A new aromatic diamine monomer

-bis(4-amino-3

5-dimethylphenyl)phenylmethane (BADP)

was synthesized via a straightforward one-step procedure with high yield.FTIR and 1H-NMR were employed to confirm the designed structure.In order to maintain the excellent thermal properties and improve the solubility of polyimides

a series of aromatic polyimides were successfully synthesized via one-step polymerization method in anhydrous N-methyl-2-pyrrolidone (NMP) by a reaction of 2-(4-aminophenyl)-5-aminobenzimidazole (BIA)

the synthesized BADP and one of four dianhydrides (PDMA

BPDA

BTDA and ODPA).The structures of copolyimides were confirmed by FTIR

showing the characteristic peaks of polyimides at 1780

1720 and 725 cm-1.The UV-Vis measurements indicated that the cut-off wavelengths were at 360~380 nm without consideration of relatively weak transmittance in the range of 310~360 nm.As we expected

the polyimides exhibit excellent solubility

and can be dissolved in normal solvents such as NMP

DMAc or CHCl3.The soluble polyimides show a relatively higher glass transition temperature (Tg 410℃) measured by dynamic mechanical analysis (DMA) and a high initial decomposition temperature (Td500℃) in TGA and more than 55 wt% residues at 900℃ under nitrogen atmosphere.Moreover

the tensile strength of polyimides is 61~100 MPa.The soluble polymers can be used as high performance resins or processed into high performance fibers.