Applications of Functional Fluoropolymers

In this chaper, the two principal methods for their synthesis and some of the main applications of functional fluoropolymers will be reviewed. However, as there are many patents and papers as well as several reviews on these subjects, the review will be brief and the primary focus will be on selected applications and specific properties of functional fluoropolymers that can be achieved in highly ordered Langmuir-Blodgett (LB) films of these polymers. 

Some fluoropolymers prepared by DT with iodo-compounds have already been commercialized such as Daiel, Viton, and Technoflon. Such fluoroelastomers may find applications in high technology such as in O-rings, gaskets, hoses, transportation, medical devices, and electronics. The control of the architecture and functionality of the polymer chains makes possible the preparation of peroxide curable fiuoroelastomer with improved properties as well as the development of advanced fluorinated thermoplastic elastomers. Another application of functional fluoropolymers prepared by DT with iodo-compounds is the preparation of membranes for fuel cells. 

As was noted above, functional fluoropolymers produced by copolymerization of fluoroolefins with functional PFAVE have several unique properties, with the main disadvantage of these materials being the extremely high cost of functional monomers and the resulting high cost of the functional polymers produced from them. The fact that they are so expensive limits their wider industrial application in other fields such as catalysis and membrane separation, except for chlorine-alkali electrolysis and fuel cells, where the only suitable materials are fully fluorinated polymers because of the extreme conditions associated with those processes. 

Another examplet 1 related to a coolant conduit consisting of multiple polymer layers that render the composite structure resistant to hydrolysis and pressure with high burst strength. Motor vehicle engines are an application for a tubular form of this conduit (Fig. 10.49). In a two-layer construction, the inner layer was comprised of a fluoropolymer such as ETFE, FEP, or PVDF that has been functionalized for compatibility with the polyamide outer layer. Such a tube was formed by blow molding. 

Methods of preparation of various functional fluoropolymers suitable for fuel cell applications have been discussed by Ameduri and coworkers [ 120]. They claimed that in spite of the high cost of Nafion and its permeability to methanol, it still remains the fluorinated polymer of choice for the preparation of the proton exchange membranes for PCs. 

The great value of the unique characteristics of fluorinated polymers in the development of modern industries has ensured an increasing technological interest since the discovery of the first fluoropolymer, poly(chlorotrifluoro-ethylene) in 1934. Hence, their fields of applications are numerous paints and coatings [10] (for metals [11], wood and leather [12], stone and optical fibers [13, 14]), textile finishings [15], novel elastomers [5, 6, 8], high performance resins, membranes [16, 17], functional materials (for photoresists and optical fibers), biomaterials [18], and thermostable polymers for aerospace. 

Fluoropolymers, such as poly(tetrafluoroethylene) (PTFE), and SAM-forming molecules, such as perfluorinated thiols, silanes, and n-alkanoic acids, are widely used for surface fluorina-tion in academia and industry (e.g., as easy-to-clean surfaces). The modification of surfaces with PTFE is chemically challenging because of its low reactivity and solubility. Thiols, on the other hand, generally form stable layers on (noble) metals only and are thus not applicable to the functionalization of most materials. Utilizing catechol derivatives to fluorinate a wide variety of surfaces in order to render them hydrophobic or nonadhesive is therefore a promising alternative. 

The selection of polymer families treated here is somewhat arbitrary. For instance, fluoropolymers are more functional materials than engineering materials, and acrylic resins suffer enough thermal instability to be considered by some authors as outside the border of engineering plastics. However, FIFE (together with some copolymers) and PMMA have been considered because of their notoriety and some specific engineering applications. 

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