Synthesis of fluorinated polymers by chemical modification

Polymers that contain atomic fluorine in or along the backbone possess many desirable physical properties. In general, fluoropolymers exhibit high thermal stability, enhanced chemical resistance, and low surface energy when compared to their non-fluorinated analogs. Two distinct routes are ordinarily utilized for the synthesis of these interesting macromolecules. Firstly, they can be prepared by the polymerization of fluorine-containing monomers (e.g. polytetrafluoroethylene from tetrafluoroethylene). Secondly, fluoropolymers can be prepared through polymer modification reactions that incorporate fluorine atoms or fluorine-containing moieties into a non-fluorinated parent polymer. Many commercially available fluoropolymers are prepared by the polymerization of fluorinated monomers. However, the different types of fluoropolymers that can be prepared by this route are limited by the availability of unique, suitably reactive fluorine-containing monomers. On the other hand, polymer fluorination methods, while less commonly practiced, allow for the preparation of novel fluorinated materials for which there is no suitable fluorine-containing monomer. Numerous methods have been described for the fluorination of polymers. These methods range from reactions that use fluorinated reagents to degrade or crosslink the polymeric substrate, to reactions that add fluorine atoms to the polymer in a highly non-specific fashion, to methods that introduce fluorine in a very selective manner to specific functional groups present in the parent polymer backbone. In the context of this review, ideal polymer fluorination methods are ones that allow for the selective and controlled introduction of fluorine atoms or fluorine-containing molecules to functional groups in or the polymer backbone without inducing degradation or crosslinking of the parent polymer chains. This article reviews methods for the bulk incorporation of fluorine in or along the backbone of macromolecules with fluorination procedures adhering 41 to these criteria. (C) 2002 Elsevier Science Ltd. All rights reserved.