This lecture describes strategies for synthesizing hybrid materials based on the assembly of preformed monodisperse nano-objects. These hybrid building blocks comprise an inorganic core and organic surface functions. The properties of the core (optical, electrical, magnetic, mechanical, etc.) can be combined with external organic functions to enhance solubilization, transfer to polymeric media, assembly of the hybrid edifice, targeting, and so on.
These strategies, based on increasingly precise coding, are giving rise to a "vector chemistry" that assembles a variety of edifices (nanoparticles, clusters, hybrid nanocomposites) into increasingly complex hierarchical and functional architectures, which will undoubtedly one day open the door to even more original commercial hybrid materials that are fully recyclable, self-repairing and perhaps self-replicating!
Today, most of these nano-objects remain academic curiosities. They can be clusters or nanoparticles (metal oxides, metals and alloys, chalcogenides), composite core-shell nanoparticles, nano-sheets of lamellar compounds (clays, double hydroxides, phosphates, lamellar oxides and chalcogenides). These small entities of varied compositions are very often pre- or post-hybridized by organic components attached to their surface to ensure better stability and transferability to their medium of use (aqueous or non-aqueous solvents, polymers, etc.). These nanobricks can be surface-functionalized with polymerizable ligands, organic spacers, telechelic molecules or polymers, functional dendrimers, biomolecules and more. in this lecture, we illustrate different strategies and examples using a wide range of hybrid preforms (polyoligosilsequioxanes, anionic polyoxometallates (W, Mo), cationic polyoxometallates (Sn), neutral polyoxometallates (Ti, Zr, Mn), nanometals, nanoparticles of metal oxides or fluorides), opening the way to a veritable "legochemistry" enabling "tailor-made" construction of materials or hybrid assemblies with highly interesting optical, magnetic or catalytic properties. In particular, the advantages and disadvantages of these approaches using pre-formed hybrid nanobricks are discussed. Step-by-step elaboration of the material enables better control of its structure on a semi-local scale. The prefabricated object often has a lower reactivity than molecular precursors, and the inorganic component is nanometric and relatively monodisperse in size, enabling the elaboration of better-defined structures that facilitate characterization and quality control of the final material. These small entities of varying compositions must be stable under the chemical conditions imposed by the assembly stage. A discussion of the stability of the nanometric object(cluster or nanoparticle) and the dynamics of its constituents is also developed. We emphasize the need for perfect knowledge of the chemical reactivity of precursor nano-objects, as well as their surface chemistry, so that the selected object can become a genuine Lego® piece, stable under the conditions of use, and functionally "customizable", from which more complex edifices can be built, new hybrid materials, numerous and varied.
