Novel thermally stable and organosoluble aromatic polyamides with main chain phenyl-1,3,5-triazine moieties

The syntheses and properties of phenyl-1,3,5-triazine functional aromatic polyamides are described. From 2,4,6-trichloro-1,3,5-triazine (1), an aromatic diacid, namely 4-(4,6-diphenyl-1,3,5-triazin-2-yl)benzoic acid (6), was prepared by a three-step reaction in satisfactory yields. A model reaction of 6 with aniline (7) was carried out to determine feasibility of amidization. Aromatic poly(phenyl-1,3,5-triazine amide)s (10a-10e) with inherent viscosities ranging from 0.28 to 1.26 dL/g were synthesized from Yamazaki phosphorylation polycondensation of 6 with aromatic diamines (9a-9e). The reactions were conducted in N-methyl-2-pyrrolidone (NMP) to yield high-molecular-weight amorphous polymers in essentially high yields. All polymers are readily soluble in NMP and N,N-dimethylacetamide (DMAc) at room temperature, and formed transparent films from their solution. The films exhibit good mechanical properties with tensile strengths of 71.5-94.7 MPa, elongations at break of 6.1-10.0%, and initial moduli of 2.3-2.8 GPa except that of 10a is slightly brittle. These polymers have high glass transitions from 311 to 330 °C, depending on the aromatic diamines used in the polycondensation, and they demonstrate excellent thermal stabilities in excess of 440 °C (5% weight loss in air). Isothermal TGA measurements reveal that the obtained benzene-1,3-diamine-based poly(phenyl-1,3,5-triazine amide) (10b) belongs to the most superior class of heat resistant polymers such as polyamide Kevlar®.