Depletion-Induced Chiral Chain Formation of Magnetic Spheres.

Abstract

Simulations by Pickett et al. predict that aligned spherical particles with a dipole moment can self-assemble into helical structures in the presence of an additional attractive interaction. This prediction was experimentally tested employing superparamagnetic silica spheres and depletion polymer polyethylene oxide. A Helmholtz cube was used to produce a homogeneous magnetic field. The observed structures of the arised single and double chains were analysed by optical microscopy within a homogeneous magnetic field. The behaviour of superparamagnetic silica particles in the presence of PEO was characterized by determining chain length, amount of double chains and the rotation of the double chains. Additionally, photo-crosslinkable surface-modified superparamagnetic silica particles were used to attempt to fixate the structures because the structures will fall apart without the magnetic field.