Novel soluble and heat-resistant polyamides derived from 4-(4-diphenylphosphino) phenyl-2,6-bis(4-aminophenyl)pyridine and various aromatic dicarboxylic acids

Abstract

New diamine, 4-(4-diphenylphosphino)phenyl-2,6-bis(4-aminophenyl)pyridine, was prepared, and the related polyamides (PAs) bearing 2,6-diphenylpyridyl units and pendant diphenylphosphinophenyl groups were synthesized by direct polycondensation of this diamine and various aromatic diacids in N-methyl-2-pyrrolidinone (NMP) using triphenyl phosphite and pyridine as condensing agents. The resulting PAs with inherent viscosities of 0.78–1.06 dL g−1 are readily soluble in polar aprotic solvents such as NMP, N, N-dimethylacetamide, and dimethylsulfoxide as well as less polar solvents such as m-cresol and pyridine. All the PAs are amorphous and could be solution-cast into transparent, flexible, and tough films, which have tensile strengths of 68.2–88.8 MPa, tensile moduli of 1.9–2.4 GPa, and elongations at break of 5.4–10.3%. These polymer films also exhibit high optical transparence with the UV cutoff wavelength in the 361–412 nm range. These PAs display glass transition temperatures of 316–332°C, 10% mass loss temperatures of 524–553°C, and more than 48% residues at 800°C in nitrogen, respectively. Their high char yields and good limited oxygen index values ranging from 39 to 44 indicate the prepared PAs show good thermal stability and flame-retardant property.

Progress in the chemistry of functional aramids properties

“…Zhang et al in 2020, [97] synthesized PAs bearing diphenyl 2,6-pyridne units and diphenyl phosphinophenyl unit (Scheme 20, P20).…”

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

“…[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. 31,32 It is well known that copolymerization of rigid plus flexible monomers has been considered as an effective approach to obtain copolyamides with excellent comprehensive properties to meet specific processing and other requirements.…”

New fluorinated poly(pyridine amide)s derived from 2,6-bis(4-iodophenyl)-4-(4-trifluoromethylphenyl)pyridine by C–N coupling reaction

“…On the other hand, it has been demonstrated that the polyamides containing pyridine heterocyclic units in the main chain possess excellent thermal stability and mechanical property at elevated temperature due to the symmetry and aromaticity of the pyridine ring, as well as the polarization of nitrogen atom in pyridine. [30][31][32][33][34][35][36] Nevertheless, to the best of our knowledge, there are few reports on the synthesis of pyridine-containing polyamides via C-N coupling reaction using organometallic catalysts so far. In order to further develop new processable high performance polyamides and explore their preparation methods, we here report the preparation of new poly(pyridine amide)s containing 2,6-diphenyl-4-(4-trifluoromethylphenyl) pyridine moieties in the main chain by palladium catalyzed the carbonylation polycondensation of 2,6-bis(4-iodophenyl)-4-(4-trifluoromethylphenyl)pyridine and primary aromatic diamines with carbon monoxide, and their general properties such as solubility, thermal stability, crystallinity and optical transparency were investigated.…”