Use of telechelic fluorinated diiodides to obtain well-defined fluoropolymers

Different methods of synthesis involved in the preparation of fluorinated t elechelics (or alpha,w-difunctional compounds) from alpha,w-diiodoperfluoro alkanes for obtaining well-defined fluoropolymers are described. This revie w focuses on molecules in which fluorinated chains are located on the backb one and not in a lateral position. First, a bibliographical approach develo ps the syntheses of alpha,w-diiodoperfluoroalkanes (1) either by chemical t ransformations of telechelic derivatives or by telomerisation of fluoroolef ins with molecular iodine or diiodoperfluoroalkanes. Then, fluorotelechelic s are synthesised by means of four different processes: (a) by the chemical change in the presence of metalic salts: Cb) from the bismonoaddition of 1 to w-functional unsaturated derivatives; (c) from the bis(monoethylenation ) of 1 followed by difunctionalisation (e.g., nucleophilic substitution); ( d) from the coupling reactions between 1 and alpha-iodo-w-functional reacta nts. Finally, this review describes how several well-defined fluoropolymers can be produced from these fluorinated telechelics. Their specific chemica l, physical and thermal properties are discussed with regard to modern indu strial requirements. (C) 1999 Elsevier Science S.A. All rights reserved.