Conjugated polymers are materials that could be used as alternatives to inorganic semiconductors in applications such as light-emitting diodes or solar cells. The self-assembled morphology of conjugated polymers plays an important role in determining their properties. The precise preparation of polymer nanostructures with particular sizes and morphologies is, thus, an interesting target for researchers.

Lei Xu, Huaibei Normal University, Anhui, China, and colleagues have precisely prepared hierarchical micellar copolymer structures, using poly(di-n-hexylfluorene)-block-poly(3-tetraethylene glycol thiophene) diblock copolymers and polyfluorene-block-polythiophene-block-poly(phenyl isocyanide) triblock copolymers. The copolymers were prepared in a one-pot process via sequential living block copolymerization using a Ni(II) complex as a single catalyst.

The crystallization-driven self-assembly of the amphiphilic conjugated diblock copolymer led to the formation of nanofibers (pictured in red) with controlled lengths and narrow dispersity. Using these uniform nanofibers as seeds, the team then introduced triblock copolymers into the seed growth process. They obtained A-B-A triblock micelles, multiarm branched micelles, or raft micelles (simplified structures pictured above) by adjusting the exact structure and hydrophobicity of the poly(phenyl isocyanide) block and the polarity of the solvent used for self-assembly.

The copolymers exhibit white, yellow, and red emissions in different self-assembled states. Overall, the work could provide an approach for the controlled preparation of hierarchical, nanostructured micelles from of conjugated polymers.

• Precisely Prepared Hierarchical Micelles of Polyfluorene‐block‐Polythiophene‐block‐Poly(phenyl isocyanide) via Crystallization‐Driven Self‐Assembly,
  Ya-Nan Pan, Chen-Chen Ye, Si-Lin Huang, Chao Wang, Man-Yi Han, Lei Xu,
  Angew. Chem. Int. Ed. 2024.
  https://doi.org/10.1002/anie.202418131