Redox‐Initiated Reversible Addition‐Fragmentation Chain Transfer (RAFT) Miniemulsion Polymerization of Styrene using PPEGMA‐Based Macro‐RAFT Agent

Redox‐initiated reversible addition‐fragmentation chain transfer (RAFT) miniemulsion polymerizations are successfully conducted with an employment of trithiocarbonate‐based macro‐RAFT agents and surfactant. Two macro‐RAFT agents—hydrophilic poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA27) and amphiphilic poly(poly(ethylene glycol) methyl ether methacrylate)‐b‐polystyrene (PPEGMA27‐b‐PS33)— are examined for the miniemulsion polymerization of styrene. The use of PPEGMA27 (in the presence of sodium dodecyl sulfate (SDS)) results in a slow polymerization rate with a broad particle size. In the absence of SDS, the use of PPEGMA27‐b‐PS33 results in a broad particle size distribution due to its inability to form uniform initial droplets whereas the same amphiphilic block copolymer in the presence of SDS yields resulting products with a uniform particle size distribution. The latter exhibits a fashion of controlled polymerization with a high consumption of monomer (98% in 100 min) and a narrow molecular weight distribution throughout the polymerization. This is attributed to the formation of uniform droplets facilitated by SDS in a miniemulsion. The amphiphilic macro‐RAFT agent is able to anchor efficiently on the monomer droplet or particle/water interface and form stabilized particles of well‐defined PPEGMA27‐b‐PS block copolymer, confirmed using dynamic light scattering and transmission electron micrographs. An amphiphilic block copolymer of poly(poly(ethylene glycol) methyl ether methacrylate)‐b‐polystyrene is employed to the miniemulsion reversible addition‐fragmentation chain transfer polymerization of styrene. The chain extension polymerization reaches 99% monomer consumption and provides uniformed polymeric particles (diameter of 25–40 nm), confirmed by dynamic light scattering and transmission electron microscopy.