Abstract
Silsesquioxanes, which are a family of organic-inorganic hybrid silicas, can organize either in carefully controlled structures or polymerized networks. In this thesis, we approach the synthesis of such versatile structures in the following: (1) from monosilylated precursors to prepare oligomeric silsesquioxanes organized at the molecular scale and (2) from bridged organosilane precursors to obtain silsesquioxane networks organized at the mesoscale.Firstly, the synthesis of well-defined functional Janus tetrasilsesquioxanes with luminescent and coordinating functions on opposite faces is described. These tailored cyclic structures will be used for the modification of metal nanoparticle surfaces, which is particularly attractive for various applications such as imaging, sensing, catalysis, etc. Similarly, styryl-functionalized cage silsesquioxanes, including T8, T10, T12 and the first isolated T18 isomer, are prepared and fully characterized. In addition, T8 silsesquioxane with fluoride encapsulated within the cage (T8-F) is also synthesized and characterized. For the first time, the Si-F interaction is investigated as well as the functionalization of the T8-F and its integration into silica networks.Secondly, organization at the mesoscale is investigated, with particular focus on the controlled formation of pores in silsesquioxane networks. Surfactant templated bimodal periodic mesoporous organosilicas are synthesized from an organosilane precursor with bridging organic units, taking advantages of preferential partitioning of silanes within the various domains of block copolymer surfactant micelles. In addition, polysilylated dendrimers bearing degradable groups are prepared and their ability to generate functionalized pores by cleavage of the inner part of the dendrimer was demonstrated.