Self-assembly of luminescent triblock bottlebrush copolymers in solution

Abstract

Self-assembly presents elegant and effective bottom-up strategies for the construction of complex polymeric materials. However, the hierarchical self-assembly behaviour of triblock bottlebrush copolymers remains virtually unexplored. Here we describe the synthesis of amphiphilic BBCPs composed of an n-butyl acrylate block, a p-bromostyrene block, and a carbazole-based benzyl acrylate organic semiconductor block, and their self-assembly to give micelle structures in selective solvents. Five BBCPs with different block orders and block ratios were prepared via the grafting-through method by ring-opening metathesis polymerization of pre-synthesized macromonomers. The resulting BBCPs gave various globular and hierarchical morphologies when self-assembled in selective solvents, with CMCs as low as 0.72 and 10.5 nM in ethyl acetate and 2,2,2-trifluoroethanol respectively, and with quantum yields approaching unity. Transmission electron microscopy and dynamic light scattering studies reveal that the block ratios and block orders have large effects on the resulting self-assembled morphologies observed, providing a starting point for further investigations into the hierarchical self-assembly of bottlebrush copolymers.