1H NMR Analysis of Aromatic Polyamide in N-methyl-2-pyroridone Solution

An aromatic copolyamide was prepared from terephthaloyl chloride (TPC), 1, 4-phenylenediamine (PPDA), and 3, 4′ -diaminodiphenyl ether (3, 4′ -DAPE), with a TPC/PPDA/3, 4′ -DAPE monomer mole ratio of 50/25/25. Its structure was analysed by 1H NMR in the N-methy1-2-pyroridone (NMP) solution. The analysis mainly focused on the formation of the hydrogen bond related with gelling, because the polymer solution lost its liquidity and provided a gel by heat treatment for 7 days at 180°C. The analysis of H-D exchange data using D2O and two-dimensional NOESY spectrum showed that the hydrogen bonds were formed mainly between 1, 4-phenyleneterephthalarnide units by heat treatment. Since these acted as bridging sites, a physical gel was formed. Further, Inductively Coupled Plasma Spectrometry showed that the concentration of neutral salt existing in the gel fell to about half of the normal concentration. The fall in the concentration of neutral salt existing in the polymer was related with the gelling.