Reversible Addition–Fragmentation Chain Transfer Synthesis and Multimodal Characterization of Poly( N -acryloylmorpholine)-Based Diblock Copolymers with Tunable Thermoresponsive Behavior and Self-Assembly Mechanisms

Thermoresponsive block copolymers exhibit sharp phase transition behavior, making them attractive platforms for smart materials and biomedical applications. In this study, diblock copolymers of poly( N -acryloylmorpholine)- b -poly( N -isopropylacrylamide) (PACMO- b -PNIPAM) and poly( N -acryloylmorpholine)- b -poly( N -vinylcaprolactam) (PACMO- b -PVCL) were synthesized via reversible addition–fragmentation chain transfer (RAFT) polymerization. Unlike conventional designs, the block sequence was strategically reversed to enable precise modulation of the critical solution temperature (LCST). The synthesized diblock copolymers show well-defined molecular architectures with controlled molar masses, confirming the successful block formation. They also demonstrate good thermal stability along with a thermal transition behavior. A concentration-dependent LCST shift into the physiological range was observed, underscoring the potential of these materials for biomedical applications. These assemblies show favorable optical responses and well-defined morphologies, indicating efficient self-organization. These results demonstrate that block sequence engineering, coupled with RAFT polymerization, provides a versatile strategy for designing advanced thermoresponsive polymers with enhanced stability, tunability, and application relevance.