Metallopolymer-Based Shape Anisotropic Nanoparticles.

The formation of nanostructured shape anisotropic nanoparticles from poly(ferrocenylsilane)--poly(2-vinylpyridine) (PFS--P2VP) block copolymers is presented. Ellipsoidal particles with an axially stacked lamellar structure and nanosheets with a hexagonal structure of PFS cylinders are obtained under neutral wetting conditions through the use of a mixed surfactant system during self-assembly. In contrast to traditional systems, the resulting particle structure is strongly influenced by crystallization of the PFS domains under colloidal confinement with lamella-forming PFS--P2VP block copolymers leading to cylindrical morphologies. A blending approach was developed to control this morphological change and by the addition of PFS homopolymers, ellipsoidal particles with a lamellar structure could also be obtained. Ultimately, the spatial control over two orthogonal functionalities was exploited to demonstrate morphology transitions for nanosheets upon the exposure to methanol as solvent for P2VP and FeCl as a redox stimulus, opening up a variety of applications in the field of stimuli-responsive materials.