Synthesis and characterization of a novel rigid rod polymer based on 2,6-dihydroxyterephthalic acid and 2,3,5,6-tetraminopyridine

Poly- p -phenyleneterephthalamide (PPTA) is widely used in national defense, military industry, and aerospace. However, with weak compression resistance and twist resistance, development of PPTA is greatly impeded. In this work, a novel rigid rod polymer was synthesized by polycondensation of 2,6-dihydroxyterephthalic acid with 2,3,5,6-tetraminopyridine which have a large quantity of hydrogen bonds between these polymer chains which provide excellent thermal properties named poly [N-(2,5-diamino-6-[imino]-3-pyridyl)-4-formyl-2,6-dihydroxybenzamide] (PPDA). The structure of the polymers was characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The resulting showed that PPDA has good thermal stability and crystallinity, the maximum thermal decomposition temperature close to 900°C under the nitrogen atmosphere. At the same time, PPDA was insoluble in most organic solvents and exhibited good chemical stability. This indicated a superior performance over that of the poly(2,6-diimidazo(4,5-b:4′5′-e)pyridinylene-1,4(2,5-dihydroxy)phenylene). In addition, we can foresee that PPDA will play an important role in prospective surgery and aramid areas.