Microfibres and macroscopic films from the coordination-driven hierarchical self-assembly of cylindrical micelles

Anisotropic nanoparticles prepared from block copolymers (BCPs) are of growing importance as building blocks for the creation of synthetic hierarchical materials. However, the assembly of these structural units is generally limited to the use of amphiphilic interactions. Herein, we report a simple, reversible coordination-driven hierarchical self-assembly strategy for the preparation of micron-scale fibers and macroscopic films based on monodisperse cylindrical BCP micelles. Coordination of Pd(0) metal centres to phosphine ligands immobilised within the soluble coronas of BCP micelles was found to induce intermicelle crosslinking, affording stable linear fibers comprised of micelle subunits in a staggered arrangement. The mean length of the fibers could be varied by altering the micelle concentration, reaction stoichiometry, or aspect ratio of the micelle building blocks. Furthermore, the fibers aggregate upon drying to form robust, self-supporting macroscopic micelle-based thin films with useful mechanical properties that are analogous to crosslinked polymer networks, but on a longer length scale.