Lateral Growth\nof Hexagonal Platelet Micelles via\nCrystallization by Particle Attachment

Two-dimensional (2D) platelets with highly symmetric\nstructure\nand low dispersity in size have attracted great attention due to their\nunique planar structure with high specific surface area. The living\ncrystallization-driven self-assembly of block copolymers (BCPs) in\nselective solvent through seeded growth approach enables the formation\nof well-defined 2D platelets with excellent uniformity, which is generally\nconsidered via the epitaxial crystallization mechanism. Herein, we\ndemonstrate the lateral growth of hexagonal platelets using BCPs containing\ncrystalline side chains via an alternative growth mechanism known\nas crystallization by particle attachment. By adding hot polymer solution\nto the preformed 2D platelet seeds, spherical micelles are immediately\nformed due to the phase transition of crystalline side chain BCP.\nThese kinetically trapped spheres served as building motifs and were\nfused into the platelet edges during the aging process. The lateral\ngrowth of hexagonal platelets via crystallization by particle attachment\nwas confirmed by morphological imaging and shows living character.\nHence, the area of a hexagonal platelet could be finely manipulated\nby adding different masses of polymer solution to the 2D platelet\nseeds. Moreover, we reveal that the core length and crystallographic <i>d</i> spacing of the side chain length are both strictly required\nfor the successful lateral growth of platelets via crystallization\nby particle attachment.