Uniform two-dimensional square assemblies from conjugated block copolymers driven by π-π interactions with controllable sizes

Two-dimensional (2-D) micro- and nano-architectures are attractive because of their unique properties. However, the formation of 2-D supramolecular highly symmetrical structures with considerable control is still a major challenge. Here we present a simple approach for the preparation of regular and homogeneous 2-D fluorescent square non-crystallization micelles with conjugated diblock copolymers PPV₁₂-b-P2VP _n through a process of dissolving-cooling-aging. The scale of the formed micelles can be controlled by the ratio of PPV/P2VP blocks and the concentration of the solution. The results reveal that the micelles of PPV₁₂-b-P2VP _n initially form 1-D structures and then grow into 2-D structures in solution, and the growth is driven by intermolecular π-π interactions with the PPV₁₂ blocks. The formation of 2-D square micelles is induced by herringbone arrangement of the molecules, which is closely related to the presence of the branched alkyl chains attached to conjugated PPV₁₂ cores.