Synthesis of telechelic and dendritic graft polymers

Living anionic polymerization techniques were applied to the synthesis of telechelic polymers and arborescent graft polymers with well-defined architectures. The synthesis of o- and alpha,o-telechelics with sulfonate end-groups, by sulfoalkylation of homopolymers and block copolymers of n-butyl methacrylate and t-butyl methacrylate with 1,3-propane sultone, is described in the first part of the thesis. Direct reaction of poly(n-butyl methacrylate) anions with the sultone results in low functionalization levels. The yield of the reaction is greatly improved by end-capping the poly(n-butyl methacrylate) anions with a few t-butyl methacrylate units prior to sulfoalkylation. In the second part of the thesis, a new technique for the preparation of arborescent graft polymers is presented. This improved method uses acetyl chloride (rather than carcinogenic chloromethyl methyl ether) for the introduction of coupling sites on polystyrene. Arborescent polystyrene substrates are derived from successive cycles of acetylation and grafting reactions of 2-vinylpyridine-capped polystyryl anions in a generation-based scheme. Arborescent copolymers are obtained by coupling macroanions derived from isoprene or 2-vinylpyridine with acetylated polystyrene substrates of different architectures. The synthetic approach developed yields well-defined arborescent polymers with a very compact structure, characterized by a degree of branching and a molecular weight increasing geometrically for successive generations. Different materials with tailor-designed dendritic architectures and a wide range of properties should be attainable by variation of the composition and molecular weight of the side chains, and the branching density used in the procedure.