Ionic liquids in the synthesis of high-performance fluorinated polyamides with backbones containing derivatives of imidazole and carbazole rings

Abstract

A series of new organosoluble poly(amide-ether-imidazole)s with different functional groups, such as flexible ether linkages, substituted imidazole and carbazole rings, and electron withdrawing CF3 groups, were synthesized from a new diamine and various dicarboxylic acids using two methods: (1) direct polycondensation with triphenyl phosphite (TPP) as an activating agent, N-methyl-2-pyrrolidone (NMP), pyridine (Py) and LiCl; and (2) direct polycondensation using ionic liquids (ILs) and TPP without Py, LiCl or NMP. Room temperature ILs containing anions such as Br−, BF−4 and PF−6 with symmetrical 1,3-dialkylimidazolium cations were prepared and used as polycondensation media. The polymers were obtained with good yields in ILs with moderate viscosities (0.34–0.62 dl g−1) in a shorter reaction time (2.5 vs 12 h) than in NMP. All of the polymers were amorphous in nature and showed excellent solubility in amide-type polar aprotic solvents. They showed good thermal stability with glass transition temperatures (Tg) between 162 and 303 °C and 10% weight loss temperatures of 388 and 421 °C in O2 and N2 atmospheres, respectively. These polymers showed blue fluorescence emission upon irradiation with ultraviolet light and are candidates for applications in electroluminescent devices.