Directed Self‐Assembly of Templatable Block Copolymers by Easily Accessible Magnetic Control

Abstract Magnetic control has been a prosperous and powerful contactless approach in arraying materials into high‐order nanostructures. However, it is tremendously difficult to control organic polymers in this way on account of the weak magnetic response. The preparation of block copolymers (BCPs) with high magnetostatic energy is reported here, relying on an effective electrostatic coupling between paramagnetic ions and polymer side chains. As a result, the BCPs undergo a magnetically directed self‐assembly to form microphase‐segregated nanostructures with long‐range order. It is emphasized that such a precisely controlled alignment of the BCPs is performed upon a single commercial magnet with low‐intensity field (0.35 Tesla). This strategy is profoundly easy‐to‐handle in contrast to routine electromagnetic methods with high‐intensity field (5–10 Tesla). More significantly, the paramagnetic metal component in the BCP samples can be smartly removed, providing a template effect with a preservation of the directed self‐assembled nanofeatures for patterning follow‐up functionalized species through the original binding site.