Synthesis and characterization of new thermally stable copoly(ester–amide)s from diester–dicarboxylic acids

Three new aromatic diester–dicarboxylic acids containing furan rings, namely, benzofuro[2,3-b]benzofuran-2,9-dicarboxyl-bis-phenyl ester-4,4^′-dicarboxylic acid, benzofuro[2,3-b]benzofuran-2,9-dicarboxyl-bis-phenyl ester-3,3^′-dicarboxylic acid and benzofuro[2,3-b]benzofuran-2,9-dicarboxyl-bis-naphthyl ester-2,2^′-dicarboxylic acid were synthesized by the reaction of benzofuro[2,3-b]benzofuran-2,9-dicarbonyl chloride with 4-hydroxybenzoic acid, 3-hydroxybenzoic acid and 3-hydroxy-naphthalene-2-carboxylic acid, respectively. Diester–dicarboxylic acids were characterized by FT-IR and NMR spectroscopy and elemental analyses. Then, these monomers were converted to aromatic copoly(ester–amide)s by their reaction with various aromatic diamines via the direct polycondensation. These polymers were characterized by viscosity measurements, solubility tests, FT-IR, Ultraviolet and ¹H-NMR spectroscopy and thermogravimetry. The polymers with inherent viscosities in the range of 0.16–0.37 dl/g in dimethyl sulfoxide at 30 °C were obtained in high yield. Most of them dissolved readily at room temperature in polar solvents. The synthesized copoly(ester–amide)s possessed glass-transition temperatures from 210–255 °C. The copoly(ester–amide)s exhibited excellent thermal stabilities and had 10% weight loss at temperature above 295 °C under nitrogen atmosphere.     

Aromatic polyether, -ketone, -sulfones as laminating resins. XII. Derivatives of 2,2′-diphenylethynyldiphenyl which cure by an intramolecular cyclization

Polymers made from 2,2′-diiododiphenyl-4,4′-dicarbonyl dichloride, diphenyl ether, and isophthaloyl chloride have been made and converted to the 2,2′-diphenylethynyl derivatives. Introduction of units of isophthaloyl chloride reduced the melting point of these polymers to about 200°C, and they could then be cured by heating. A good glass laminate was prepared and cured from one of the polymers.     

Enantioselective Diethylzinc Addition to Aromatic Aldehydes Catalyzed by Novel Ti(IV) Complex of Three-Dentate Chiral Sulfonamide Ligands

The synthesis of several novel three-dentate sulfonamide alcohol ligands is described, starting from camphorsulfonyl chloride. The influence of temperature and ligand structure on the asymmetric addition of dietylzinc to aromatic aldehydes has been studied. Enantioselectivities up to 76% have been obtained.     

Template‐Free Synthesis of Highly b‐Oriented MFI‐Type Zeolite Thin Films by Seeded Secondary Growth

Highly b‐oriented, closely packed, MFI zeolite films are prepared on seeded stainless‐steel plates using organic template‐free, secondary growth solutions, containing aluminum sulfate as a crystallization agent. The number of a‐oriented twin crystals is significantly reduced, and even eliminated, simply by restricting the pH value of the secondary growth solution to the narrow range of 11.1–11.3. Values of pH can be adjusted through the controlled addition of (NH₄)₂SO₄ or H₂SO₄ to secondary growth solutions of the composition (1 SiO₂:0.57 NaOH:137.5 H₂O:0.0050 (Al₂(SO₄)₃?18 H₂O)) or by simply decreasing the molar composition of NaOH with no extra additives.     

Experimental study of the effect of disk obstacle rotating with Different angular ratios on heat transfer and pressure drop in a pipe with turbulent flow

Journal of Thermal Analysis and Calorimetry - This article presents the effects of a circular disk obstacle with different angle ratios on heat transfer and pressure drop under a turbulent flow...     

Aromatic polyether, -ketone, -sulfones as laminating resins. XI. Polymers derived from 2,2′-diiododiphenyl-4,4′-dicarboxylic acid

Aromatic polyether-keto-sulfone polymers and related model compounds have been synthesized from 2,2′-diiododiphenyl-4,4′-dicarboxylic acid and a variety of intermediates. It was hoped to convert them to 2,2′-diphenylethynyl derivatives which could be cured by rearrangement to give dibenzanthracene units in the chain. Low solubilities and high melting points of the products prevented their use in the desired manner.     

Antiferromagnetic exchange coupling in amorphous Fe–Sc alloys

Results of ⁵⁷Fe Mössbauer, AC and DC susceptibility, grazing incidence X-ray diffraction, resistivity and Rutherford-backscattering measurements on the amorphous alloys ${\text{Fe}}_{100 - x} {\text{Sc}}_x (8 \leqslant x \leqslant 70)$ give for the first time convincing evidence for the antiferromagnetic exchange coupling between Fe-moments. The antiferromagnetic coupling between Fe-moments is for $(8 \leqslant x \leqslant 70)$ limited to certain regions (magnetic clusters) of the sample. The nature of the coupling is of the Heisenberg type. For $8 \leqslant x < 20$ , the magnetic coupling between Fe-moments is across nonmagnetic Sc-atoms. The conduction electrons mediate an indirect magnetic interaction between the Fe-moments. The magnetic exchange coupling between Fe-moments across Sc-atoms is negative. The antiferromagnetic coupling between Fe-moments can be explained by the Ruderman-Kittel-Kasuya-Yosida, RKKY, interaction by taking into account the damped oscillatory behavior of the RKKY interactions.     

Sol–gel-based silver nanoparticles-doped silica – Polydiphenylamine nanocomposite for micro-solid-phase extraction

A nanocomposite of silica-polydiphenylamine doped with silver nanoparticles (Ag–SiO₂-PDPA) was successfully synthesized by the sol–gel process. For its preparation, PDPA was mixed with butanethiol capped Ag nanoparticles (NPs) and added to the silica sol solution. The Ag NPs were stabilized as a result of their adsorption on the SiO₂ spheres. The surface characteristic of nanocomposite was investigated using scanning electron microscopy (SEM). In this work the Ag–SiO₂-PDPA nanocomposite was employed as an efficient sorbent for micro-solid-phase extraction (μ-SPE) of some selected pesticides. An amount of 15 mg of the prepared sorbent was used to extract and determine the representatives from organophosphorous, organochlorine and aryloxyphenoxy propionic acids from aqueous samples. After the implementation of extraction process, the analytes were desorbed by methanol and determined using gas chromatography–mass spectrometry (GC–MS). Important parameters influencing the extraction and desorption processes such as pH of sample solution, salting out effect, type and volume of the desorption solvent, the sample loading and eluting flow rates along with the sample volume were experimentally optimized. Limits of detection (LODs) and the limits of quantification (LOQs) were in the range of 0.02–0.05 μg L⁻¹ and 0.1–0.2 μg L⁻¹, respectively, using time scheduled selected ion monitoring (SIM) mode. The relative standard deviation percent (RSD %) with four replicates was in the range of 6–10%. The applicability of the developed method was examined by analyzing different environmental water samples and the relative recovery (RR %) values for the spiked water samples were found to be in the range of 86–103%.