New Poly(Amide-Imide)s Based on 1,3-Bis[4,4′-(Trimellitimido) Phenoxy] Propane and Hydantoin Derivatives: Synthesis and Properties

1,3-Bis[4,4′-(trimellitimido) phenoxy] propane (6) as a new monomer containing a trimethylene moiety was synthesized using a three-step reaction. First 1,3-bis[4,4′-nitrophenoxy] propane (3) was prepared by reaction of 4-nitrophenol 1 with 1,3-dibromo propane (2) in DMF. Then dinitro (3) was reduced to 1,3-bis[4,4′-aminophenoxy] propane (4) using a solution of sodium sulfite in ethanol. Finally, monomer (6) was prepared by reaction of one equivalent diamine (4) with two equivalents of trimellitic anhydride (5) in a mixture of acetic acid and pyridine (3:2). Then six new poly(amide-imide)s (8a - f) were synthesized through the polycondensation reaction of diacid (6) with six different derivatives of hydantoin (7a - f) in N-methyl-2-pyrrolidone, using triphenylphosphite and pyridine as condensing agents. The polycondensation produced a series of novel poly(amide-imide)s in high yields with inherent viscosities between 0.31 and 0.61 dl/g. The resulting poly(amide-imide)s were characterized by elemental analysis, viscosity measurements, thermogravimetric analysis (TGA and DTG), differential scanning calorimetry, solubility tests and FT-IR spectroscopy.