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A new series of polyimides having azomethine functionality in backbone was synthesized by two-steps polycondensation method. Five substituted aromatic diamines--N-(4-aminobenzylidene)-2chloro-6-methylbenzene-1,4-diamine (DA1), N-(4-aminobenzylidene)-2-methoxybenzene-1,4-diamine (DA2), N-(4-aminobenzylidene)-2-methylbenzene-1,4-diamine (DA3), N-(4-aminobenzylidene)-3-methylbenzene-1,4-diamine (DA4) and N,(4-aminobenzylidene)-2-hydroxybenzene-1,4-diamine (DA5)--were prepared and condensed with 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) to obtain poly(azomethine imide). All synthesized polyimides PI(1-5) were fully characterized by elemental analyses, FTIR, 1 H-NMR, having amorphous nature and are soluble in dmac, dmf, and dmso, m-cresol due to presence of azomethine functionality. The inherent viscosities and moisture absorption of all polyimides lie in the range of 0.65-0.85 dL gm −1 and 0.68-0.82% respectively. Thermal stability was assessed by 10% weight loss temperature and the degradation temperature of the resultant polymers falls in the ranges from 480-535 o C in nitrogen. The glass transition temperature was in the range of 225-330 o C. Due to above mentioned attractive properties, polyimidebased material are attractive for processable high-performance engineering plastics and starting material for fabrication of new polymers.

A new series of polyimides was synthesized by the condensation of monomers (azomethine-ether diamine, DA-1 and DA-2) with pyromelliticdianhydride (PMDA), 3,4,9,10-perylenetetracarboxylic dianhydride (PD) and 3,3′4,4′-benzophenonetetracarboxylic dianhydride (BD). The structural explications of monomers and polyimides was conducted by FT-IR, 1 H NMR and elemental analysis. All polyimides were found soluble in polar aprotic solvents and found to be semicrystalline in nature confirmed by XRD. The inherent viscosities were found in the range of 0.67-0.77 g/dl. %. Average molecular weight (M W ) and number average molecular weight (Mn) of the polyimides were found in the range of 5.72 × 10 5 g/mol-6.58 × 10 5 g/mol and 3.79 × 10 5 g/mol 4.11 × 10 5 g/mol respectively. The polyimides exhibited excellent thermal properties having a glass transition temperature T g in the range of 230-290°C and the 10% weight loss temperature was above 450°C. The values of thermodynamic parameters, activation energy, enthalpy and entropy fall in the range of 45.2-53.90 kJ/mol, 43.5-52.30 kJ/mol and 0.217 kJ/mol k to 0.261 kJ/mol k respectively.

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A series of six novel polyimides containing 3,6-di(4-carboxyphenyl)pyromellitic dianhydride were synthesized via two steps condensation method. Aromatic diamines monomers, 4-(4-aminophenoxy)-N-(4-(4-aminophenoxy)benzylidene)-3-chloroaniline (DA1), 4-(4-amino-3-methylphenoxy)-N-(4-(4-amino-3-methylphenoxy)benzylidene)-3-chloroaniline (DA2), 4-(4-amino-2-methylphenoxy)-N-(4-(4-amino-2-methylphenoxy)benzylidene)-3-chloroaniline (DA3) 4-(4-aminophenoxy)-N-(4-(4-aminophenoxy)benzylidene)-2-methylaniline (DA4), 4-(4-amino-3-methylphenoxy)-N-(4-(4-amino-3-methylphenoxy)benzylidene)-2-methylaniline (DA5), and 4-(4-amino-2-methylphenoxy)-N-(4-(4-amino-2-methylphenoxy)benzylidene)-2-methylaniline (DA6) were prepared and used to synthesize new polyimides by reaction with resynthesized 3,6-di(4-carboxyphenyl)pyromellitic dianhydride by using two-step condensation method. The inherent viscosities of polyimides range from 0.68–1.04 dL gm−1 and were soluble in polar solvents. Polyimides have excellent thermal stability by showing 10% weight loss temperature was above 450°C. Their glass transition temperatures lie in the range of 250–335°C. Wide-angle X-ray diffractometer investigations revealed the amorphous nature of polyimides. Therefore, these polymers can be a potential candidate as processable high performance polymeric materials.