Poly(1,3,4-oxadiazole-imide)s containing dimethylsilane groups

Synthesis and photophysical study of new blue fluorescent poly(azomethine-1,3,4-oxadiazole)s containing dimethylamino groups

New aromatic polyazomethines were synthesized by polycondensation reaction of a diamine containing 1,3,4-oxadiazole ring, namely, 4,4′-diamino-4″-[2-(4-phenoxy)-5-(4-dimethylaminophenyl)-1,3,4-oxadiazole)]triphenylmethane, with terephthalic aldehyde or bis(4-formylphenoxyphenyl)fluorene, by using N-methyl-2-pyrrolidinone (NMP) as solvent. The polymers were easily soluble in polar solvents, such as NMP, N, N-dimethylacetamide, or chloroform, and showed high thermal stability with the initial decomposition temperature above 415°C and the temperature of 10% weight loss in the range of 450–460°C. They exhibited high char yield at 800°C in the range of 52–56%. Optical properties were studied by absorption and photoluminescence spectra. In solution, the polymers presented two absorption maxima in the ranges 273–278 and 330–346 nm and emitted violet-blue light in the range of 413–468 nm, depending on the solvent polarity. The Stokes shift and emission quantum yield values depend on the polymer structure and solvent polarity. The emission intensity in NMP solution was enhanced upon increasing the HCl concentration, while the absorption spectral profile was slightly influenced.

Synthesis and characterization of new soluble polyimides based on pyridine unit with flexible linkages

A series of new polyimides were synthesized by condensation of pyridine-bridged novel diamine monomers, bis(4-aminobenzoyloxy-3,5-dimethyl phenyl)-3′-pyridyl methane and 2,6-bis(2-amino-3-pyridyloxy)pyridine, with various aromatic anhydrides. The monomers and precursors were characterized by elemental analysis, Fourier transform infrared (FTIR), proton nuclear magnetic resonance (1H NMR), and carbon-13 nuclear magnetic resonance (13C NMR) spectroscopic techniques. The structure of the polymers were characterized by FTIR and 1H-NMR spectroscopy, and the physical properties of the polymers, including the glass transition temperature (in the range of 199–319°C), thermal and thermo-oxidative stability (10% weight loss temperature is in the range of 375–539°C in air and 403–542°C in nitrogen atmospheres), the char yield in the range of 37.91–56.65% at 800°C, solubility, solution viscosity (0.81–1.81), molecular weight data, optical properties, crystallinity, mechanical properties like tensile strength (86–102 MPa), elongation at break (12.5–16.5%), tensile modulus (1.2–1.8 GPa), and moisture absorption were also studied.

Silicon-containing oligomeric poly(imido-amides) with amino moieties. Synthesis, characterization and thermal studies

Silicon-containing oligomeric poly(imido-amides) (PIAs) were synthesized from dicarboxylic imido-acids containing a Si atom, which were obtained from dianhydrides, amino acids and p-aminobenzoic acid, were polymerized with the diamine bis(4-aminophenyl)diphenylsilane.

Copoly(1,3,4-oxadiazole-naphthylimide)s containing siloxane units in the main chain: synthesis and properties

This study was concerned with the synthesis and properties of new soluble copolyimides containing naphthalene, oxadiazole and tetramethyldisiloxane units. These copolyimides were prepared by two-step polycondensation reaction in solution of aromatic diamines containing preformed oxadiazole ring with a mixture 1 : 1 of naphthalene tetracarboxylic dianhydride and tetramethyldisiloxane- [1,3-bis(4′-phthalic anhydride)]. The structure of these polymers was confirmed by Fourier transform infrared and 1 H-NMR spectroscopy. The solubility, thermal stability and glass transition temperature of these copolyimides were measured and compared with those of related polyimides which do not contain siloxane groups. All these polymers emitted an intense blue color light upon irradiation with UV light. These copoly(oxadiazole-naphthylimide)s could be considered promising candidates for organo-soluble high-performance polymers for use in novel technological applications.