Nanocomposites Based on Poly(Amide-Imide) Matrix with Na–Mg Triple Chain Hydrosilicate

Crystallography Reports - A new polymer-inorganic nanocomposite composed of fibrous Na–Mg triple chain hydrosilicate with a poly(amide-imide) matrix was developed. Its structure, morphology,...     

Morphology and mechanical properties of polymer-inorganic nanocomposite containing triple chain fibrous Na-Mg hydrosilicate

Russian Journal of General Chemistry - A polymer-inorganic nanocomposite of fibrous Na-Mg triple chain hydrosilicate and polyamidoimide based on 4-chloroformyl-(N-p-chloroformylphenyl)phthalimide...     

Polyelectrolyte complexes. V. Solid‐state properties of some polycation/azo dye complexes controlled by the dye structure

The solid‐state properties of some polycation/azo dye complexes according to the dye structure were studied in this work. One polycation contained about 95 mol % N,N‐dimethyl‐2‐hydroxypropyleneammonium chloride units in the backbone (PCA₅), and eight azo dyes, different in either the number of sulfonic groups or their distribution, were used as opposite components. The selected azo dyes were as Crystal Scarlet, Congo Red, Crocein Scarlet MOO, Ponceau SS, Amaranth, Ponceau S, Direct Blue 1, and Direct Red 80. Information on the compensation degree of the oppositely charges was obtained by the elemental analysis of the solid‐state polycation/dye complexes (the experimental contents of chlorine, nitrogen, and sulfur were compared with the calculated values). Differential scanning calorimetry was employed to probe the strength of the intermolecular interactions in the PCA₅/dye complexes. Wide‐angle X‐ray diffraction was used to assess the supramolecular order of the solid‐state complexes. The physical properties of the PCA₅/azo dye complexes (the complex stoichiometry, glass‐transition temperature, decomposition temperature, and degree of supramolecular order) were influenced mainly by the dye structure but also by the polycation concentration and the presence of NaCl. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 264–272, 2003     

Relationship between the component synthesis order of zinc ferrite–titania nanocomposites and their performances as visible light-driven photocatalysts for relevant organic pollutant degradation

The main objective of this work was to investigate the influence of the order of component synthesis of zinc ferrite–titania nanocomposites on their structural, morphologic, textural, light absorption properties, and performances as photocatalysts. In this respect, nanocomposite materials with 10ZnFe₂O₄90TiO₂ (wt %) composition were prepared via a two-step synthesis procedure by alternating the order of the component addition during the preparation protocol and characterized by X-ray diffraction, transmission electron microscopy, energy dispersive X-ray, small-angle X-ray scattering, nitrogen sorption, and UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of nanocomposites was evaluated on Rhodamine 6G degradation under visible light illumination. The photocatalytic performances of nanocomposites were clearly superior to the classical TiO₂. Nevertheless, preparing titania in the presence of a presynthesized zinc ferrite led to superior characteristics in terms of band gap value, specific surface area, and grain sizes crucial for the enhancement of the photocatalytic performances.     

Structure, morphology, and thermal properties of nanocomposites based on polyamido imide and hydrosilicate nanotubes

New nanocomposites based on heat-resistant poly[(diphenyl oxide)amido-N-phenylphthalimide] with Mg₃Si₂O₅(OH)₄ hydrosilicate nanoparticles of tubular structure were prepared. The structure, morphology, and thermal properties of the nanocomposites were studied in relation to the content of hydrosilicate nanotubes.     

The influence of methoxy side groups and halogen nature on the mesomorphic and optical properties of symmetrical azomethines

The preparation, characterisation, thermotropic and optical properties of low-molecular azomethines with or without methoxy side group are described in this paper. The azomethine compounds were synthesised by condensation reaction of o-dianisidine/benzidine with para-halogen substituted benzaldehyde. Their properties were analysed by differential scanning calorimetry, thermogravimetry analysis, polarised optical microscopy, X-ray diffraction and optical spectroscopy. The azomethines present liquid crystalline behaviour with large mesophase range and high thermal stability. The compounds without lateral methoxy groups showed smectic A phase, while those with methoxy groups exhibited only nematic phase. The effect of methoxy group and different terminal substituents on the mesomorphic behaviour, molecular and optical properties was estimated in terms of parameters such as molecular polarisability, dipole moment, interdigitation parameter and axial ratio.     

Asymmetric azomethine amines with azobenzene moieties – liquid crystalline and optical properties

ABSTRACT

Three asymmetric azomethine-azobenzene intermediates (M1-M3), having internal reactive amine functional group, and both n-butoxy and p-chloro, p-methyl, o-methyl terminal moieties, have been synthesised by reacting asymmetric substituted azobenzene diamines with 4-butoxybenzaldehyde. Their proposed chemical structures were confirmed by FTIR and 2D-NMR spectroscopy. The mesomorphic behaviour was investigated by polarised optical microscopy (POM), differential scanning calorimetry (DSC) and room temperature powder X-ray diffraction techniques. Characteristic textures of smectic A and nematic phases have been observed for samples M1 and M2, while only unsolved texture was revealed for sample M3 at room temperature, showing sharp reflections in the medium-wide angle region. From X-ray diffraction measurements, a layered ordered structure of all compounds was established by analyzing successive scattering vectors ratios (q_i/q₁). The dependence of thermal behaviour on molecular parameters like: interdigitation parameter γ, dipole moment, molecular polarisability, halogen radius, was commented. The UV-Vis spectral investigations of the intermediates, performed in six solvents, revealed that the absorption bands were influenced by the substituent nature.     

Studies on the Chemistry of [Cd(NH3)4](MnO4)2. A Low Temperature Synthesis Route of the CdMn2O4+x Type NOx and CH3SH Sensor Precursors

Abstract. [Tetraamminecadmium(II)] bis(permanganate) ( 1 ) was prepared and its crystal structure was elucidated with XRD‐Rietveld refinement and vibrational spectroscopic methods. Compound 1 has a cubic lattice consisting of a 3D hydrogen‐bonded network built as four by four distorted tetrahedral blocks of [Cd(NH₃)₄]²⁺ cations and MnO₄^– anions, respectively. The other four permanganate ions are located in a crystallographically different environment, placed in the cavities formed by the attachment of the building blocks. A low‐temperature (≈100 °C) solid phase quasi‐intramolecular redox reaction producing ammonium nitrate and amorphous CdMn₂O₄ could be established. Neither solid phase nor aqueous solution phase thermal deammoniation of compound 1 can be used to prepare Cd(MnO₄)₂ and [Cd(NH₃)₂(MnO₄)₂]. During deammoniation of compound 1 in aqueous solution a precipitate consisting of Cd(OH)₂ forms. Additionally, solid MnO₂ and ammonium permanganate (NH₄MnO₄) forms. The solid phase deammoniation reaction (toluene used as heat convecting medium) with subsequent aqueous leaching of the ammonium nitrate formed has proved to be an easy and convenient technique for the synthesis of amorphous CdMn₂O_4+x type NO_x and MeSH sensor precursors. The 1 ‐ D perdeuterated complex was also synthesized to distinguish the N–H(D) and O–H(D) fragment signals in the TG‐MS spectra and to elucidate the vibrational characteristics of the overlapping Mn–O and Cd–N frequencies.     

FTIR investigations of phase transitions in an asymmetric azomethine liquid crystal

The liquid crystalline (LC) behavior of a literature-reported asymmetric azomethine compound (4-[4-(n-butyloxy)-benzylideneimino]-chlorobenzene, Cl.O4) was investigated by using optical polarized light microscopy, differential scanning calorimetry and medium-wide angle X-ray diffraction. FTIR in attenuated total internal reflection configuration was employed to study the microstructural changes occurring during phase transitions of the azomethine. Spectral modifications, associated with molecular conformation rearrangements, allowing the change of the molecular shape from a LC organization to another, have been found. The spectral analysis gave significant evidences for the different phase transitions, thus proving the efficiency of such method for investigating LC materials.     

Studies on the Chemistry of Tetraamminezinc(II) Dipermanganate ([Zn(NH3)4](MnO4)2): Low‐Temperature Synthesis of the Manganese Zinc Oxide (ZnMn2O4) Catalyst Precursor

Tetraamminezinc(II) dipermanganate ([Zn(NH₃)₄](MnO₄)₂; 1 ) was prepared, and its structure was elucidated with XRD‐Rietveld‐refinement and vibrational‐spectroscopy methods. Compound 1 has a cubic lattice consisting of a 3D H‐bound network built from blocks formed by four MnO anions and four [Zn(NH₃)₄]²⁺ cations. The other four MnO anions are located in a crystallographically different environment, namely in the cavities formed by the attachment of the building blocks. A low‐temperature quasi‐intramolecular redox reaction producing NH₄NO₃ and amorphous ZnMn₂O₄ could be established occurring even at 100°. Due to H‐bonds between the [Zn(NH₃)₄]²⁺ cation and the MnO anion, a redox reaction took place between the NH₃ and the anion; thus, thermal deammoniation of compound 1 cannot be used to prepare [Zn(NH₃)₂](MnO₄)₂ (contrary to the behavior of the analogous perrhenate (ReO ) complex). In solution‐phase deammoniation, a temperature‐dependent hydrolysis process leading to the formation of Zn(OH)₂ and NH₄MnO₄ was observed. Refluxing 1 in toluene offering the heat convecting medium, followed by the removal of NH₄NO₃ by washing with H₂O, proved to be an easy and convenient technique for the synthesis of the amorphous ZnMn₂O₄.