This lecture series closes with the synthesis of " chimie douce " pioneered by J. Livage and J. Rouxel, former professors at the Collège. What is soft chemistry? It's based on the principle of topotactic reactions, i.e. reactions that retain the structural skeleton of the starting precursor, and therefore don't require bond breaking - which explains the low energy input required to set them in motion. Among these, the most widespread (as they are at the origin of Li+, Na+ and Mg2+ ion accumulators) are intercalation reactions. Like a millefeuilles, these involve the insertion of alkali ions between the sheets of the host structure. The fundamentals of these insertion reactions are explained, drawing on crystallographic concepts and band structures, and their realization is described using electrochemical (accumulators) and chemical (appropriate reducing or oxidizing agents) approaches, with the help of concrete, topical examples. In addition, we describe some aspects of acid-base chemistry, which also involves topochemical processes involving exchange and condensation reactions. This includes solution chemistry, which leads to the formation of polyanions or polycations, and to the elaboration of sols or gels, and also covers the natural processes involved in the formation of numerous edifices in the silicate family. We then look at grafting chemistry, which enables molecular entities to be introduced into lamellar host structures, leading to the bridging of clays (with a view to developing molecular sieves). Finally, we discuss the grafting and polymerization reactions of aniline between lamellar oxide sheets - useful for the preparation of hybrid materials for accumulators.
Although only thirty years old, this soft chemistry is already very rich and varied. There are many facets to it that I haven't been able to tackle for lack of time. These include, for example, methods for synthesizing glasses at low temperatures, or the production of ceramics at 100°C for surface coating applications. There is also a whole range of chemistry between liquid and solid (chemistry of soils, gels, colloids or fluid ferros) that I haven't covered. These different aspects will be the subject of the 2016 lecture, which will deal more specifically with physico-chemical processes for the elaboration and shaping of "tailor-made" inorganic materials for energy.
