New fluorinated aromatic polyamides based on N,N-bis(4-carboxyphenyl)-4-trifluoromethylaniline

Abstract

A new aromatic diacid monomer, N, N-bis(4-carboxyphenyl)-4-trifluoromethylaniline, was synthesized by the substitution reaction of 4-trifluoromethylaniline with 4-fluorobenzonitrile, followed by alkaline hydrolysis of the dinitrile intermediate. Several polyamides with 4-trifluoromethyltriphenylamine moieties were prepared from the diacid and various aromatic diamines via the direct phosphorylation polycondensation. All the polyamides were amorphous and readily soluble in many polar organic solvents such as N, N-dimethylacetamide and N-methyl-2-pyrrolidone, and could be solution-cast into transparent, tough, and flexible films with good mechanical properties. They exhibited good thermal stability with glass transition temperatures of 260–330°C, 10% weight-loss temperatures above 500°C, and char yields higher than 60% at 800°C in nitrogen. These polymers had low dielectric constants of 3.35–3.72 (100 Hz), low water uptake of 1.80–2.60%, and high transparency with an ultraviolet–visible absorption cutoff wavelength in the range of 378–390 nm. Cyclic voltammograms of the polyamide films cast onto an indium-tin oxide–coated glass substrate exhibited a reversible oxidation redox coupled with oxidation half-wave potentials ( E 1/2) of 0.95–1.04 V versus silver/silver chloride in an acetonitrile solution.

Synthesis and characterization of new aromatic copoly(ether amide)s bearing 4-trifluoromethylphenyl-2,6-diphenylpyridyl moieties in the main chain

“…Among them, incorporation of fluoroalkyl groups, especially 4-trifluoromethyl, has been demonstrated to afford polyamides with desirable solubility, thermal stability, dielectric, and optical properties. [21][22][23][24][25] On the other hand, it has been reported that the polyamides containing pyridine heterocyclic units in the main chain possess excellent thermal stability and mechanical property at elevated temperature because of the symmetry and aromaticity of the pyridine ring, as well as good solubility in organic solvents owing to the polarizability resulted from the nitrogen atom in pyridine. [26][27][28][29][30] Recently, we have described the synthesis of a series of soluble fluorinated polyamides containing 4-trifluoromethylphenyl-2,6-diphenylpyridyl moiety in the macromolecule main, showing acceptable thermal properties with high glass transition temperatures up to 320°C, good optical properties and low dielectric constants.…”

Heteroaromatic Polyamides with Improved Thermal and Mechanical Properties

“…The value for aromatic polyamides is 30–32% and 28–30% for meta - and para -aramids, respectively. Polymers with flame retardant properties commonly have halogens in their formulation [ 7 , 8 , 9 , 10 ].…”

“…In relation to the mechanical properties, recent efforts towards their improvement include the use of phthalazinone moieties [ 13 ], fluorine-containing monomers [ 6 , 14 ], cyano groups [ 15 ], bulky xanthene groups [ 8 ] or 4-aryl-2,6-diphenylpyridine moieties [ 16 ] , in the polymer structure. The crosslinking of polymeric chains in aramids leads to polymers with improved thermal and mechanical properties, as demonstrated in some works [ 17 , 18 ].…”