Synthesis and Characterization of Novel Aromatic Polyamides from 1,4-Bis(4-aminophenyl)-2,3-diphenylnaphthalene and Aromatic Dicarboxylic Acids

Abstract

ABSTRACT:A new highly phenylated diamine, 1,4-bis(4-aminophenyl)-2,3-diphenylnaphthalene, was synthesized in two steps starting from 2,5-bis(4-nitrophenyl)-3,4-diphenylcyclopentadienone. New aromatic polyamides containing tetraphenylnaphthalene unit were prepared by low temperature solution polycondensation of this diamine with various aromatic dicarboxylic acid chlorides. These polyamides had inherent viscosities of0.45---0.82 dlg-1 . Polyamides with m-phenylene moiety and flexible connecting group were soluble in various organic solvents such as N,N-dimethylacetamide and N-methyl-2-pyrrolidone, but those with rigid symmetric structures were soluble in only hot N,N-dimethylacetamide and N-methyl-2-pyrrolidone. The glass transition temperature of the polyamides ranged from 268 to 366°C, and the 10% weight loss temperatures were above soooc in air. KEY WORDSHigh Temperature Polymers I Soluble Aromatic Polyamides I 1,4-Bis(4-aminophenyl)-2,3-diphenylnaphthalene I Thermal Behavior I Aromatic polyamides are high thermal stability coupled with high crystallinity and hence high temperature application especially as fibers. 1 However, most wholly aromatic polyamides are difficult to fabricate because of low solubility and high melting temperature. Several attempts have been made to improve the solubility by modifying the structure without losing their good thermal stability. Aromatic polyamides having phenyl-pendant structures such as tetraphenylthiophene, 2 -5 tetraphenylfuran, 6 tetraphenylpyrrole, 7 tetraphenylethylene, 8 triphenylamine, 9 triphenylphosphine, 10 triphenylbenzene, 11 hexaphenylbenzene, 12 and tetraphenylquinquephenyl, 13 have high thermal stability and high solubility. We conducted the synthesis of a new diamine monomer, 1 ,4-bis( 4-aminophenyl)-2,3-diphenylnaphtalene and aromatic polyamides derived from it. This article deals with the synthesis and characterization of novel aromatic polyamides from this diamine and aromatic dicarboxylic acid chlorides. The properties of polyamides such as solubility and thermal behavior are also discussed.

Soluble aromatic poly(ether amide)s containing aryl‐, alkyl‐, and chloro‐substituted phthalazinone segments

“…However, commercially available aromatic polyamides, for example, Kevlar of DuPont, are insoluble in typical organic solvents and infusible before their decomposition because of their rigid, rodlike polymer backbone, which restricts their fabrication, processing, and application1 (to some extent). To overcome these shortcomings, considerable efforts have been directed toward the improvement of their solubility or melt processability via molecular design 2–4. Novel, soluble aromatic polyamides have been synthesized through delicate molecular design while maintaining their high‐performance characteristics 5.…”