Nataliya M. Belomoina

Synthesis and study of aromatic polyamides containing silicon and phenylquinoxaline rings in the main chain

Abstract New poly(phenylquinoxaline-amide)s with silicon in the main chain have been prepared by polycondensation reaction of a diacid chloride, namely bis( p -chlorocarbonyl-phenyl)-diphenylsilane, with aromatic diamines containing one or two phenylquinoxaline rings separated by a flexible bridge such as ether or methylene. These polymers were easily soluble in polar aprotic solvents such as N -methylpyrrolidinone (NMP) and dimethylformamide (DMF) and showed high thermal stability with decomposition temperature being above 450°C and glass transition temperature in the range of 260–304°C. Polymer solutions in NMP were processed into thin flexible films which exhibited very smooth surfaces, free of pinholes when studied by atomic force microscopy. The free-standing films showed a dielectric constant in the range of 3.6–3.7.

Thermostable Polymers Containing Phenylquinoxaline and Other Heterocyclic Units

Abstract Thermostable heterocyclic polymers containing phenyl-substituted quinoxaline and both amide and imide units have been synthesized by low-temperature solution polycondensation of diaminophenyl-quinoxalines with diacid chlorides of certain aromatic acids containing preformed imide rings. Also, copolymers have been obtained in which a mixture of diaminophenylquinoxaline and diaminooxadi-azole or diaminobenzimidazole was used in the reaction with the same diacid chlorides. The thermal stability and the electrical insulating properties of these products are discussed and compared with related heterocyclic polymers.

Highly fluorinated poly(1,3,4-oxadiazole-ether)s. structural, optical and dielectric characteristics

New fluorinated poly(1,3,4-oxadiazole-ether)s were prepared by nucleophilic aromatic substitution technique of an activated aromatic difluorinated compound with a bisphenol containing three trifluoromethyl groups, namely 1,1-bis(4′-hydroxyphenyl)-1-(3′,5′-ditrifluoromethylphenyl)-2,2,2-trifluoroethane, 1, or with a mixture of 1 and 9,9-bis(4-hydroxyphenyl)fluorene. FTIR and NMR spectroscopy were used to confirm the structure of the polymers. The polymers were easily soluble in organic solvents and could be processed in flexible thin films. The film surfaces exhibited hydrophobic characteristics, as it was determined by contact angle measurements. The polymers had high thermal stability, up to 440xa0°C, and glass transition temperature in the range of 202–237xa0°C. They showed fluorescence in the blue region, both in solution and in solid state. The change in electronic absorption and emission spectra of one of the polymer in neat and binary solvent mixtures has been studied. Broadband dielectric spectroscopy was used to investigate the relaxation processes in polymers. The dielectric constant of the polymers was in the range of 2.84–2.96, at 100xa0°C and 10xa0kHz, and decreased with the increase of fluorine content.

Polybenzoxazinones and poly(benzoxazinone-phenylquinoxaline)s containing pendant imide groups

Abstract Polybenzoxazinones and poly(benzoxazinone-phenylquinoxaline)s containing pendant imide groups have been synthesized by cyclopolycondensation of diacid chlorides which contain preformed imide rings, with 3,3′-dicarboxy-4,4′-diaminodiphenyl-methane or with mixtures of the latter with a bis(amino-phenylquinoxaline). The low temperature solution polycondensation technique afforded poly(amic-acid)s in the first step, which underwent thermal or chemical cyclodehydration, in the second step. The cyclodehydration process of the poly(amic-acid)s has been studied by infrared, thermogravimetric and differential scanning calorimetry analyses. The solubility, thermal stability and glass transition temperature of these polymers have been studied and compared with related heterocyclic polymers that have been previously reported.

New Poly(arylene ether sulfone)s Containing Phenolphthalein and Fluorene Moieties in the Main Chain

New poly(arylene ether sulfone)s have been synthesized by solution polycondensation reaction of 2,4-bis[(4-chlorophenyl)sulfonyl]-1-(phenylthio)benzene)] with 4,4-(9-fluorenylidene) bisphenol (FBP) and phenolphthalein (PP). The chemical structure of the polymers was confirmed by using both spectroscopical (FTIR, 1H-NMR) and elemental analysis methods. All the polymers were soluble in aprotic dipolar solvents. The thermal properties were investigated by differential scanning calorimetry and thermogravimetric analysis, and they, were discussed in connection with the chemical structure of the polymers. The investigation of optical properties by photoluminescence spectroscopy revealed that all the polymers displayed one emission peak in the blue domain beetwen 449 and 460 nm.

Aromatic Polyesteramides Containing Phenylquinoxaline Units

New thermostable polymers containing phenyl substituted quinoxaline and both amide and ester groups have been synthesized by low temperature solution polycondensation of diaminophenylquinoxalines with diacid dichlorides containing preformed ester linkages. The thermal stability as well as electrical insulating properties of these polymers are discussed and compared with related polymers previously reported.

New Sulfonated Polyethers and Polynaphthylimides based on TNT Derivatives

New sulfonated and non-sulfonated monomers — dinitro and diamino compounds — were prepared on the basis of 1,3,5-trinitrobenzene (TNB) which is the demethylation product of 2,4,6-trinitrotoluene (TNT). The sulfonated dinitrocompounds interacted with different binuclear bis-phenols under the conditions of aromatic nucleophilic nitrodisplacement reactions. Polyethers of moderate molecular weights were prepared on the basis of dinitrocompound containing electron-withdrawing 3,5-dinitrodiphenyl sulfone-4′-sulfonic acid “bridging” groups. Copolymers and blends with other sulfonated polymers were prepared to improve the film-forming properties of the polyethers developed on the basis of 3,5-dinitrodiphenyl sulfone-4′-sulfonic acid. High molecular weight sulfonated polynaphthylimides were prepared by the interaction of sulfonated diamine containing electron-donating ether group — 3,5-diaminodiphenyl ether-4′-sulfonic acid — with bis(naphthalic anhydride)s. The sulfonated polyethers and polynaphthylimides thus obtained contain sulfonic acid groups in the side chains.