Site-Specific Polymerization-Induced Electrostatic Self-Assembly: Synthesis of Highly Charged Salt-Tolerant Polyion Complex Nanoreactors

We herein report a site-specific polymerization-induced electrostatic self-assembly (PIESA) that enables the precision synthesis of highly charged salt-tolerant nanoreactors. Site-specific PIESA is achieved using an anionic aromatic–aliphatic sulfonate block copolymer in photoinitiated reversible addition-fragmentation chain transfter (photo-RAFT) polymerization of a cationic monomer in water at 25 °C. Preferential complexation of cationic growing chains to the aromatic sulfonate block results in not only site-specific molecular recognition but also unique salt-tolerant PIC nanoparticles. Neutral block incorporation leads to ultrafast reaction of very dilute monomer (2.0% w/w) and exclusive formation of more salt-tolerant smaller spheres or 4 nm fibril-structured 10 nm ultrathin lamellae. The ultrathin lamellae can induce a sequence-controllable ultrafast copolymerization of oppositely-charged dilute monomers with perfect shape/size preservation up to 100% conversions, and thus can be viewed as a nanoreactor. This work opened up an avenue for the precision synthesis of highly charged salt-tolerant PIC functional nanoparticles, providing a versatile platform for easy access to structural and functional complexity from simple mixtures.