New soluble aromatic polyamides containing ether linkages and laterally attached p-terphenyls

Two series of new polyamides containing flexible ether linkages and laterally attached side rods (3a-i and 4a-i) were synthesized from 2',5'-bis(4-aminophenoxy)-[1,1';4',](n)]terphenyl (la) and 2',5'-bis(4-amino-2-trifluoromethylphenoxy)[1,1';4',1(n)]terphenyl (1b), respectively, with various aromatic dicarboxylic acids by the direct phosphorylation polycondensation. The polymers were produced with high yields and moderate to high inherent viscosities (0.41-0.97 dl/g) that corresponded to weight-average molecular weights (by size exclusion chromatography) of 47,000-65,000. Except for some polyamides that derived from rigid diacids, the obtained polyamides were readily soluble in aprotic polar solvents, such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc), and could afford flexible and tough films via solvent casting. The polymer films cast from DMAc solutions possessed tensile strengths of 85-106 MPa and initial moduli of 1.82-2.96 GPa. These polyamides showed glass-transition temperatures (T-g) in the range of 206263 C (by DSC) and softening temperatures (T-s) in the range of 211-253 degreesC (by TMA). Decomposition temperatures (T-d) for 10% weight loss all occurred above 400 degreesC (by TGA) in both nitrogen and air atmospheres. The polyamides 4a-i derived from trifluoromethyl-substituted diamine 1b generally showed a higher solubility, T-g and T-s but lower thermal stability as compared to the analogous polyamides 3a-i based on diamine 1a. (C) 2004 Elsevier Ltd. All rights reserved.