Anisotropic Magnetic Colloids: A Strategy to Form Complex Structures Using Nonspherical Building Blocks

A study was conducted to demonstrate the synthesis and microstructure of peanut-shaped colloids with a permanent transverse magnetic dipole and describe their organization into complex 1D and 2D structures. The study demonstrated the effect that hierarchical structure and colloidal properties had on the resulting self-assembly behavior. Features that distinguished this system included the high degree of orientational alignment in each particle, a selectivity in the side-by-side interaction, and shape complementarity in the peanut-type morphology. These allowed colloids to close-pack and form kinked zigzag chains when confined to a planar geometry. The free energy of a single chain bond was approximated using a simple linear aggregation model showing qualitative evidence for reversibility in this system. Investigations also revealed that these crystallites had characteristics of molecular crystal-type phases and displayed the oblique symmetry of the plane group.