Poly fluorine role

Dynamic SIMS has also demonstrated the clustering of oxidized poly(pyr-role) into small granules (50-300 nm) embedded in a matrix of ferric stearate LB films after exposure to pyrrole vapors [221 ], and the surface enrichment of fluorinated chains in a poly(methyl methacrylate) matrix [222]. 

Fluorinated carbocations play an important role as intermediates in electrophilic reactions of fluoroolefins and other unsaturated compounds. For example, F-allyl cation 1 was proposed as a reactive intermediate in reactions of HFP with fluoroolefins catalyzed by Lewis acids [7]. The difference in stability of the corresponding allylic cations was suggested as the explanation for regio-specific electrophilic conjugated addition to CF2=CC1CF=CF2 [11]. Allylic polyfluorinated carbocations were proposed as intermediates in the reactions of terminal allenes with HF [53] and BF3 [54], ring-opening reactions of cyclopropanes [55], Carbocations are also an important part of the classic mechanism of electrophilic addition to olefins (see Eq. 2). This section deals with the questions of existence and stability of poly- and perfluorinated carbocations. 

The foremost elastomers for maximum high temperature resistance are the fluorocarbon rubbers. They play the same role in the rubber field as poly-tetrafluoroethylene ("Teflon") does in plastics. Furthermore, the inert fluorine atoms also impart a high solvent resistance as well. Hence it is not surprising that these elastomers are in a "class by themselves" (also as regards costl )... 

In this first influence, fluorine as a component of various alkoxide, aryloxide, or amino nucleophiles accelerates the chlorine replacement reactions on which the syntheses of most poly(organophosphazenes) depend. This role is attributed to the strong electron-withdrawal associated with carbon-fluorine bonds, an effect that favors dissociation of, for example, the sodium-oxygen bond in sodium alkoxides or aryloxides and... 

---