Enaminoester-Based Unsymmetrical Hantzsch Reaction for One-Step Hetero-Difunctionalization of Polymers

Abstract

The emergence of novel and efficient polymerization methodologies grounded in organic transformations has profoundly advanced the field of polymer science and materials engineering. In this work, the efficient enaminoester-based unsymmetrical Hantzsch reaction was established as a robust postpolymerization modification approach. This transformation exhibits several attractive features, including high reaction efficiency, mild and catalyst-free conditions, water as the sole byproduct, broad functional group tolerance, and the direct generation of unsymmetrical 1,4-dihydropyridine structures. Notably, modification degrees up to >99% were achieved across a wide range of substrates, enabling the straightforward heterodifunctionalization of the polymer backbone. To demonstrate this versatile strategy, we rationally designed and synthesized a novel enaminoester-containing polymethacrylate as the polymeric scaffold. Employing a series of Knoevenagel condensation products as dual-functional modifying agents, we conducted the high-yielding postpolymerization modification under mild, catalyst-free conditions. Structural and property characterization revealed that the introduction of diverse pendent groups via the Hantzsch reaction significantly enhanced the thermal stability, glass transition temperatures, and UV-blocking performance of the polymers. Furthermore, we showcase the application of this strategy in the development of photoluminescent and mechanically tunable cross-linked polymer networks, highlighting its transformative potential in polymer science and material engineering. This robust approach, enabled by the efficiency and generality of the enaminoester-based Hantzsch reaction, provides a versatile platform for the synthesis of advanced functional polymeric materials.