(623i) Magnetic Field Driven Assembly of Multicomponent Low-Symmetry Supraparticles

Supraparticles are a class of high-order colloidal structures that are assembled by introducing a net attractive interaction between particle-pairs in bulk fluid. The assembled state and spatial orientation of the supraparticles is governed by the physical design of the colloidal building block and corresponding asymmetry in the interparticle interactions. We use this combination of asymmetry in the particle design and interactions to direct the assembly of mixtures of patchy and non-patchy colloidal particles into clusters of unusual local symmetry and spatial distribution. We use external magnetic field as a tool to program the assembly of Janus and non-Janus microspheres into A1Bn type-structures where the B particles are localized on the magnetic hemisphere A. We show that relative change in magnetic polarizability of the particles and bulk fluid enables programming the local symmetry of the assembled supraparticles. We demonstrate that the assemblies obtained can undergo rapid disassembly upon removal of the external magnetic field, a crucial property for responsive materials applicable in actuators, sensors as well as magneto-rheological fluids.