Abstract: The self-assembly behaviors of cyclic A4B6C6 triblock copolymers in A selective solvents were studied using Monte Carlo simulation method, and compared with the self-assembly behaviors of linear A4B6C6 and A4C6B6 triblock copolymers. The simulation results show that by adjusting the hydrophobicity of the C block and the hydrophobicity difference between the B and C blocks, the cyclic A4B6C6 triblock copolymer can self-assemble into various polymer micelles with different morphologies, such as segmented worms, segmented layers, and segmented vesicles with single or multiple aqueous cavities. It is worth noting that due to the unique topological structure of cyclic block copolymers, even if the hydrophobicity difference between the B and C blocks exists, the hydrophobic cores of these micelles tend to form a segmented structure with alternating B and C. Compared to the cyclic system, the self-assembly behaviors of linear A4B6C6 and A4C6B6 triblock copolymers under the same parameter conditions is relatively simple, and most of them form spherical micelles. The arrangement of B and C blocks in the hydrophobic core of spherical micelles strongly depends on the chain structure of the linear block copolymers. The above simulation results are beneficial for understanding the mechanism of the influence of chain structure on the morphology of block copolymer micelles, and provide necessary theoretical basis for the preparation of polymer micelles with specific hydrophobic core structures.

Key words: Cyclic block copolymer; Self-assembly, Topological structure, Monte Carlo simulation