Rapid Postgrafting Reaction to Prepare Quaternized Polycarbazoles

• Published in: ACS macro letters 2024-01, Vol.13 (1), p.28-33
• Main Authors: Adhikari, Santosh, Matanovic, Ivana, Leonard, Daniel, Klein, Jeffrey M., Agarwal, Tanya, Kim, Yu Seung
• Format: Article
• Language: English
• Subjects: Anions; Aromatic compounds; Elimination reactions; Energy Sciences; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Monomers; Polymers
• ISSN: 2161-1653; 2161-1653
• DOI: 10.1021/acsmacrolett.3c00688

We report a rapid postgrafting reaction to prepare alkyl ammonium functionalized polycarbazoles from a commercially available monomer. This novel synthetic approach provides benefit to preparing the high molecular weight quaternized polycarbazoles within 1 h of Friedel–Crafts polycondensation, avoiding the synthesis and purification step to prepare a functionalized monomer. The postgrafting reaction produces hexyl alkyl ammonium functionalized polycarbazole with 100% grafting degree. However, the postgrafting reaction produced only 60% grafting with propyl alkyl ammonium due to the competitive elimination reaction because of the higher acidity of β-hydrogen in the propyl alkyl group resulting from the proximity of the bromide and ammonium groups. The hexyl alkyl ammonium functionalized polycarbazole has a high hydroxide conductivity of 103 mS cm–1 at 80 °C and showed excellent alkaline stability with less than 3% loss of ion group after 1 M NaOH treatment at 80 °C for 500 h. This study highlights that the postgrafting reaction provides a pathway for the scale-up synthesis of quaternized aryl ether-free polyaromatics.