Towards Colloidal Molecules and Functional Materials – Towards colloïd

The main ambition of the proposed project is to produce 'colloidal molecules' made of robust aggregates of spherical particles of different chemical nature. Each constitutive particle type would identify itself with a specific atom type. It consists of new and versatile colloids with controlled and monodisperse shapes and chemical functionalities. The use of colloidal molecules to mimic classical molecules presents the main advantage that the potential of interaction between these colloidal objects can be tuned through physico-chemical parameters of the dispersion liquid (concentration, pH, ionic strength, etc.). This opens the possibility of a thermodynamic tuning of the colloidal molecules assemblies. The study of their properties in aqueous dispersions and after stacking in the form of photonic crystals is also proposed. The synthetic route we propose to develop is based on a seeded-emulsion polymerization process where a controlled number of polymer latex particle is able to nucleate and grow onto the surface of a submicrometric silica seed particle. So, biphasic colloids would be obtained in large amounts (at the gram scale) and they may be compared to molecules made of two atom types in different arrangements: linear, angular, trigonal, tetrahedral, etc. Cryo-Transmission Electron Micrography combined with tomography analysis will provide original data concerning the actual shape of the colloids in water. The main technological barriers that we propose to break down are the following ones: 1) how to produce colloidal molecules whose each type of spherical components would mimic each type of atoms, in particular for mimicking molecules made of more than two types of atoms ? 2) how to produce highly monodisperse aqueous dispersions of such colloids ? 3) how to modify the surface of each components for controlling the interactions between colloids ? 4) how to let them self-assemble in original functional materials, such as full band gap colloidal crystals ? 5) how to control their interactions in order to form 'polymer of colloidal molecules' ? Initially based on the joint competences of ICMCB, CRPP and C2P2 partners, this ambitious project will not be viable without the contribution of the LIONS partner. Its competences will be mandatory for evaluating the monodispersity of our colloids by the X-rays and neutrons Small Angle Scattering techniques, for studying the interactions between them thanks to Ultra Small Angle Scattering techniques and therefore for identifying the key-parameters allowing to control thermodynamically their assembling into materials.