Amorphous fluoropolymer applications

Amorphous fluoropolymers have many applications in the areas of advanced materials where they are used in applications requiring thermal and chemical resistance. Their manufacture is hindered by their low solubility in many solvents. Many fluoropolymerizations cannot be carried out in hydrocarbon solvents because the radical abstraction of hydrogen atoms leads to detrimental side reactions. Chlorofluorocarbons (CFCs) were thus commonly used, but their use is now strictly controlled due to their ozone depleting and greenhouse gas properties. Supercritical carbon dioxide is a very attractive alternative to CFCs and it has been shown that amorphous fluoropolymers can be synthesized by... 

Teflon AF is truly a family of amorphous fluoropolymers with an extraordinary combination of properties. All of the excellent properties of die existing fluoropolymers have either been retained or improved upon and properties arising from the amorphous nature and the presence of microvoids in the AF family of polymers have been added. The similarities and differences of AF and other Teflon polymers are summarized in Table 2.3. This unique combination of properties of Teflon AF amorphous fluoropolymers makes them well suited for applications that had previously precluded polymeric materials,... 

Very saline samples and/or the addition of organic solvents to the samples were used in early applications in order to provide high refractive indices [88], but the applicability of the LCW flow cell was limited because, in general, only dilute aqueous samples with low refractive indices have been analysed. The development of different kinds of amorphous fluoropolymers (Teflon AFs) with refractive indices lower than that of pure water enabled the design and overall acceptance of flow cells relying on LCWs [89,90]. 

These amorphous fluoropolymers are chemically as well as thermally stable, soluble in fluorinated solvents, have low dielectric constants, and the films are transparent. They have unique properties compared to traditional fluoropolymers. The amorphous polymers have high potential in many applications. The following are representative examples that are being pursued polymer waveguides [24,25], pellicles used in the photolithographic reproduction of semiconductor integrated circuits [26], insulators and hydrophobic surfaces for electrowetting [27,28], polymer optical fibers [29,30], and membranes for gas separations [31-33], Here, we describe two examples of the use of the amorphous perfiuorinated polymers optical fibers and gas separation membranes. 

Stones are protected from deleterious effects of water and pollution by application of amorphous fluoropolymer solution." Solvent is selected from the group consisting of acetone, methyl-ethyl ketone, ethyl acetate, t-butyl acetate, hydrochlorofluorocarbons, chlorofluorocarbons, hydro fluorocarbons and perfluorocarbons." Another method uses epoxy-modified silane in hydrophilic solvent." ... 

Applications of fluoropolymers are still growing, even decades after the discovery of the first plastic (polytetrafluoroethylene) in this family. The increasing use of fluoropolymers in such dynamic industries as wire and cable insulation, automotive, aerospace, oil and gas recovery, and semiconductor manufacture has led to significant material developments and trends in the last few years. New fluoropolymers have been introduced to the market (amorphous fluoroplastics, modified PTFE, low-temperature fluoroelastomers, and amine-resistant fluo-... 

Kawai s (7) pioneering work almost thirty years ago in the area of piezoelectric polymers has led to the development of strong piezoelectric activity in polyvinylidene fluoride (PVDF) and its copolymers with trifluoroethylene and tetrafluoroethylene. These semicrystalline fluoropolymers represent the state of the art in piezoelectric polymers. Research on the morphology (2-5), piezoelectric and pyroelectric properties (6-70), and applications of polyvinylidene fluoride 11-14) are widespread in the literature. More recently Scheinbeim et al. have demonstrated piezoelectric activity in a series of semicrystalline, odd numbered nylons (75-77). When examined relative to their glass transition tenq>erature, these nylons exhibit good piezoelectric properties (dai = 17 pCTN for Nylon 7) but have not been used commercially primarily due to the serious problem of moisture uptake. In order to render them piezoelectric, semicrystalline polymers must have a noncentrosynunetric crystalline phase. In the case of PVDF and nylon, these polar crystals cannot be grown from the melt. The polymer must be mechanically oriented to induce noncentrosynunetric crystals which are subsequently polarized by an electric field. In such systems the amorphous phase supports the crystalline orientation and polarization is stable up to the Curie temperature. 

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