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New type of aromatic polyamide/montmorillonite nanocomposites were produced using solution process in N-methyl-2-pyrolidone. Amide chains were synthesized from 4,4′-diaminodiphenyl sulfone and p-phenylenediacrylic acid in N-methyl-2-pyrolidone. The resulting nanocomposite films containing 5–15 mass % of organoclay were characterized for FT-IR, scanning electronmicroscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), optical transparency and water absorption measurements. The distribution of organoclay and nanostructure of the composites were investigated by (XRD) and SEM analyses. Thermogravimetric analysis indicated an increase in thermal stability of nanocomposites as compared to pristine polyamide. The percentage optical transparency and water absorption of these hybrids was found to be much reduced upon the addition of modified layered silicate indicating decreased permeability.

New poly(amide-imide)-montmorillonite reinforced nanocomposites containing Bis(4-N-trimellitylimido) diphenyl ether moiety in the main chain were synthesized by a convenient solution intercalation technique. Poly(amide-imide) (PAI) 4 was synthesized by the direct polycondensation reaction of Bis(4-N-trimellitylimido) diphenyl ether 3 with 4,4′-diamino diphenyl ether 2 in the presence of triphenyl phosphite (TPP), CaCl2, pyridine and N-methyl-2-pyrrolidone (NMP). Morphology and structure of the resulting PAI-nanocomposite films 4a and 4b with 10 and 20 mass% silicate particles respectively, were characterized by FT-IR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The properties of nanocomposites films were investigated by using Uv-vis spectroscopy, thermogravimetric analysis (TGA) and water uptake measurements.

Thiadiazole compounds including 3-hydroxy-4-substituted-1,2,5-thiadiazole are known as non-nucleoside inhibitors of HIV-1. Density functional calculations at the B3LYP/6-311++G(d,p) level were employed to determine the stability, tautomerism, and substituent effects of 1,2,5-thiadiazole, a widely used skin-whitening, antibrowning, and antibacterial agent, and its derivatives (4-NO2, 4-CN, 4-F, 4-H, 4-Me, 4-NH2), in the gas phase and solution using the polarizable continuum method model. Some selected IR frequencies, molecular parameters, charges on atoms, and dipole moment results were analyzed. [ABSTRACT FROM AUTHOR]

New optically active aromatic poly(amide-imide)s (PAIs) were prepared from newly synthesized N,N?-(bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracrboxylic)-bis-L-valine diacid (4) via polycondensation with various aromatic diamines. The diacid (4) was synthesized by the condensation reaction of bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (1) with L-valine (2) in acetic acid. All polymers were obtained in quantitative (high) yields with inherent viscosities of 0.24-0.36 dL/g. All of these polymers were highly organosoluble in solvents like N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), N,N'-dimethylacetamide (DMAc) and dimethylsulfoxide (DMSO) at room temperature and were fully characterized by means of NMR spectroscopy, FTIR spectroscopy, elemental analyses, inherent viscosity, solubility test, specific rotation and thermal properties of the poly(amide-imide)s were investigated using TGA/DTG. [ABSTRACT FROM AUTHOR]

Surface treated montmorillonite (MMT) was used to prepare nanocomposites with poly(amide-imide) (PAI) 5 by solution intercalation technique with various percent of organoclay (5–15 mass %). Surface modification of the MMT was performed with Cloisite 20A for ample compatibilization with the PAI matrix. The PAI 5 chains were produced through polycondensation of 4,4-diamino diphenyl sulfone 4 with N-trimellitylimido-L-alanine 3 in a medium consisting of triphenyl phosphite, N-methyl-2-pyrolidone (NMP), pyridine and calcium chloride. The PAI-Nanocomposites morphology and clay dispersion were investigated by X-ray diffraction (XRD) and Scanning electron microscopy (SEM). The effect of clay dispersion and the interaction between clay and PAI chains on the properties of PAI-Nanocomposites films were investigated by using UV-Vis spectroscopy, thermogravimetric analysis (TGA) and water uptake measurements. Thermal stability of nanocomposites increased relative to the neat polyamide with increasing organoclay content but water uptake of these materials decreased as compared to the neat polyamide indicating reduced permeability.