Synthesis and characterization of trifluoromethylated poly(ether–imidazole–imide)s based on unsymmetrical diamine bearing carbazole and imidazole chromophores in ionic liquids: Study of electrochemical properties by using nanocomposite electrode

New fluorinated polyimides based on 1,2-bis(4-aminophenyl)-4,5-bis(4-trifluoromethylphenyl)-1H-imidazole

A new aromatic unsymmetrical diamine containing imidazolyl and trifluoromethyl groups, 1,2-bis(4-aminophenyl)-4,5-bis(4-trifluoromethylphenyl)-1H-imidazole was synthesized. A series of novel fluorinated polyimides (PIs) were prepared by polycondensation of this diamine monomer with various aromatic dianhydrides via one-step process. The resulting PIs bearing inherent viscosities of 0.45–0.61 dL/g were amorphous and readily soluble in organic polar solvents such as NMP, DMF, DMAc, THF, and CHCl3. These new PIs exhibited good thermal stability with 10% weight loss temperatures of 530–560°C and char yields of 61–65% at 800°C in nitrogen, as well as good flame retardancy with limited oxygen index value of 40.6–42.8, and outstanding hydrophobicity with the contact angle of 85.2–93.5°. Meanwhile, all the obtained PIs exhibited low water uptake of 0.30–0.53%, strong UV-vis absorption in the range of 267–310 nm in DMF solution, and their films presented high optical transparency with a cut-off wavelength in the 355–392 nm range. Except for the PI film derived from pyromellitic dianhydride, the other PI films had the tensile strength in the range of 53.2–74.1 MPa, elongation at breakage of 6–15%, and tensile modulus of 1.0–1.5 GPa, respectively.

Photoconductive polyimides derived from a novel imidazole-containing diamine

A new diamine containing an imidazole structure, 4,4′-(4,5-diphenyl-1H-imidazole-1,2-diyl)dianiline (DIMA), was synthesized to prepare photoconductive polyimides (PIs) with four types of dianhydrides such as 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 4,4′-oxyduphthalic anhydride, 4,4′-(hexafluoroisopropylidene) diphthalic anhydride, and cyclobutane-1,2,3,4,-tetracarboxylic dianhydride, based on the fact that the imidazole ring is a useful n-type block with high electron-donating property and good thermal stability. The imidazole-containing diamine possesses high electron-donating properties due to the lone pair electrons at nitrogen, which affords a high hole-transport property. All the PIs prepared from DIMA were amorphous due to the large side group and kink structure of the diamine, optically transparent (transmittances of 92–98% at 450 nm), and exhibited high thermal stability (10% weight loss temperatures ranged 453–558°C).

Microwave assisted synthesis, spectroscopic studies and non linear optical properties of bis-chromophores

Bis chromophores were synthesized by the terephthalaldehyde with (4-nitrophenyl) acetonitrile/(4-flurophenyl) acetonitrile under microwave irradiation. Bis-chromophores were obtained in good to excellent yields. The structures of bis-chromophores were established by FT-IR, (1)H NMR, (13)C NMR, EI-MS and elemental analyses. Physical chemical properties such as singlet absorption, extinction coefficient, stokes shift, oscillator strength and dipole moment, were investigated by UV-Vis and fluorescence spectroscopy measurements. Further we also measured the nonlinear refractive index and nonlinear absorption coefficients of these compounds using the single beam z-scan technique with a cw argon ion laser at 514.5 nm at different concentrations in DMSO solvent. The third order nonlinear susceptibility was estimated from these measurements and it shows high nonlinearity. The high negative refractive index makes these compounds suitable for optical limiting application.

Preparation and properties of magnetic Fe3O4/poly(pyrimidine-amide) nanocomposites: selective polyamidation of a bis(amino-pyrimidine-diol) compound in an ionic liquid

This work reports the preparation of magnetic nanocomposite poly(pyrimidine-amide) (MNCPPA)s from interfacial reaction between multifunctional poly(pyrimidine-amide)s (PPAs) and epoxide functionalized magnetic Fe₃O₄ nanoparticles.