Preparation and Characterization of New Aromatic Polyimides from 1,2,4,5-Benzene tetracarboxylic Acid Dianhydride and New Aromatic Diamines

Abstract

A series of new aromatic polyimides (Pi1 - Pi6) containing methylene unit, flexible ether
linkages (containing naphthalene rings), and Schiff-base linkages were prepared by solution
polycondensation reaction of 1,2,4,5-benzene tetracarboxylic dianhydride (BTDA) with new
various aromatic diamines using a standard two-stage process with thermal imidization of
poly(amic acid) films. The monomers were characterized by FT.IR, and some them by 1H. NMR.
The resulting polymers were characterized by means of FT.IR, 1H.NMR spectroscopy, and
solubility tests. All polyimides were readily soluble in polar aprotic solvents. The thermal stability,
melting temperature and glass transition temperature of these polyimides were measured using
differential scanning calorimetry (DSC). These polymers formed tough flexible films by solution
casting.