HIERARSACOL · Hierarchical Self Assembly of Colloids: Control and Manipulation from Nano-Granular

Goal: to significantly extend our ability to manipulate the Self Assembly (SA) of colloidal nanoparticles (NPs) into complex 1D/2D/3D architectures (regular clusters, (composite)strings/rods, sheets, submicron colloidal crystals/liquid crystal phases of the NPs) over multiple length scales going from nano to that of granular matter. In the nano-regime quantum size effects cause materials properties to become strongly size dependent and thus highly tunable. Moreover, the synthesis of many NPs (metals, semiconductors, magnetic materials) is advanced enough that they can be made to crystallize into regular 3D lattices with new exciting functionality caused by collective effects. By performing SA in several independent stages, materials properties can be further tailored in new ways because of both access to different length scales and different NP combinations. In order to make systematic progress we will determine inter-NP potentials using 3D imaging. Both using subdiffractive confocal microscopy and cryogenic tomographic transmission electron microscopy. We will also use external fields (optical tweezers, electric/magnetic fields, shear) both to realize the complex architectures, but also to change particle properties dynamically. E.g., in monodisperse droplets of nematic phases of luminescent rodlike NPs an electric field can dramatically affect the scattering and emission of individual droplets. The droplets can subsequently be ordered in strings, sheets or crystals. Repeating the SA again delivers supra structures on the granular scale to tune e.g. heat or reagent flows. These projects combined will not only deliver new fundamental knowledge on SA, but the results are also expected to be directly useful for realizing applications based on the new meta-materials realized such as in displays, lighting, (optical) storage, (bio)sensing, catalysis, spintronics, photonic crystals, and the opto-electronics field in general.