Refining Toroidal Assemblies from Cross-Linked Triblock Copolymer Micelles

Constructing uniform and tunable toroidal assemblies remains a significant challenge. Here, we proposed a strategy to construct toroids from the self-assembly of cross-linked ABC triblock copolymer micelles. The work demonstrated that these cross-linked micelles are effective building units for forming toroidal assemblies in a vast parameter space of A and C blocks. The toroid size is precisely determined by the asymmetry of A and C patches in the cross-linked ABC triblock copolymer micelles, which can be tailored by adjusting the relative lengths and cross-linking degrees of A and C blocks. The formation of toroids follows a step-growth manner, leading to tritoroids and tetra-toroids since the length before toroid formation mismatches the toroid perimeter. We also found that reducing the copolymer concentration and increasing the incompatibility between A and C blocks can improve the uniformity of toroids. Our work provides a promising route to prepare uniform toroidal nanostructures and bridges the gap between the stepwise assembly of polymers and that of nanoparticles.