Perfluoro polymers

A very similar idea is the use of ion exchanging polymers into which redox active ions can be incorporated by equilibration with an adherent solution. Sulfonated perfluoro polymers (Nafion), polyvinylsulfonic acid , and polystyrene... 

A second surface modification has been reported by Yamamoto et al. These workers added stearic acid to their carbon paste mixture. This produced an electrode which was relatively insensitive to ascorbic acid and DOPAC relative to dopamine. It is theorized that this electrode works because of electrostatic repulsion of the anionic ascorbate and DOPAC by surface stearate groups. Ionic repulsion has also been employed by covering the surface of the working electrode with an anionic polymer membrane. Gerhardt et al. used Nafion, a hydrophobic sulfonated perfluoro-polymer, to make a dopamine selective electrode. This electrode exhibited selectivity coefficients as large as 250 1 for dopamine and norepinephrine over ascorbic acid, uric acid, and DOPAC. 

Positive photoresist amplifier perfluoro polymers, (IV), (V), (VI), and (VII), prepared by Kanna [4], Hohle [5], DiPietro, [6], and AUen, [7], respectively, were effective with an exposed light source of 160 nm and thus usable with an F2 excimer laser beam. ... 

These model studies show that we cannot distinguish at this level if there is a preferential twist in poly(difluoropolyacetylene). However, we can definitively conclude that it will not be planar. The reported crystal structure of C6H5(CF)8C6H5 (37) confirms this expectation. The molecule sits on a center of symmetry and the torsion about the central C(F)-C(F) bond is 180°C. The other two C(F)-C(F) torsions are 47° and are twisted in opposite directions. Thus if the perfluoro polymer can be synthesized, its... 

Figure 3.118 shows the effect of y radiation on the break elongation of PVF, PVDF, ETFE, FEP, and PFA. It can be seen that the impact on PVF, PVDF, and ETFE is smaller than the radiation impact on FEP and PFA FEP fares better than PFA. Figure 3.119 provides a comparison of the radiation resistance of several fluoroplastics as a function of radiation dose, as expressed by the retained elongation as percent of initial break elongation of the pol5mier. FEP is the most radiation resistant of the perfluoro-polymers while PTFE is the most susceptible. ETFE has far superior radiation resistance to all the perfluoroplastics shown in Fig. 3.119. 

The physical properties of these perfluoro polymers are summarized in Table 16.2. These perfluoropolymers are completely amorphous and contain no hydrogen atoms, show excellent chemical and thermal stability, and are soluble in fluorinated solvents such as hexafluorobenzene (HFB) and perfluorohexane. The dielectric constants of these fluoropolymers are considerably low, and they are almost unaffected by humidity. 

Kashiwagi K, Okano K, Miyajima T, Sera Y, Tanabe N, Morizawa Y, Suzuki Y (2011) Nanocluster-enhanced high-performance perfluoro-polymer electrets for energy harvesting. J Micromech Microeng 21 125016... 

The exterior of foamed wire insulation can be coated with a solid layer (jacket) of ETFE or ECTFE for wires used in telecommunications and fiber optics. This arrangement allows the foamed perfluoro-polymer to provide good electrical properties while the skin layer supplies sufficient mechanical properties. A foamed FEP wire insulation (eore), with a thickness of 0.5 mm, was coatedl with 51 pm of an ETFE jacket it had a dielectric constant of 1.64 and dielectric breakdown strength of 26.6 kV/mm. 

Wankhede, R.G., Morey, S., Khanna, A.S., and Birbilis, N. (2013) Development of water-repellent organic-inorganic hybrid sol-gel coatings on aluminum using short chain perfluoro polymer emulsion. Appl Surf Sci, 283 (15), 1051-1059. 

MTR CO2, olefins Perfluoro polymers silicon rubber, polyimide Spiral wound... 

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