed low cytotoxicity at all time points, compared to control and Bio-Oss®groups. Our results substantiate the idea that SBA-16/HA has a beneficial effect on SHEDs, thus paving the way toward developing new material for bone replacement.

Fate of a Deep Eutectic Solvent upon Cosolvent Addition: Choline Chloride-Sesamol 1:3 Mixtures with Methanol.

The changes upon methanol (MeOH) addition in the structural arrangement of the highly eco-friendly deep eutectic solvent (DES) formed by choline chloride (ChCl) and sesamol in 1:3 molar ratio have been studied by means of attenuated total reflection Fourier transform infrared spectroscopy, small- and wide-angle X-ray scattering (SWAXS), and molecular dynamics simulations. The introduction of MeOH into the DES promotes the increase of the number of Cl–MeOH hydrogen bonds (HBs) through the replacement of sesamol and choline molecules from the chloride anion coordination sphere. This effect does not promote the sesamol–sesamol, choline–choline, and sesamol–choline interactions, which remain as negligible as in the pure DES. Differently, the displaced sesamol and choline molecules are solvated by MeOH, which also forms HBs with other MeOH molecules, so that the system arranges itself to keep the overall amount of HBs maximized. SWAXS measurements show that this mechanism is predominant up to MeOH/DES molar ratios of 20–24, while after this ratio value, the scattering profile is progressively diluted in the cosolvent background and decreases toward the signal of pure MeOH. The ability of MeOH to interplay with all of the DES components produces mixtures with neither segregation of the components at nanoscale lengths nor macroscopic phase separation even for high MeOH contents. These findings have important implications for application purposes since the understanding of the pseudophase aggregates formed by a DES with a dispersing cosolvent can help in addressing an efficient extraction procedure.

Enhanced formation of stereocomplex crystallites in Poly(l-lactic acid)/Poly(d-lactic acid) blends by silk fibroin nanodisc

Blending of poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) is known to form stereocomplex crystallites (SC). In this research, the impact of a biobased filler, silk fibroin nanodisc (SFN), on the crystallizability of the PLLA/PDLA (50/50) blend was examined by differential scanning calorimetry (DSC), polarizing optical microscope (POM), and time-resolved small- and wide-angle X-ray scattering (SWAXS) measurements. The crystallization temperature (Tc), measured by non-isothermal DSC cooling scan, was increased by the addition of 1% SFN in the PLLA/PDLA (50/50) blend. The inclusion of SFN enhanced the formation of SC, as indicated by increasing the melting enthalpy of SC. Isothermal crystallization study at 110 °C by DSC and WAXS suggested that the SFN enhanced the SC crystallization while it suppressed the homocrystal (HC) crystallization, as indicated by crystallization half-time (t0.5) values. It was found that SFN not only enhances the SC crystallizability but also increases the fraction of SC crystals in the PLLA/PDLA blend. The long period of HC and SC lamellar stack was reduced by the addition of SFN, as indicated by the SAXS results. The POM results suggested that SFN significantly enhanced the number of SC nuclei for the isothermal crystallization at 170 °C from the melt.

Rheology of α-Gel Formed by Amino Acid-Based Surfactant with Long-Chain Alcohol: Effects of Inorganic Salt Concentration.

Mixtures of surfactants, long-chain alcohols, and water sometimes yield lamellar gels with hexagonally packed alkyl chains. This assembly is called “α-gel” or “α-form hydrated crystal.” In this study, we characterized the rheological properties of α-gel prepared using disodium N-dodecanoylglutamate (C12Glu-2Na), 1-hexadecanol (C16OH), and water at different NaCl concentrations. The α-gel structure was assessed using small- and wide-angle X-ray scattering (SWAXS). The SWAXS measurements revealed that an increased NaCl concentration (0–200 mmol dm–3) resulted in a decreased d-spacing caused by the screening of electrostatic repulsion between lamellar bilayers. This led to an increased amount of excess water (i.e., the water present between the α-gel domains), and hence, the viscosity of the α-gel decreased in the range of the NaCl concentration. A further increase in the NaCl concentration (200–1000 mmol dm–3) resulted in decreased electrostatic repulsion between the α-gel domains and/or an increased number of α-gel domains (multilamellar vesicles). These effects increased the domain-to-domain interactions, leading to increased viscosity. Therefore, we concluded that the viscosity of the α-gel was controlled by the amount of excess water and the domain-to-domain interactions. Once the network structure collapsed under the strain, it was difficult to recover the original network structure. The low recoverability resulted from increased cohesion between the domains at high NaCl concentrations.