Synthesis and characterization of thermostable polyamides from unsymmetrical diamines containing flexible ether linkage and different diarylimidazole pendants in ionic liquids

A series of aromatic poly(amide-ether) (PAE)s containing derivatives of imidazole heterocyclic ring and flexible ether linkages was synthesized from polymerization reaction of three new diamines with commercially available aromatic diacids by using two different methods of direct polycondensation: (1) By using triphenyl phosphite (TPP) as activating agent, NMP, pyridine (Py) and LiCl, and (2) by using combination of an ionic liquid (IL) and TPP which allowed to carry out PAEs synthesis without using Py, LiCl and NMP. Room temperature ILs bearing anions such as BF ₄ ^- , Br^-, Cl^-, and PF ₆ ^- with symmetrical 1,3-dialkylimidazolium cations have been prepared and used as polycondensation media. The polymers were obtained in good yields with moderate viscosity (0.47–0.68 dL/g) in a shorter time of reaction (2.5 h) in comparison with the PAEs obtained in NMP (12 h). All of these polymers were amorphous in nature, showed excellent solubility in amide-type polar aprotic solvents. These polymers showed good thermal stability with glass transition temperatures (T_g) between 212–355 °C and 10 % weight loss temperatures were recorded around 421 °C and 460 °C in air and N₂, respectively. These polymers showed blue flourescence emission in the range of 460–505 nm and can be candidate for applications in photoluminescent devices.