Polymeric fluorinated surfactants structure

Polymeric fluorinated surfactants containing ionic groups may or may not be surface active, depending on their structure [213]. 

VDF and suitable comonomers can be polymerized as a microemulsion where fluorinated oil-in-water microemulsion and fluorinated surfactant are present (37-39). The core-shell structure of these self-assembling systems and their distinctive pol5unerization features along with the range of particle size distribution have been reported (40). 

Details of the processes used to produce vinylidene fluoride-hexafluoropropylene copolymers have not been disclosed but the copolymers may be prepared by emulsion polymerization under pressure using a persulphate-bisulphite initiator system. Highly fluorinated surfactants, such as ammonium perfluorooctoate, are most commonly used in order to avoid chain transfer reactions. The preferred vinylidene fluoride content for commercial copolymers is about 70% mole. The structure of such a copolymer might be represented as follows ... 

Extremely hydrophobic monomers do not polymerize well via macroemulsion polymerization due to their very low rates of monomer transport across the aqueous phase. Obviously, these monomers can be polymerized much more effectively in a miniemulsion system. One example of this is provided by Landfester et al. [320]. In this paper,fluoroalkyl acrylates are polymerized in a miniemulsion with low levels of a protonated surfactant. When fluorinated monomers were copolymerized with standard hydrophobic and hydrophilic monomers, either core-shell structures or statistical copolymers were formed. 

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