Summary: A kind of novel dibromocarbazole monomer bearing three alkyl chains was prepared. Two strategies were developed to improve the solubility and molecular weight of carbazole polymers. One was the polymerization of N-octyl-2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)carbazole with the alkylated dibromocarbazole. Another one was the polymerization of N-octyl-2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)carbazole with N-octyl-3,6-dibromocarbazole. All the polymerizations were carried out under palladium-catalyzed Suzuki polycondensation (SPC) conditions. Through using carbazole monomer bearing three alkyl chains to polymerize, we have successfully boosted the number-average molecular weight of 2,7-linked carbazole polymers from not more than 5 to 67 kDa. The high-molecular-weight polymers were obtained in high yields and displayed good solubility in common organic solvents. Their optical, electrochemical, and thermal properties were also reported.
Preparation of carbazole polymers by Suzuki polycondensation.