Synthesis and characterization of novel photoactive, thermally stable, and organosoluble polymers based on carbazole and imidazole derivatives in the main-chain

A series of novel polyamides (PAs) bearing substituted carbazole and imidazole rings in the main-chain were successfully synthesized via direct phosphorylation polycondensation between a new diamine, 5,5′-(9-octyl-carbazole-3,6-diyl)bis[4-phenyl-2-(4-amino-phenyl)-1H-imidazole], and various commercially available dicarboxylic acids. All intermediates and polymers were fully characterized by FTIR, NMR, and elemental analysis. These polymers were obtained in good yields with inherent viscosities of 0.42–0.55 dL/g and number average molecular weights (Mn) in the range of 24,875–31,720 g/mol molecular weight distribution (MWD=1.57–2.5). They exhibited excellent solubility in common polar aprotic organic solvents. These polymers had high glass transition temperatures (Tg)s (204–309 °C) and their temperatures at 10% weight loss (T10%) were found to be in the range of 404–511 °C in nitrogen. They exhibited strong UV absorption with maxima at 320–335 nm, and their photoluminescence (PL) efficiency was affected by their chemical structure; PL quantum yields were in the range of 4%–34%. The aliphatic PAs emitted blue light at λe.max=465 nm, while the aromatic PAs emitted green light at λe.max=490–510 nm in NMP solution.