A New Synthetic Approach to Poly- and Perfluorinated Polyethers

Linear and cyclic perfluorinated polyethers are prepared by a new route involving polymerization of a trifluorovinyl ether alcohol (CF₂=CFOR_fCH₂OH (1), R_f = CF₂CF(CF₃)OCF₂CF₂) followed by fluorination of the intermediate polyfluorinated polyethers. Polymerization occurs by ionic addition of OH groups to trifluorovinyl ether groups. In the absence of solvent, linear polymers with M_n values up to 29000 are obtained in excellent yield. In glyme solution, cyclic oligomers are the major products and a cyclic dimer is obtained in yields as high as 60%. Fluorinated macrodiols with M_n values to 5000 are obtained by copolymerization of 1 with a fluorinated diol. The intermediate linear and cyclic partially fluorinated polyethers have excellent solubility in organic solvents and the cyclics can complex anions through hydrogen bonding. Photofluorination of these polyethers with elemental fluorine in perfluorinated solvents proceeds smoothly with little fragmentation to afford the corresponding perfluorinated analogues in excellent yield.