A series of new polyimides were synthesized by condensation of pyridine-bridged novel diamine monomers, bis(4-aminobenzoyloxy-3,5-dimethyl phenyl)-3 0 -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 ( 1 H NMR), and carbon-13 nuclear magnetic resonance ( 13 C NMR) spectroscopic techniques. The structure of the polymers were characterized by FTIR and 1 H-NMR spectroscopy, and the physical properties of the polymers, including the glass transition temperature (in the range of 199-319 C), thermal and thermooxidative 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.

Novel polyimides containing two long/bulky aromatic pendent chains and their nanocomposites with aromatic amine functionalized silica were prepared from a new diamine bis(4-aminophenyl)bis{3,4[(4-(8-quinolyloxymethyl carbonyl)phenoxy)]}methane.

Summary: A series of new polyimides were obtained by the polycondensation reactions of the three diamines containing pyridine and anthracene units with various aromatic tetra carboxylic dianhydrides via both two-step and one-step methods. The precursors and monomers were characterized by elemental analysis, FT-IR, 1 H-NMR and 13 C-NMR techniques. The structure of the polyimides was confirmed by FT-IR, and 1 H-NMR spectroscopy, inherent viscosity and molecular weight measurements. All the polyimides are soluble in aprotic solvents such as NMP, DMF, DMAc and DMSO. These polyimides exhibit T g in the range of 213-317 C and 10% weight loss (T 10 ) takes place in the range of 414-531 C in N 2 401-521 C in air and the char yield varies between 38-54%. The polymer films have tensile strength in the range of 84-110 MPa, elongation at break in the range of 11.2-13.8% and tensile modulus in the range of 1.1-1.4 GPa and low moisture absorption (0.87-1.16). All of these new polymers show excellent thermal stability and the polyimide films have good mechanical properties.

A new diamine monomer having ether and azomethine linkages in the long pendent group was synthesized. New polyimide was prepared by reacting the new diamine with BTDA and nanocomposites were prepared with silicon dioxide as nanofiller. SEM analysis shows a uniform distribution of the nanopowder in the polyimide matrix. TGA shows that the polyimide and nanocomposites have good thermal stability with the T10% values varying between 440 and 458°C. DSC analysis shows Tg values between 210 and 230°C. The neat polyimide shows high elongation at break and stretchability (260%) but low tensile strength. The nanocomposites of polyimide show lower elongation at break but have improved tensile strength. The chemically imidised polyimide shows good solubility in solvents like N, N‐dimethyl formamide, N, N‐dimethyl acetamide, and N‐methyl 2‐pyrrollidone. POLYM. COMPOS., 40:832–843, 2019. © 2018 Society of Plastics Engineers