Hierarchical Vesicles with Well-Defined Nanostructures on the Surface Prepared via Orthogonal Surface-Initiated Polymerization-Induced Self-Assembly

Block copolymer vesicles prepared by reversible addition–fragmentation chain transfer (RAFT)-mediated polymerization-induced self-assembly (PISA) offer promising potential for a wide range of applications due to their hollow structure, diverse copolymer composition, and embedded reactive RAFT groups for further modification. However, it remains challenging to construct hierarchical vesicles with well-defined nanostructures on the surface via the traditional RAFT-PISA technique. In this study, we first synthesized block copolymer vesicles with RAFT groups on the surface via orthogonal RAFT-PISA of hydroxypropyl methacrylate (HPMA) in water using a series of polymethacrylate-based macromolecular RAFT (macro-RAFT) agents that contain two different RAFT moieties. In situ coassembly between the vesicles and micelles was subsequently performed via aqueous surface-initiated photo-PISA of diacetone acrylamide in the presence of an additional polyacrylamide-based macro-RAFT agent, thereby enabling the preparation of hierarchical vesicles with well-defined nanoscale domains on the surface. Moreover, the surface-initiated photo-PISA approach is also versatile to other monomers under either RAFT emulsion polymerization or RAFT dispersion polymerization conditions. These proof-of-concept experiments demonstrate that the combination of orthogonal RAFT-PISA and surface-initiated photo-PISA is a scalable and promising strategy for surface engineering of block copolymer vesicles that should find potential applications in some specific areas.