Inexpensive synthesis of 1,4-bis(4-aminophenoxy)-2- (6-oxido-6H-dibenz <c,e> <1,2> oxaphosphorin-6-yl) phenylene and its oxygen-plasma resistant polyamides

Inexpensive synthesis of diamine, 1,4-bis(4-nitrophenoxy)-2-(6-oxido-6H-dibenz <c,e> <1,2> oxaphosphorin-6-yl) phenylene was revealed in this work. Based on the diamine, a series of organosoluble polyamides were prepared by direct polycondensation of the diamine with various aromatic diacids using triphenyl phosphite and pyridine as condensing agents. The number–average molecular weights of the resulting polyamides range from 4.2 × 104 to 10.5 × 104 g/mol, and the weight–average molecular weights are in the range of 7.5–28.2 × 104 g/mol. The Tgs of these polyamides range from 210 to 255 °C by dynamic mechanical analysis. The resulting polyamides are tough and flexible with tensile strength, elongation at break and moduli range from 84 to 101 MPa, 4.8–7.0%, and 2.36–3.22 GPa, respectively. The degradation temperatures (Td 5%) and char yields at 800 °C in nitrogen range from 460 to 486 °C and 59–68 wt%, respectively. The cutoff wavelength of these polyamides falls in the range of 345–366 nm, showing a very light color characteristic. In addition, these polyamides display good oxygen plasma resistance.