Synthesis and characterization of new poly(ester-imide)s based on 1,3-bis[4,4′-bis(trimellitimido) phenyl]-2-propenone and aromatic diols

Abstract

Six new poly(ester-imide)s 9a–f were prepared by the rapid polycondensation reaction of 1,3-bis[4,4′-bis(trimellitimidoyl chloride) phenyl]-2-propenone 7 with several aromatic diols 8a–f using a domestic microwave oven in the presence of a small amount of a polar organic medium, such as o-cresol. The polycondensation reaction proceeded more rapidly than solution polycondensation and was almost complete within 13 min, giving a series of poly(amide-imide)s in high yield with inherent viscosities ranging from 0.42 to 0.62 dL/g. All the above polymers were fully characterized by elemental analysis, viscosity measurements, solubility test, FTIR spectroscopy, differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA and DTG). 1,3-Bis [4,4′-bis(trimellitimidoyl chloride) phenyl]-2-propenone 7 was synthesized by a four-step reaction. Initially, 4-nitro benzaldehyde 1 was reacted with 4-nitro acetophenone 2 in acetic anhydride to form 1,3-bis(4-nitro phenyl)-2-propenone 3. The dinitro 3 was then reduced to the diamine 4 using sodium sulfide. A condensation reaction of one equimolar of diamine 4 with two equimolars of trimellitic anhydride 5 in a mixture of acetic acid and pyridine (3:2) led to the formation of 1,3-bis[4,4′-bis(trimellitimido) phenyl]-2-propenone 6. Finally the diacid 6 was converted to 1,3-bis[4,4′-bis(trimellitimidoyl chloride) phenyl]-2-propenone 7 by a reaction with thionyl chloride.