Morphological Diversity from the Solution Self-Assembly of Block Copolymer Blends Containing High Molecular-Weight Hydrophobic Blocks.

Self-assembled structures of high molecular-weight block copolymers (BCPs) can prematurely settle to local energy minima without reaching a time-averaged equilibrium, resulting in the emergence of intriguing morphologies, such as 3D micellar networks. This nonergodic behavior is evident in binary blends of BCPs with different molecular weights. This study reports the solution self-assembly of the blends of two branched-linear BCPs with similar block chemistries but different molecular weights of the hydrophobic blocks. A progressive transition of morphologies from hexosomes and cubosomes to 3D micellar networks, short cylinders, and spherical micelles is demonstrated, which is driven by the increase in the composition of low-molecular-weight BCP in the blend. The labeling of the micellar networks using Au nanoparticles confirms that lower molecular-weight BCP concentrates at the surface of micellar networks.