Structural characterization and properties of organo-soluble polyimides, bismaleimide and polyaspartimides based on 4,4-dichloro-3,3′-diamino benzophenone

A novel chlorinated diamine monomer with keto group, 4,4'-dichloro-3,3'-diamino benzophenone (DADCB) was prepared through the nitration of dichloro benzophenone (DNDCB) followed by catalytic reduction with SnCl4 and HCl. Chlorinated polyimides (IVa-e) were synthesized from the above diamine with various commercially available dianhydrides via one-step and two-step methods. Polyimides IVa-e have inherent viscosity in the range 0.98-1.42 dL g(-1) in the one-step method and 0.70-0.95 dL g(-1) (thermal imidization) and 0.84-1.33 dL g(-1) (chemical imidization) in the two-step method. ne polyimides prepared by the one-step method and chemical imidization method exhibited excellent solubility, but those prepared via thermal imidization exhibited limited solubility. Polyimide films exhibited tensile strength 95-121 MPa, percentage elongation 8-13% and tensile modulus 1.6-2.4 GPa. The T, of the polyimides are in the range 272-297 degrees C and T-10 values are in the range 510-542 degrees C in N-2 and 460-498 degrees C in air with more than 40% char yield at 800 degrees C in N-2 atmosphere. The prepared polyimides have cutoff wavelength in the range of 360-398 nm and percentage transmittance at 500 nm is in the range 80.9-94.2%. The dielectric constant of the polyimide films are in the range of 2.90-3.82 at 1 kHz and 2.85-3.68 at 10 kHz with moisture absorption in the range 0.38-0.88%. Bismaleimide (BMCB) was also synthesized using the synthesized diamine and maleic anhydride and further treated with various diamines to form linear polyaspartimides and their properties such as viscosity, solubility and thermal properties were also studied.