Synthesis and Characterization of Aromatic Poly(azomethine ether)s with Different meta- and para-Phenylene Linkage Contents

Abstract

New aromatic poly(azomethine ether)s (PAMEs) bearing different meta- and para-phenylene linkage ratios in the main chains were synthesized via solution polycondensation reactions of terephthalaldehyde and/or isophthaldehyde with 3,4′-diaminodiphenyl ether. The molecular structures, thermal stability, thermo-mechanical and optical properties of the synthesized PAME homopolymers and copolymers were investigated by using FT-IR, TGA, DMA, and UV-visible/ fluorescence spectroscopy, respectively. The synthesized PAMEs were characterized to be thermally stable up to ~400 °C under nitrogen or air atmosphere and to have high char residues of above 55 % at 800 °C under nitrogen condition. The DMA data revealed that the glass transition temperatures of PMAEs are in the range of 150–200 °C, depending on the relative contents of meta- and para-phenylene linkages. The maximum absorption wavelength of transparent yellowish PAME films was detected at 410±10 nm. In addition, all PAME films exhibited a broad visible emission band at 500–800 nm and two infrared emission bands at 800–1400 nm. The synthesized PAMEs with high thermal stability and thermo-mechanical performance can be thus used as functional polymeric materials for technical fibers, optoelectronic films, and carbon fiber precursors.