Synthesis and properties of novel aromatic polyamides containing 2-methyl-4,5-oxazolediyl structure

Novel aromatic polyamides having 2-methyl-4,5-oxazolediyl units in the main chains were synthesized. The polyamides were prepared from 4,5-di(4-aminophenyl)-2-methyloxazole (DAPMO) and/or 4,4'-[4,5-(2-methyl)oxazole]dibenzoic acid (MODBA) by the direct polycondensation method. The polyamides, the inherent viscosities of which ranged from 0.64 to 1.95 dl g(-1), were obtained almost quantitatively. The polyamides indicated high thermal properties: glass transition temperatures were found in the range between 280 and 354 degrees C, and thermal decomposition temperatures ranged from 376 to 421 degrees C. The polyamides exhibited good solubility in many organic solvents such as m-cresol, N,N-dimethylacetamide, 1-methyl-2-pyrrolidone, N,N-dimethyl formamide and cone. H2SO4 at 2.0% (w/v). All the polyamides showed amorphous nature. The introduction of the zigzag, rigid and polar 2-methyl-4,5-oxazolediyl structure into the main chains of polyamides was effective in improving the solubility without lowering the high thermal properties. (C) 1997 Elsevier Science Ltd. All rights reserved.