Salt Molecules Research Articles

Influence of Salt on the Self-Organization in Solutions of Star-Shaped Poly-2-alkyl-2-oxazoline and Poly-2-alkyl-2-oxazine on Heating.

The water–salt solutions of star-shaped six-arm poly-2-alkyl-2-oxazines and poly-2-alkyl-2-oxazolines were studied by light scattering and turbidimetry. The core was hexaaza[26]orthoparacyclophane and the arms were poly-2-ethyl-2-oxazine, poly-2-isopropyl-2-oxazine, poly-2-ethyl-2-oxazoline, and poly-2-isopropyl-2-oxazoline. NaCl and N-methylpyridinium p-toluenesulfonate were used as salts. Their concentration varied from 0–0.154 M. On heating, a phase transition was observed in all studied solutions. It was found that the effect of salt on the thermosensitivity of the investigated stars depends on the structure of the salt and polymer and on the salt content in the solution. The phase separation temperature decreased with an increase in the hydrophobicity of the polymers, which is caused by both a growth of the side radical size and an elongation of the monomer unit. For NaCl solutions, the phase separation temperature monotonically decreased with growth of salt concentration. In solutions with methylpyridinium p-toluenesulfonate, the dependence of the phase separation temperature on the salt concentration was non-monotonic with minimum at salt concentration corresponding to one salt molecule per one arm of a polymer star. Poly-2-alkyl-2-oxazine and poly-2-alkyl-2-oxazoline stars with a hexaaza[26]orthoparacyclophane core are more sensitive to the presence of salt in solution than the similar stars with a calix[n]arene branching center.

Changes in the Structure of the Benzylpenicillin Sodium Salt Molecule under the Pulsed Magnetic Field

The study aims at the Fourier spectra of an antibiotic exposed to a high-intensity pulsed magnetic field. The applied frequency was f = 40 kHz, with a number of pulses n = 1, at intensities of the pulsed magnetic field H = 0.09 × 106 А/m, Н = 0.50 × 106 А/m, Н = 0.82 × 106 А/m. It was assumed that under the conditions of the pulsed magnetic field there might be a change in the structure of the drug molecule. The research has revealed that an increase in the pulsed magnetic field power leads first to a decrease in the intensity of the band in the Fourier spectrum, and then to its increase. In addition, changes were recorded in the amide group of benzylpenicillin sodium salt molecules depending on the intensity of the pulsed magnetic field applied to the antibiotic.

Tuning lipid structure by bile salts: Hexosomes for topical administration of catechin

The delivery of bio-active molecules through the skin is challenging given the complex structure of its outer layer, the stratum corneum. Here we explore the possibility to encapsulate natural compounds into nanocarriers containing permeation enhancers that can affect the fluidity of the stratum corneum lipids. This approach is expected to facilitate dermal or transdermal release. For this purpose, the application of bile salts, which are natural surfactants involved in vivo in lipid digestion, was exploited.Bile salts were added to lipid liquid crystalline nanoparticles (NPs) made of monoolein for antioxidant topical delivery. Monoolein self-assembly behaviour in water was affected by the presence of bile salts molecules, giving a transition from a bicontinuous cubic to unilamellar vesicles dispersion. By adding oleic acid (OA), the change of curvature in the system led to a reverse hexagonal phase. The morphology, structure and size of the nanocarriers was investigated before the nanoparticles were loaded with catechin, a natural antioxidant occurring in plants and food. The encapsulation did not affect significantly the formulation phase behaviour. The formulation loaded with bile salts and catechin was thereafter tested in vitro on the skin from new-born pig. The results for two different lipid formulations without bile salts were compared under the same experimental conditions and with the same antioxidant. The formulation with bile salts showed the best performance, allowing a superior permeation of catechin in the different skin layers in comparison with formulations without bile salt.

Dynamics of third order direct three-body recombination of heavy ions.

The direct three-body recombination reactions Cs+ + X- + R → CsX + R (X = F, I and R = Ar, Xe) are studied within the quasiclassical trajectory method using diabatic semiempirical potential energy surfaces, the encounters of the ions being non-central. The collision energies range between 1 and 10 eV (values typical for low temperature plasma), while the so-called delay parameter, which characterizes the delay in the arrival of the neutral atom R in relation to the time instant when the distance between the ions attains its minimum, is equal to 0 or 20%. The calculation results include the recombination excitation functions, the opacity functions, and the vibrational and rotational energy distributions of the recombination products. All the four reactions considered exhibit similar overall statistical dynamics, but each process has its own features. On the whole, for both the recombining pairs Cs+ + F- and Cs+ + I-, xenon is more effective than argon as an acceptor of excess energy from the ion pair. The rotational energy distributions of the salt molecules CsF and CsI are almost equilibrium, whereas the vibrational energy distributions are strongly non-equilibrium.

Mechanical Flexibility of DNA: A Quintessential Tool for DNA Nanotechnology.

The mechanical properties of DNA have enabled it to be a structural and sensory element in many nanotechnology applications. While specific base-pairing interactions and secondary structure formation have been the most widely utilized mechanism in designing DNA nanodevices and biosensors, the intrinsic mechanical rigidity and flexibility are often overlooked. In this article, we will discuss the biochemical and biophysical origin of double-stranded DNA rigidity and how environmental and intrinsic factors such as salt, temperature, sequence, and small molecules influence it. We will then take a critical look at three areas of applications of DNA bending rigidity. First, we will discuss how DNA’s bending rigidity has been utilized to create molecular springs that regulate the activities of biomolecules and cellular processes. Second, we will discuss how the nanomechanical response induced by DNA rigidity has been used to create conformational changes as sensors for molecular force, pH, metal ions, small molecules, and protein interactions. Lastly, we will discuss how DNA’s rigidity enabled its application in creating DNA-based nanostructures from DNA origami to nanomachines.

Using solid-state nuclear magnetic resonance to rationalize best efficiency of 2,6-dihydroxybenzoic acid over other 2,X-dihydroxybenzoic acid isomers in solvent-free matrix-assisted laser desorption/ionization of poly(ethylene glycol).

Among isomers of dihydroxybenzoic acid (DHB), 2,5-DHB is often the most efficient matrix in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) for a great variety of compounds. Yet, when performing solvent-free MALDI, 2,6-DHB yields better results for poly(ethylene glycol [PEG]). This intriguing feature is explored here using solid-state nuclear magnetic resonance (NMR). Ternary mixtures were prepared by grinding 2,X-DHB (X = 3-6), poly(ethylene glycol) (Mn = 2000 g mol-1 ) and lithium fluoride (LiF) in a matrix/analyte/salt molar ratio of 50/1/10 for 16 min under a controlled atmosphere. After mixing, a few grains were applied to the MALDI target for MS analysis, whereas the major part of the ground sample was transferred into rotors to perform 13 C, 7 Li, and 19 F NMR experiments. Lithiated PEG chains are mainly formed with 2,6-DHB in solvent-free MALDI, but their abundance increases with 2,3-DHB and 2,4-DHB when water uptake is favored by a humid atmosphere. Solid-state NMR shows that grinding 2,6-DHB-based samples in atmospheric conditions leads to a solid phase in which the matrix, PEG, and salt molecules exhibit a high mobility compared with systems involving other 2,X-DHB isomers. This mobile environment would favor (as a solvent) LiF dissociation and best promote PEG cationization. Complementary data in 13 C, 7 Li, and 19 F NMR spectra are consistent with the formation of a solid phase of high mobility composed of 2,6-DHB, PEG, and the two salt components that ultimately favor the production of lithiated PEG chains.

Alternative Me-N-C Based Carbon Foams As Fe-Free and Non-PGM Electrocatalysts

There is a demand for reducing the environmental load of automobiles to solve the current environmental problems. Fuel cell electric vehicles (FCEVs) which use hydrogen as fuel emit no carbon dioxide, and have already been commercialized. platinum-based materials are widely used as oxygen reduction reaction (ORR) catalysts. However, their high cost and limited durability impedes large-scale implementation. Until now, non-platinum group metal (non-PGM) Fe and N doped carbon (Fe-N-C) catalysts have achieved promising ORR activity [1]. However, these Fe-N-C catalysts still suffer from poor durability, due to the formation of reactive peroxide radicals as a side reaction during the ORR. Meanwhile, the use of Co species avoids the production of such radicals, potentially preserving the electrocatalyst [2]. Therefore, in this study we investigate the dependence of ORR activity on a variety of different metal ions by synthesizing alternative Me-N-C carbon foam electrocatalysts (Me = Co, Ni, Sn).Pt-free electrocatalysts were synthesized from nitrogen-doped carbon foams (N-C) and various metal salt and small molecule precursors. Porous nitrogen-doped carbon foams with large surface area were made in-house. These were adsorbed with metal acetate and then heated in inert atmosphere, followed by acid washing to remove metallic phases. Finally, heat treatment under ammonia was performed. The effect of heat treatment temperature and metal loading on the microstructure and porosity was evaluated. The resulting catalysts were evaluated for catalytic activity using rotating-ring disk electrode voltammetry (RRDE) in acid.For Co-N-C electrocatalysts it was found that heat treatment of the nitrogen-doped carbon foam support has a significant effect on catalyst performance, largely due to changes in surface area and porosity. The metal loading also has a strong effect on the performance, with an optimum Co loading of 0.1 wt% resulting in an onset potential of 0.8 VRHE and a half-wave potential of around 0.65 VRHE. Different metal ions were also systematically investigated, and it was found that Sn is highly promising as an alternative to Fe in non-PGM electrocatalysts.

Supramolecular Polymers With AIE Property Fabricated From a Cyanostilbene Motif-Derived Ditopic Benzo-21-Crown-7 and a Ditopic Dialkylammonium Salt.

Fluorescent supramolecular polymers (FSP) have attracted considerable attention in recent years. Particularly, the incorporation of aggregation-induced emission (AIE) property to the FSP will bring this material into practical applications. Herein, we designed and synthesized a cyanostilbene motif derived ditopic benzo-21-crown-7 (B21C7) as a host molecule (H). The cyanostilbene motif endows H with AIE property while the B21C7 motif renders it with the capability to complex with electron deficient guest molecules. Upon the addition of a ditopic dialkylammonium salt molecule (G), a novel FSP with blue luminescent property can be constructed. This B21C7-based host-guest FSP with blue fluorescence may have potential application in supramolecular luminescent materials.

Role of outer layer configuration on saline concentration sensitivity of optical fiber probe coated with ZnO/Ag nano-heterostructure

Accurate monitoring of concentration changes in saline solution is prerequisite to control and minimize the negative effect of salt in water resources. A highly sensitive refractive index (RI) sensor is fabricated via coating a novel zinc oxide/silver (ZnO/Ag) bi-layer having different ZnO nanostructure shapes as an outer layer on partially unclad silica fiber. When the ZnO layer contact to different saline concentrations, its band-gap is altered and modifies the RI of the ZnO layer. The coupling of the evanescent light with surface plasmon resonance (SPR) wave and absorption of evanescent light by the external medium are responsible for observing wavelength shift and intensity changes in the detected spectrum. For vertically oriented ZnO nanorods sample when IR light is used as a light source, by increasing the saline concentration from 0% to 20%, the wavelength is shifted from 1564.4 nm to 1573.3 nm and the intensity is dropped to 77% of its maximum value. The superior sensitivity obtained for vertically oriented ZnO sample is attributed to the larger surface area, higher average dispersion relation, better crystallinity, larger surface roughness and greater adhesion (interaction) with salt molecules compare to the other samples. The experimentally demonstrated highest intensity and wavelength sensitivity are 36 dB/RIU and 255 nm/RIU respectively.

Crystal structures of salts of bedaquiline.

Bedaquiline [systematic name: 1-(6-bromo-2-methoxyquinolin-3-yl)-4-(dimethylamino)-2-(naphthalen-1-yl)-1-phenylbutan-2-ol, C32H31BrN2O2] is one of two important new drugs for the treatment of drug-resistant tuberculosis (TB). It is marketed in the US as its fumarate salt {systematic name: [4-(6-bromo-2-methoxyquinolin-3-yl)-3-hydroxy-3-(naphthalen-1-yl)-4-phenylbutyl]dimethylazanium 3-carboxyprop-2-enoate, C32H32BrN2O2+·C4H3O4-}, and about a dozen other salts of bedaquiline have been described in patent literature, but none have so far been structurally described. In a first communication, we present the crystal structure of bedaquilinium fumarate and of two new benzoate salts, as well as that of a degradation product of the reaction of bedaquilinium fumarate with sodium ethoxide, 3-benzyl-6-bromo-2-methoxyquinoline, C17H14BrNO. The fumarate and benzoate salts both feature cations monoprotonated at the dimethylamino group. The much less basic quinoline N atom remains unprotonated. Both salts feature a 1:1 cation-to-anion ratio, with the fumarate being present as monoanionic hydrofumarate. The conformations of the cations are compared to that of free base bedaquiline and with each other. The flexible backbone of the bedaquiline structure leads to a landscape of conformations with little commonalities between the bedaquiline entities in the various structures. The conformations are distinctively different for the two independent molecules of the free base, the two independent molecules of the hydrofumarate salt, and the one unique cation of the benzoate salt. Packing of the salts is dominated by hydrogen bonding. Hydrogen-bonding motifs, as well as the larger hydrogen-bonded entities within the salts, are quite similar for the salts, despite the vastly differing conformations of the cations, and both the hydrofumarate and the benzoate structure feature chains of hydrogen-bonded anions that are surrounded by and hydrogen bonded to the larger bedaquilinium cations, leading to infinite broad ribbons of anions, cations, and (for the benzoate salt) water molecules. The benzoate salt was isolated in two forms: as a 1.17-hydrate (C32H32BrN2O2+·C7H5O2-·1.166H2O), obtained from acetone or propanol solution, with one fully occupied water molecule tightly integrated into the hydrogen-bonding network of anions and cations, and one partially occupied water molecule [refined occupancy 16.6 (7)%], only loosely hydrogen bonded to the quinoline N atom. The second form is an acetonitrile solvate (C32H32BrN2O2+·C7H5O2-·0.742CH3CN·H2O), in which the partially occupied water molecule is replaced by a 74.2 (7)%-occupied acetonitrile molecule. The partial occupancy induces disorder for the benzoate phenyl ring. The acetonitrile solvate is unstable in atmosphere and converts into a form not distinguishable by powder XRD from the 1.17-hydrate.

Simple Analysis of Primary and Secondary Bile Salt Hydrolysis in Mouse and Human Gut Microbiome Samples by Using Fluorogenic Substrates

Animals produce bile to act as an antibacterial agent and to maximize the absorption of lipophilic nutrients in the gut. The physical properties of bile are largely dictated by amphipathic bile salt molecules, which also participate in signaling pathways by modulating physiological processes upon binding host receptors. Upon excretion of bile salts from the gall bladder into the intestine, the gut microbiota can create metabolites with modified signaling capabilities. The category and magnitude of bile salt metabolism can have positive or negative effects on the host. A key modification is bile salt hydrolysis, which is a prerequisite for all additional microbial transformations. We have synthesized five different fluorogenic bile salts for simple and continuous reporting of hydrolysis in both murine and human fecal samples. Our data demonstrate that most gut microbiomes have the highest capacity for hydrolysis of host-produced primary bile salts, but some microbially modified secondary bile salts also display significant turnover.

Rigorous analysis of non-ideal solubility of sodium and copper chlorides in water vapor using Pitzer-Pabalan model

Gaseous mixtures of water vapor and neutral molecules of salt (e.g., NaCl, CuCl etc.) can be highly non-ideal due to a strong attractive interaction between salt and water molecules. In particular, this can result in high solubility of salts in water vapor and a strong dependence of solubility on vapor pressure. The analysis of salt solubility in water vapor can be done using the Pitzer-Pabalan model, which is based on the thermodynamic theory of imperfect gases. The original Pitzer-Pabalan work demonstrated that one can reproduce experimental data for NaCl solubility in vapor. No analysis was performed on the reliability of their original fits, which we believe has contributed to the lack of applications of the Pitzer-Pabalan model despite the apparent success of the original paper. In this work, we report our recent progress in developing a rigorous fitting procedure to parameterize the Pitzer-Pabalan model using experimental data. Specifically, we performed fitting of the experimental results obtained elsewhere for NaCl and CuCl. We investigate the degree of underfitting/overfitting and the sensitivity of the fitting quality to variations in the resulting fitting parameters. The results, as represented by the thermodynamic parameters describing the energetics of formation of salt-bearing water clusters, were successfully benchmarked against Gaussian 16 ab initio quantum chemistry calculations. The resulting rigorous fitting procedure presented here can now be applied to other systems.

Reliable Langmuir Blodgett colloidal masks for large area nanostructure realization

The fabrication of highly ordered nanostructures over large areas is key for many technologies and colloidal lithography using the Langmuir Blodgett technique appears a simple and straightforward way of reaching that goal. While this technique has been widely reported in the literature, its straightforward implementation to obtain well-ordered nanostructures over very large areas is far from obvious, since many key technical subtleties are rarely documented. Here, we describe an easily and highly reproducible recipe and detail aspects such as beads preparation, composition of the subphase, beads transfer method, influence of the spreading agent and the barrier compression rate, as well as monolayer transfer to the substrate. A drastic improvement in the polystyrene self-assembly at the air-water interface is observed after removing the common salt and surfactant molecules from commercial polystyrene beads suspensions. Similarly, an electrolyte free water subphase enhances the hexagonal arrangement of the beads and the long-range order. The beads sinking into the bulk of the water is reduced by dispensing the beads using a glass slide and the polystyrene suspension prepared using water and ethanol at 1:1 mitigates repulsive and attractive forces, leading to excellent hexagonal close packed arrangement. By following the recipe shown here, the reader should easily fabricate lattice-like colloidal masks for producing nanostructures over larger areas.

Au–Pt–Pd spherically self-assembled nano-sieves as SERS sensors

Abstract A series of unique granular and petaloid Au-capped Pt–Pd spherically-assembled nano-sieves (Au-PP SANSs) – with diameters smaller than 100 nm, combining quasi-regularly integrated surface-enhanced Raman scattering (SERS) active nanocrystals and a functional amphiphilic organic frame – have been successfully synthesized through a facile chemical route with a temperature-sensitive triblock copolymer soft template. Further, it has been demonstrated that they are potential candidates for developing highly-selective molecule-sieve assisted SERS sensors. The combination of the superposed inorganic and organic dual-core shell structures in Au-PP SANSs acts as a molecular sieve, which plays a crucial role in the promising chemical selectivity, which helps distinguish polar malachite green oxalate salt and non-polar thiabendazole molecules.

Hydrogen bond interactions of hydrated aluminum nitrate with PVDF, PVDF‐TrFE, and PVDF‐HFP: A density functional theory‐based illustration

AbstractHydrogen bond (HB) interaction is the main driving factor for the nucleation of electroactive β phase within the nonpolar pristine polyvinylidene fluoride (PVDF) and its copolymers when the hydrated nitrate salts act as additives. The current work elaborates a density functional theory‐based analysis on the HB interactions within aluminum nitrate nonahydrate‐added polyvinylidene fluoride [PVDF/Al(NO3)3∙9H2O], polyvinylidene fluoride‐trifluoro ethylene [PVDF‐TrFE/Al(NO3)3∙9H2O], and polyvinylidene fluoride‐hexafluoro propylene [PVDF‐HFP/Al(NO3)3∙9H2O] composite systems. Polar properties of α (TGTG′) and β (TTTT) phases of the homopolymer and copolymer chains have been compared. Coordination chemistry and formation energies of two stable isomers of Al(NO3)3∙9H2O have been described. Interactions within the polymer/salt complexes have been simulated considering both the salt isomers added to α‐ and β‐tetramer chains of PVDF, PVDF‐TrFE, and PVDF‐HFP. An integral equation formalism polarizable continuum model has been used to replicate the effects of n,n‐dimethyl formamide solvent. HB interaction phenomenon has been described on the basis of electron density difference, interaction energy calculations, symmetry‐adapted perturbation theory, natural bond orbital, Bader's quantum theory of atoms in molecules, delocalization indices, and reduced density gradient analyses. Simulated infra red (IR) and Raman spectra identified the simultaneous presence of CH⋯O (mostly improper) and OH⋯F (mostly proper) HBs between the salt molecule and polymer chains. Correlations among different HB descriptors have been demonstrated to compare the proper and improper nature of the bonds. This research explored some ambiguities in the conventional HB properties, which may be attributed to very low hyperconjugation energies associated with the bonds.

Dynamical and turbo TDDFT study of polyaniline emeraldine for CO, NH3, CO2 gas sensing

The adsorption of gas molecules (CO, NH$_3$, CO$_2$ ) on Polyaniline Emeraldine salt has been performed to study gas sensing. Density functional theory (DFT) and time dependent density functional theory (TD-DFT) calculations have been carried out to compute the response mechanism of polyaniline emeraldine salt (PANI ES) oligoanalinines (with two to six rings) to gas molecules. The optimized geometry and electronic structure corresponding to molecule and complexes are computed with the pseudo-potential and full-potential methods. The absorption spectra corresponding to polyaniline emeraldine salt molecule and its complexes are calculated using TD-DFT. We found it out that the electronic and optical features corresponding to complexes show more sensitive to the NH$_3$ adsorption. The optical absorption spectrum analysis was used for all ( nPANI ES-X ) and isolated nPANI ES. Then, the related spectrum indicates that the $\lambda_{max}$ is shifted red or blue, is affected by the kind of complex.

Molecular interactions analysis of some aluminium salts in binary aqueous solutions of tetrahydrofuran (THF): Acoustic and Conductometric approach

In the present investigation conductance and speed of sound of aluminium sulphate, aluminium nitrate, and aluminium chloride were experimentally determined in aqueous medium as well in binary aqueous mixtures of THF. Various conductance and acoustic parameters viz; molar conductance, limiting molar conductance, partial molar adiabatic compressibility, coefficient of adiabatic compressibility were also determined using Kohlrausch's Law, Debye-Huckel theory and Masson’s equation at working temperatures and different compositions of THF. Analysis reveals that limiting molar conductivity decreases with increase in composition of THF in water indicating the decrease in the ion-solvent interactions with increase in composition THF in water. Further it was found that with increase in temperature the values increase for all the three salts which support the increase in ion-solvent interactions with increase in temperature. The values of partial molar isentropic compression were found negative and these values further increase with increase in composition of THF indicating that on increase in composition, attractive interactions develop between THF and water which induces dehydration of aluminium salts which make the water molecules of aluminium salts more compressible than that of lower THF concentration resulting in decrease of ion solvent interactions with increase in THF composition in water. On the other hand with increase in temperature, the values of further increase leading to increase in ion-solvent interactions of aluminium salts in water and 5% THF+ water. Walden product and its temperature coefficient i.e. have also been calculated which confirms that aluminium salts act as structure breaker in different compositions of THF in water.

Single-layered GO/LDH hybrid nanoporous membranes with improved stability for salt and organic molecules rejection

Graphene oxide (GO) has been intensively adopted as the building block of separation membranes due to its excellent mechanical strength and atomic scale interlayer spacing. However, the practical application of GO nanosheet-based membranes are limited by the swelling and disintegration of GO membranes in water owing to hydration and electrostatic repulsion. In this work, we firstly fabricated a type of layered double hydroxide (LDH) nanosheets, Co(OH)2 nanosheets, by in-situ growth on the surface of GO nanosheets, followed by coating such GO/Co(OH)2 hybrid nanosheets on a microporous substrate through vacuum suction to form a single-layered GO/Co(OH)2 hybrid thin membrane. The electrostatic and coordination interactions between GO and Co(OH)2 nanosheets are found to stabilize the GO/Co(OH)2 hybrid membrane in water, and the hybrid membrane shows good resistance to shear force in a pressurized crossflow nanofiltration system with crossflow speed as high as 0.5 m s−1. With permeation flux up to 17.0 L m−2 h−1, >91% rejection to inorganic salts like Na2SO4 and >98% rejection to various organic dyes (transmembrane pressure: 6 bar, crossflow speed: 0.27 m s−1), the hybrid membrane also survives the challenges of different pH environments, elevated transmembrane pressure and a 60 h continuous crossflow test. Such significantly improved stability from pure GO membranes is expected to enable the 2D nanomaterial based membranes for practical filtration applications in the water industry.

Influence of clay modification process in polypyrrole-layered silicate nanocomposite

This work focuses mainly on the preparation and characterization of polypyrrole/organically modified clay nanocomposites. Organoclay/polypyrrole nanocomposites were prepared by oxidative polymerization of pyrrole in aqueous medium using ferric chloride as the oxidant. Initially, cetyltrimethyl-ammonium bromide and tetrabutyl-ammonium hydrogen sulphate were used as organophilic to modify clay and form an organic clay. After that, polypyrrole/organically modified clay nanocomposites were synthesized by in situ polymerization process in which pyrrole was polymerized in the presence of different proportions of organic clay. The effects of the nature of the organic clays and the preparation method were studied in order to evaluate their structural, morphological and thermal properties. X-ray diffraction (SAXS), Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, transmission electron microscopy, were used to define the characteristics of the materials obtained. The obtained results confirm the intercalation of molecules of salt in the clay layers, and good interaction with the polymer. Thermogravimetric analysis showed better thermal stability of nanocomposites compared to pure polypyrrole. The conductivity behaviour of nanocomposites was also examined.

Interaction of PEO with LiI/NaI: a density functional approach

The first-principles study of alkali halides dispersed in polyethylene chains is performed, the dispersion of salts modifies the bond lengths of atoms, bending of polymer chains is occurred, and Li/Na cations are found to be attracted towards oxygen anions; it causes to the reduction in crystallinity. Charge density analysis exhibits partially ionic and covalent bonds between C and O atoms of all PEO systems, and ionic bonds between Li and O and between Na and O atoms. There is sp hybridization in all polymer systems; the forbidden energy gap reduces gradually by increasing dispersed salt molecules and is smaller in PEO10–4NaI. The formation of the concentration of Na cations is higher than Li cations in polymer salts. The stability of PEO10–4LiI is larger and that of PEO5–LiI is smaller, and the bond breaking energy is higher in PEO10–4NaI and lower in PEO10–2NaI.