Synthesis of Multicompositional Onion-like Nanoparticles via RAFT Emulsion Polymerization

Synthesis of multicompositional polymeric nanoparticles of diameters in the range 100-150 nm comprising well-defined multiblock copolymers reaching from the particle surface to the particle core has been conducted using surfactant-free aqueous macroRAFT emulsion polymerization. The imposed constraints on chain mobility as well as chemical incompatibility between the blocks result in microphase separation, leading to formation of an onion-like multilayered particle morphology with individual layer thicknesses of approximately 20 nm. The approach provides considerable versatility in particle morphology design as the composition of individual layers as well as the number of layers can be tailored as desired, offering more complex particle design compared to approaches relying on self-assembly of preformed diblock copolymers within particles. Interestingly, microphase separation can occur in these nanoparticle-based systems under conditions where the corresponding bulk system would not likely result in microphase separation as predicted by theory.