Synthesis and characterization of novel thermally stable aromatic and semiaromatic polyamides derived from thiourea-based flexible diacid dichlorides

摘要

New diacid dichlorides bearing phenyl thiourea groups were prepared by a facile synthetic approach and characterized using spectroscopic and elemental analyses. A series of novel aromatic and semiaromatic polyamides were prepared via a condensation route from the synthesized diacid dichlorides with 4,4'-oxydianiline. The polymers were characterized by FT-IR, ~1H NMR, ~(13)C NMR, and their physical properties, including their solution viscosities, solubilities and thermal properties, were studied too. Polyamides with phenyl thiourea moieties in the backbone showed good solubilities in amide solvents such as DMAc, DMF, DMSO, and NMP. All of the synthesized polymers had η_(inh) values of 0.042-0.053 dm~3/g, and were obtained in quantitative yield. GPC measurements of the synthesized polyamides indicated M_w values of 64,759-86,172. The crystallinity of the polymers was evaluated via their X-ray diffraction patterns. Their glass transition temperatures were found to be 218-229 °C. Furthermore, thermogravimetric analysis indicated that the polymers were thermally stable in the range 300-398 °C in a N2 atmosphere.