Synthesis of hyperbranched polyimides and polyamides using ortho-substituted asymmetric triamine

Hyperbranched polymers synthesized from A 2 and B 3 monomers typically exhibit high viscosity as their molecular weight increases. In this study, hyperbranched polyimides and polyamides with both high-molecular-weight and low-viscosity were successfully synthesized using 2,4-bis(4-aminophenoxy)aniline (2,4-triamine) and commercially available A 2 monomers. The unique reactivity of one amino group in 2,4-triamine—potentially highly reactive yet sterically protected during the early stages of polymerization—plays a key role in the formation of high-molecular-weight, low-viscosity hyperbranched polymers. Intramolecular cyclizations competed with propagation reactions, and its extent was found to depend on both the monomer structure and the monomer feed ratio. The resulting hyperbranched polyimides and polyamides exhibited high glass transition temperatures and excellent thermal stability. The introduction of electron-donating ortho-substituents in the B 3 monomer as a nucleophile provides a promising strategy for the efficient synthesis of high-molecular-weight and low-viscosity hyperbranched polymers from A 2 and B 3 monomers. • High-molecular-weight and low-viscosity hyperbranched polymers were synthesized using an asymmetric triamine and commercially available monomers. • The ortho-substituted triamine exhibited unique reactivity, favoring the formation of AB2 type compounds in the polymerization mixture. • Intramolecular cyclization proceeded concurrently with the propagation reaction.