Synthesis and characterization of aliphatic aromatic polyamides containing pyridine and methylene spacer group in polymer backbone

Abstract

Thermally stable and organo-soluble polyamides synthesized by polycondensation reaction of novel diacid monomer, 2,2'-[pyridine-2,6-diylbis(oxy-4,1-phenylene)]diacetic acid with various commercially available aromatic diamines such as Pyridine-2,6-diamine, 4-(4-aminophenylsulfonyl) benzenamine, 4-(4-aminobenzyl)benzenamine and 4-(4-aminophenoxy)benzenamine by using Yamazaki’s direct phosphorylation method. A 2,2'-[pyridine-2,6-diylbis(oxy-4,1-phenylene)]diacetic acid as a new compound containing methylene linkage and the heteroaromatic unit was successfully prepared by a displacement reaction. The resulted polymers show excellent thermal stability, good solubility in an aprotic polar solvent and inherent viscosities between 0.65 and 0.82 dL g−1. X-ray diffraction of all these polyamides shows amorphous nature. Polyamides showed glass-transition temperatures in the range of 193–199 °C indicates that polymers are easily processable. Thermogravimetric analysis of the polyamides indicated a 10% weight loss (T 10%) in the temperature range of 460–518 °C and char yields at 800 °C under nitrogen atmosphere in the range of 50–65% depending on the diamine monomer used for the synthesis polyamides. The structure-property correlation among these polyamides were discussed. The limiting oxygen indexes of all polyamides are more than 37.87, thus such type polymers of can act as flame retardant materials. These polyamides will be useful for high-performance applications.