Controlled Growth of Patchy Nanosheets via Crystallization-Driven Self-Assembly of POSS-Containing Block Copolymers

2D nanomaterials with precisely controlled dimensions and spatially segregated functionalities hold tremendous promise for advanced applications, yet the high-yield fabrication of polymeric analogues with compositional complexity remains challenging. Herein, we report a strategy for the controlled growth of patchy nanosheets via crystallization-driven self-assembly (CDSA) of polyhedral oligomeric silsesquioxane (POSS)-containing block copolymers (BCPs). Two sets of BCPs, BPOSS₄-APOSS and BPOSS₂-KPOM, were precisely synthesized through efficient thiol-maleimide coupling. BPOSS₄-APOSS undergoes CDSA to form uniform, monodisperse 2D nanosheets with a thickness of ≈4.5 nm, serving as crystalline seeds. Critically, BPOSS₂-KPOM can undergo kinetically controlled heteroepitaxial deposition exclusively at the edges of preformed nanosheets, yielding patchy 2D architectures with tunable peripheral thickness. The inner region maintains the original BPOSS₄-APOSS structure with hydrophilic APOSS coronas, while the outer patch consists of BPOSS₂-KPOM featuring polyoxometalate (POM)-based coronas. This sequential epitaxial growth enables precise control over the lateral dimensions and patch thickness through multiple growth cycles. Our work demonstrates the feasibility of heteroepitaxy in precision molecular systems and establishes a versatile route toward multifunctional 2D nanomaterials with spatially encoded chemical complexity, opening new avenues for the rational design of hierarchical nanostructures.