Block Copolymer Nanoparticles with Surface‐enriched RAFT Groups Prepared by Orthogonal RAFT ‐mediated Polymerization‐induced Self‐assembly

Comprehensive Summary Block copolymer nanoparticles prepared via reversible addition‐fragmentation chain transfer (RAFT)‐mediated polymerization‐induced self‐assembly (PISA) have attracted considerable attention because of their structural controllability, compositional diversity, and scalability. However, conventional RAFT‐PISA formulations can only generate block copolymer nanoparticles with RAFT groups buried inside, which restricts subsequent surface modification and morphological control. Herein, we synthesized a multifunctional macro‐RAFT agent bearing multiple poly( N,N ‐dimethylacrylamide) side chains enriched in RAFT reactive groups. This macro‐RAFT agent enabled orthogonal RAFT‐PISA of methacrylic monomers, affording block copolymer nanoparticles with a high surface density of RAFT groups. Notably, the surface‐exposed RAFT moieties can be reactivated for the subsequent chain extension, allowing surface‐initiated RAFT polymerization to functionalize nanoparticles and construct hierarchical vesicles with well‐defined nanostructures on the surface. This work provides insights into the intrinsic origin of the different levels of control imparted by RAFT agents and offers a new design strategy for the surface modification and further functionalization of block copolymer nanoparticles.