Synthesis and properties of new polyamides derived from 1,4-bis(4-aminophenoxy)-2,5-di-tert-butylbenzene and aromatic dicarboxylic acids

The diamine 1,4-bis(4-aminophenoxy)-2,5-di-tert-butylbenzene, containing symmetric, bulky di-tert-butyl substituents and a flexible ether unit, was synthesized and used to prepare a series of polyamides by the direct polycondensation with various aromatic dicarboxylic acids in N-methyl-2-pyrrolidinone (NMP) using triphenyl phosphite and pyridine as condensing agents. All the polymers were obtained in quantitative yields with inherent viscosities of 0.32-1.27 dL g(-1). Most of these polyamides, except IIa, IId, and IIe, showed an amorphous nature and dissolved in polar solvents and less polar solvents. Polyamides derived from 4,4'-sulfonyldibenzoic acid, 4,4'-(hexafluoroisopropylidene) dibenzoic acid, and 5-nitroisophthalic acid were even soluble in a common organic solvent such as THF. Most polyamide films could be obtained by casting from their N,N-dimethylacetamide (DMAc) solutions. The polyamide films had a tensile strength range of 49-78 MPa, an elongation range at break of 3-5%, and a tensile modulus range of 1.57-2.01 GPa. These polyamides had glass transition temperatures ranging between 253 and 276 degrees C, and 10% mass loss temperatures were recorded in the range 402-466 degrees C in nitrogen atmosphere. (C) 1998 John Wiley & Sons, Inc.