A novel pyridine-containing aromatic diamine monomer

4-［4-phenyl］-2

6-bis［4-(2-aminophenoxy)phenyl］pyridine (p

o-PAPP) was successfully synthesized respectively by nucleophilic substitution reaction

modified Chichibabin reaction and catalytic reduction with hydrazine monohydrate

2-hydroxyacetophenone and benzaldehyde.The aromatic diamine was employed to prepare a series of pyridine-containing polyimides by polycondensation with various aromatic dianhydrides in N

N -dimethylformamide (DMF) via the conventional two-step method.The inherent viscosities of the resulting poly(amic acid)s (PAAs) and polyimides (PIs) were in the range of 0.59~0.73 and 0.52~0.63 dL/g

respectively.The structure and performance of polymers were characterized by FTIR

solubility testing

DSC

XRD

TGA

UV-Vis and fluorescence spectroscopy.The results showed that there were characteristic peaks of polyimide around 1780

1720 and 1380 cm-1 in the FTIR spectra.The obtained PIs exhibited high solubility in common organic solvents

such as m-cresol

DMF

N

N -dimethylacetamide (DMAc)

dimethylsulfoxide (DMSO)

N -methylpyrrolidone (NMP)

tetrahydrofuran (THF) and chloroform (CHCl3).Meanwhile

flexible PI films were obtained

which had excellent thermal stability with the glass transition temperature (Tg) of 162.2~195.2℃ and the temperature at 10% weight loss of 444.2~467.5℃ in nitrogen atmosphere.The protonated polymer showed UV-Vis absorption in the region 200~360 nm and displayed strong fluorescence intensity (460 nm) in THF solution.