Synthesis and Characterization of a New Semi-Aliphatic Poly(amide-imide) and Evaluation of the Effect of Reaction Conditions

Abstract

Synthesis and characterization of a new aliphatic–aromatic poly(amide-imide) (PAI) with regular microstructure obtained via a two-step polymerization method was investigated. Firstly a fully imidized diimide-diacid (DIDA) intermediate was synthesized from trimellitic anhydride acid (TMA) and an aliphatic diamine with the ratio of 2:1; then, the corresponding PAI was prepared via a polycondensation reaction of the DIDA and an aromatic diisocyanate. Aprotic polar solvents like N-methyl pyrolidone (NMP) were used as the reaction solvent. Moreover, it was investigated how the regime of diamine addition affects the DIDA microstructure and the reaction yield. The effects of monomer ratio and its molecular structure, which determine the aliphatic/aromatic content of polymer backbone, on the structure and properties of the synthesized PAI were investigated. In addition, the effect of reaction solvent on polymer molecular weight through measurement of intrinsic viscosity was also studied. Fourier transform infrared (FT-IR) spectroscopy was used to determine the best reaction condition for DIDA synthesis, and nuclear magnetic resonance spectroscopy (1H- and 13C-NMR) was used to characterize the microstructure of synthesized polymers. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques were also used to characterize and study the polymer properties. As a result, it was shown that in the first step of the reaction merely a DIDA intermediate structure was synthesized without any side-reaction and subsequently a highly ordered co-polymer with amide–amide–imide–imide sequence was produced.