Direct Polycondensation of New Poly(amide-imide)s Containig N-(4- Carboxy phenyl) Trimellitimide By Using Triphenyl Phosphite

Introduction: Aromatic polyimides are heat resistant polymers that generally show excellent mechanical strength and stability. However, one of the drawbacks to the employment of these high performance polymers is the difficulty in processing due to their high melting temperatures or high glass transition temperatures. Copolycondensation is one of the possible ways for modification of polymer properties. Thus, for the processing of polyimides many copolyimides, such as poly(amide-imide)s, poly(sulfone-imide)s, poly (ether-imide)s, poly(ester-imide)s and other copolymers have been prepared. Aim: In this article, we describe synthesis and characterization a series of novel PAIs (5a-f) containing trimethylene and hydantoin segments between imide rings in the main chain by the direct polycondensation reaction of N-(4- carboxyphenyl)-trimellitimide (3) with six hydantoin derivatives (4a-f) in a medium consisting of N-methyl-2-pyrrolidone, triphenyl phosphite, calcium chloride and pyridine. Materials and Methods: All chemicals were purchased from Fluka and Merck Chemical Company. The 1 H-NMR spectrum (300 MHz) was recorded on a Bruker Avance 300 spectrometer (Germany). Fourier transform infrared (FT-IR) spectra were recorded on a Galaxy series FTIR 5000 spectrophotometer (England). Results: Six new poly(amide-imide)s (5a-f) were prepared by direct polycondensation reaction of N-(4-carboxyphenyl)-trimellitimide (3) with six different of 5,5-disubstituted hydantoin derivatives (4a-f) using triphenyl phosphate (TPP) and pyridine as condensing agents in N-methyl-2-pyrolidone (NMP) solution containing dissolved calcium chloride. The polycondensation reaction produced a series of novel poly(amide-imide)s (5a-f) in high yields with inherent viscosities between 0.26-0.62 dL/g. The resulted polymers were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis (TGA and DTG), solubility test and FT-IR spectroscopy. Conclusion: This work involved the synthesis and characterization of several new PAIs (5a-f) by direct polycondensation reaction of N-(4-carboxyphenyl)trimellitimide (3) with different 5,5-disubstituted hydantoin derivatives (4a-f) using TPP and pyridine as condensing agents in NMP solution containing dissolved calcium chloride. These new PAIs are soluble in various organic solvents and have good thermal stability. These properties could make these PAIs attractive for practical applications, such as processable highperformance engineering plastics.