Résumé
The wide use of fluorosilicones is the result of their combination of excellent properties: good resistance to heat, solvents, acids, alkalies, and oxidizing media. Gaskets for connectics, hydraulic fluids, and heat-carrier fluids still account for the largest number of applications. After a first generation proposed by Dow-Corning, fluorinated hybrid silicones based on well-architectured fluorooligomers built by controlled stepwise telomerization of various fluoroolefins are presented. Such cotelomers are very interesting precursors of functional or telechelic derivatives (containing hydroxy, carboxy, amine or unsaturated groups).
We also described various strategies for the synthesis of tetrafluoroalkyl silanes or fluorinated disilanes or silicones. Such a series of hybrid polymers compete with those of Dow-Corning. These fluorosilicones are prepared in three steps from original nonconjugated dienes in high yields. Their thermal characteristics depend upon the spacer between the central fluorinated group and the silicon atom, the nature of lateral groups linked to silicon atoms, and the nature of the central fluorinated group (e.g., the presence of the branched CF3 group).
In spite of their price, fluorinated silicones seem to be high-value-added materials, which should challenge both industrial and academic researchers.