Epoxy-functional sterically stabilized diblock copolymer nanoparticles via RAFT aqueous emulsion polymerization: comparison of two synthetic strategies

Polymerization-induced self-assembly (PISA) is a powerful and versatile technique for the synthesis of a wide range of sterically stabilized diblock copolymer nano-objects. Recently, PISA has been used to prepare epoxy-functional diblock copolymer worms and spheres directly in aqueous solution by incorporating glycidyl methacrylate (GlyMA) into the core-forming hydrophobic block. Herein, the synthesis of diblock copolymer spheres via reversible addition-fragmentation chain transfer (RAFT) aqueous emulsion polymerization of benzyl methacrylate is examined, in which the epoxy groups are exclusively located within a non-ionic poly(glycerol monomethacrylate)-based stabilizer block. Two synthetic strategies are explored: i) using an epoxy-functional RAFT chain transfer agent (CTA) to place an epoxy group at the terminus of every stabilizer block and ii) incorporation of ≈1 epoxy group per stabilizer chain via copolymerization of GlyMA with glycerol monomethacrylate (GMA). The epoxy groups conferred by the GlyMA comonomer are significantly more resistant to hydrolysis than those introduced using the epoxy-functional RAFT CTA. The epoxy-functional nanoparticles are subsequently reacted with various water-soluble thiols to modify their electrophoretic behavior. Such nanoparticles are expected to offer potential applications in the context of mucoadhesion.