SYNTHESIS OF A 1,3,5-TRIAZINE-CONTAINING AROMATIC DIACID MONOMER AND ITS SOLUBLE AROMATIC POLYAMIDES
Li, Bin; Wu, Sfei; Liu, JunL; Xiong, Shui; Tan, Haijun; Yu, GuiP; Pan, Cyue; Jian, Xigao
The synthesis, characterization and properties of phenyl-1,3,5-triazine functional monomers and aromatic polyamides are described. A novel aromatic diacid, namely 4,4'-(6-phenyl-1,3,5-triazine-2,4-diyl) dibenzoic acid (PTDA) was successfully prepared by a two-step reaction including Friedel-Crafts reaction and oxidation starting from 2,4-dichloro-6-phenyl-1,3,5-triazine (DCPT). Its chemical structure was characterized by H-1-NMR,FTIR, MS and Elemental analysis. Optimal conditions of the oxidation were chosen on the basis of the yield by using orthogonal experiments with respect to oxidizer content, solvent ratio, heating temperature and reaction time. The reaction, which was achieved at the temperature of 25 degrees C for 8 h with a CH3COOH/H2SO4 ratio of 10 and a CrO3/PTDA ratio of 4, gave the targeted product with a highest yield of 81.3%. A new aromatic polyamide (PPA) with an inherent viscosity of 0.49 dL/g was obtained by direct phosphorylation polycondensation of PTDA with benzene-1,4-diamine. The:obtained polymer possesses good solubility. It is readily soluble in N-methylpyrrolidone, N,N-dimethyl acetamide (DMAc) and sulfolane, and can be easily cast into transparent thin films. Such polymer exhibits glass transition temperature (T-g) up to 315 degrees C, and possesses excellent thermal and thermo-oxidative stability without significant weight loss up to temperatures of approximately 500 degrees C. Its decomposition temperature for 5% mass-loss is in excess of 493 degrees C in nitrogen and it retains 90% weight at round 520 degrees C. The obtained films exhibits attractable mechanical properties with tensile strengths of 82 MPa,elongation at break of 8.2% and initial moduli of 2.3 GPa.
