Coacervate core micelles: Controlling size with polymer architecture

The phenomenon of complex coacervation, where oppositely charged polymers in solution undergo liquid-liquid phase separation forming a polyelectrolyte-rich phase and a solvent-rich phase, can be harnessed to design inhomogeneous structures by controlling polymer architecture. Here we consider diblock copolymers composed of a charged block and a neutral-hydrophilic block. Under relatively dilute conditions, these polymers assemble into coacervate core micelles with a core composed of charged blocks and a highly solvated corona composed of neutral, hydrophilic blocks. As the core can encapsulate charged, hydrophilic drugs, unlike amphiphilic micelles, these micelles have been proposed as drug-delivery vehicles. For such applications, it is essential to understand the dependence of polymer architecture, specifically the charged block length, on the resulting micelle. We probe this dependency focusing on how the critical micelle concentration, core size, core density and corona size vary. We expect that understanding these dependencies will assist in the design of coacervate core micelles.