Surface-anisotropic spherical colloids in geometric and field confinement

The development of novel approaches to assemble colloids into hierarchical structures, in which every colloidal particle is taking a predetermined position, is at the core of modern applied colloids technology. Current assembly techniques for isotropic spherical colloids often include the application of either templates such as patterned surfaces and geometrical confinement or external forces such as electric and/or magnetic fields. More recently, researchers have begun to modify the surfaces of colloids in such a way that their natural assembly process is changed giving access to new colloids-based materials and applications. In this review, the fabrication methods for these surface-modified colloids, i.e., Janus and patchy colloids, are briefly introduced followed by a review of work from the past five years dealing with the assembly of such surface-anisotropic spherical colloids under geometric and field confinement. The observed differences in the assembly of plain and modified colloids are highlighted and the review concludes in a discussion of potential applications of these colloids and the resulting materials.