A New Class of Fluorinated Polymers by a Mild, Selective, and Quantitative Fluor

Most fluorinated polymers are prepared by polymerizing fluorinated monomers. An alternative route--direct fluorination of a polymer--usually involves "chemically aggressive" reagents such as elemental fluorine. Assistant processor of chemistry Marc A. Hillmyer, graduate student Yu Ren, and chemistry professor Timothy P. Lodge of the University of Minnesota, Minneapolis, now have found a mild, selective, and quantitative route to a new class of fluorinated polymers using the reaction of difluorocarbene (:CF2) with model polydienes having well-defined molecular characteristics. A solution of the polydiene and the difluorocarbene precursor (hexafluoropropylene oxide) is heated to 185 °C for 18 hours. Thermolysis of the precursor generates :CF2, which adds to all the double bonds in the polydiene. To prevent free-radical reactions such as cross-linking, the researchers add a radical inhibitor. This allows high molecular weight polydienes to be quantitatively fluorinated while preserving their molecular weight, regiochemistry, and molecular weight distribution.

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