A Universal Method for Creating LCST-type Thermoresponsive Simple Polymer Coacervates

Coacervates have emerged as promising systems for achieving dynamic compartmentalization. In particular, synthetic polymeric complex coacervates represent a well-established class. However, they often decompose at high ionic strength due to charge screening effects. Conversely, simple coacervates, which forms via phase separation of a single polymer species, are promising for maintaining structural stability under these conditions. Despite this advantage, the design and understanding of synthetic simple coacervates remains limited. Here, we present a universal strategy for creating thermoresponsive simple coacervates from synthetic copolymers comprising lower critical solution temperature (LCST)-type monomers and hydrophilic monomers. Unlike conventional complex coacervates, the resulting simple coacervates maintain their integrity at high salt concentrations. This approach provides a robust and tunable platform for designing synthetic simple coacervate systems. With the growing interest in coacervates for applications in artificial cells and compartmentalized reaction systems, our findings provide a foundational framework for expanding their functional utility.