Regioselective RAFT–HDA: a new approach to synthesize hyperbranched polymers with precise topology control†

This study introduces a novel approach combining reversible addition–fragmentation chain transfer (RAFT) polymerization and hetero-Diels–Alder (HDA) reactions to efficiently synthesize hyperbranched polymers (HBPs) with controlled topology. The traditional AB_n monomer methods for creating HBPs face limitations due to random polymerization and the risk of gelation. By optimizing the AB_n system into an AB_x macromonomer framework, this new RAFT–HDA method enables controlled polymerization, reducing intramolecular cyclization and topological defects and broadening the range of possible polymer architectures. Additionally, more readily available and widely used novel dienes and dienophiles have been identified for the HDA reaction. The versatility of this approach was demonstrated by synthesizing a variety of HBPs with different branching degrees and molecular weights, which were thoroughly characterized by NMR, FTIR, GPC, and DLS techniques. This study provides a robust and efficient pathway for synthesizing complex polymer structures, demonstrating that the RAFT–HDA strategy enables the production of well-defined hyperbranched polymers with significant potential for applications in nanomaterials, biomedicine, and advanced functional materials.