Synthesis and properties of novel aromatic polyamides derived from 2,2-bis[4-(4-amino-2-fluorophenoxy) phenyl]hexafluoropropane and aromatic dicarboxylic acids

A series of polyamides were synthesized by the direct polycondensation of 2,2-bis[4-(4-amino-2-fluorophenoxy)phennyl]hexafluoropropane with various commercially available dicarboxylic acids such as terephthalic acid, isophthalic acid, 5-t-butyl isophthalic acid, and 2,6-naphthalene dicarboxylic acid. The synthesized polyamides were soluble in several organic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, and chloroform, and they exhibited inherent viscosities of 0.42-0.59 dL/g. The polyamides exhibited weight-average molecular weights of up to 26,000, which depended on the exact repeating unit structure. These polyamides showed good thermal stability up to 440degreesC for a 10% weight loss in synthetic air. The polyamides synthesized from 5-t-butyl isophthalic acid and isophthalic acid exhibited glass-transition temperatures of 217 and 185degreesC, respectively (by differential scanning calorimetry) in nitrogen. The polyamides synthesized from terephthalic acid and 2,6-naphthalene dicarboxylic acid showed melting temperatures of 319 and 385degreesC, respectively. The polyamides films were pale yellow, with tensile strengths of up to 82 MPa, moduli of elasticity of up to 2.3 GPa, and elongations at break of up to 9%, which depended on the exact repeating unit structure. (C) 2003 Wiley Periodicals, Inc.