Telechelic Polyethers by Living Polymerizations and Precise Macromolecular Engineering
Résumé
Telechelic polyethers, decorated with functional groups at one or both chain-ends, are of increasing interest over the past sixty years. Several aspects concerning their precise synthesis, the design of advanced polymeric macromolecular architectures and materials by taking advantage of the presence of the functional end-groups are discussed. Beside their synthesis, in most cases via ring-opening poymerization, the knowledge of their precise functionality is of critical importance, it is too often missing in the current literature. A general overview on the controlled synthesis, via anionic ring-opening polymerization (AROP) of ethylene oxide (EO), of -methoxy,
-hydroxy telechelic PEOs, ,-dihydroxy telechelic PEOs, and multifunctional -telechelic hydroxy star-shaped or hyperbranched PEOs has been given first. An important part of the chapter was devoted to the controlled synthesis by AROP of EO, either directly via a functional initiator or by deactivation with an appropriate low molar mass compound, of a large number of mono or bifunctional PEO or PTHF telechelics or macromonomers. Besides these two general methods, a large number of post-polymerization methods have been developed to fit quantitatively the chain-ends with a large number of different functional groups. Special emphasis was given in this chapter to heterofunctional polyether macromonomers. Moreover thesefunctional polymers are ideal precursors for the synthesis of graft copolymers, which usually exhibit unique properties in solution and in the solid state. The reactivity of the polyether end-groups has a determinant effect on their incorporation in the graft copolymer. Much efforts have also been devoted to bifunctional polyether telechelics or macromonomers well-suited for the synthesis of cross-linked materials. The synthesis, the characterization and the properties of hydrogels either by polymerization of bifunctional polyether macromonomers or by coupling -hydroxy telechelic PEOs with appropriate multifunctional pluriisocyanate would alone justify a chapter. Typically, functional polyethers represent unique building-blocks to access chain-end modified polymers fitted with long hydrophobic blocks, including fluorinated or organic-inorganic ones. The final section adressed PTHF and POM telechelics their synthesis and some applications of these polymers in the elaboration of macromolecular architectures. New polymerization processes or functionalization/coupling processes have emerged, particularly controlled radical polymerization and “click-chemistry“ to design new architectures based on polyether telechelics.