Vinylidine fluoride

Vinylidine fluoride (CF2 = CH2) exhibits a 19F chemical shift of -82 ppm. As seen in Scheme 4.43, one alkyl substitution at the 2-position leads to about 10 ppm of shielding, with two alkyl groups providing 6-7 ppm more. The two-bond F—F coupling constant in such AB systems is typically around 50 Hz. Modest shielding of the Z-fluorine is generally observed relative to the E-fluorine of 1,1-difluoroalkenes. 

Viton. A trademark of the E.I. duPont de Nemours Co for a series of fluorelastomers based on the co-polymer of vinylidine fluoride and hexafluoropropylene with a repeating structure of [-CF2-CH2-CF2-CF(CF3H white, transparent solid sp grav 1.72—1.86. Resistant to corrosive liqs and chemicals up to 600°F, and useful in continuous service at 400—500°F. The material is resistant to weather, ozone, flame, oils, fuels, lubricants and many solvents According to Refs 2 3, Viton-A is used in many expl formulations developed by the Lawrence Livermore Laboratory, such as LX-04, LX-07, LX-10-0, LX-10-1 and LX-11-0 (see Vol... 

Plastics Polyvinyl chloride Teflon Polyethylene Polypropylene Kel-F Vinylidine fluoride Saran Epoxies ... 

Binder Nomenclature Identification a — Polyvinyl butyral resin — Monsanto Co b — Hexafluoropropylene/vinylidine fluoride 1 2 c - Polyurethane soln system - B.F. Goodrich Co d — Polytrifluorochloroethylene - 3M Co... 

Estane 5702-Fl Viton A BDNPA-F Polyurethane solution system Vinylidine fluoride/hexafluoropropylene copolymer, 60/40 wt % Bis(2,2-dinitropropyl)acetal/bis(2,2-dinitropropyl) formal, 50/50 wt % Tris- -chlorethylphosphate Chlorotrifluoroethylene/vinylidine fluoride copolymer, 3 1 Vinyl chloride/chlorotrifluoroethylene copolymer, 1.5 1 Styrene polymer, 100% Di(2-ethylhexyl)phthalate Bis(2-fluoro-2,2-dinitroethyl)foimal... 

The field of molecular electronics may be considered to encompass much more than molecular electronic devices. In its broadest context, molecular electronics may be regarded as simply the application of molecules, primarily organic molecules, to electronics. This definition would include such areas as liquid crystalline materials, piezoelectric materials such as poly(vinylidine fluoride), chemically sensitive field-eflFect transistors (CHEMFET), and the whole range of electroactive polymers. These applications are beyond the scope of this book and are covered in other reviews 34, 33). However, given the basic tenet of molecular electronics, namely, the ability to engineer and assemble molecular structures into a useful device, the broader definition raises the question of whether organic molecules can be specifically assembled or engineered for unique applications in electronics. 

VINYLIDINE FLUORIDE (75-38-7) Flammable gas (flash point <-85°F/ < —65°C). Violent reaction with oxidizers, barium, sodium, or potassium. Reacts with aluminum chloride. Incompatible with hydrogen chloride. May form explosive compounds with light metals and metallic azides. Capable of forming unstable peroxides may cause explosive polymerization. Undergoes thermal decomposition when exposed to flame or red-hot surfaces. May accumulate static electricity, and cause ignition of its vapors. The uninhibited monomer vapor may block vents and confined spaces by forming a solid polymer material. 

Poly(vinylidine fluoride) Poly(n-butyl acrylate)... 

The volume of commercial fluorine containing polymers is not large when compared with other polymers, such as poly(vinyl chloride). Fluoropolymers, however, are required in many important applications. The main monomers are tetrafluoroethylene, trifluorochloroethylene, vinyl fluoride, vinylidine fluoride, and hexafluoropropylene. 

Vinylidine fluoride boils at -84 °C. The monomer is polymerized in aqueous systems under pressure. Details of the process, however, are kept as trade secrets. Two different molecular weight materials are available commercially, 300,000 and 600,0000. Poly(vinylidine fluoride) is crystalline and melts at 171 °C. The material exhibits fair resistance to solvents and chemicals, but is inferior to polytetrafuroethylene and to polytrifluorochloroethylene. 

Copolymers of vinylidine fluoride with hexafluoropropylene are prepared in aqueous dispersions using persulfate initiators. Hexafluoropropylene does not homopolymerize but it does copolymerize. This means that its content in the copolymer cannot exceed 50%. Preferred compositions appear to contain about 80% of vinylidine fluoride. The crosslinking reactions with diamines are not completely understood. It is believed that the reaction takes place in two steps. In the first one, a dehydrofluorination occurs ... 

Discuss the chemistry of polychlorotrifluoroethylene, poly(vinylidine fluoride), and poly(vinyl fluoride). 

Figure 3.4 Western blotting technique. (A) Size separation of proteins by SDS-PAGE. (B) Transfer of the separated proteins onto nitrocellulose (NC) or poly-vinylidine fluoride (PVDF) membrane by electro blotting. (C) Visualization of proteins of interest by specific enzyme-conjugated antibody using immuno-staining. (D) Visualization of whole-protein extract by Coomassie Blue staining (left side), and immunostaining (right side), respectively.

R.K. Layek, S. Samanta, D.P. Chatterjee, and A.K. Nandi, Physical and mechanical properties of poly(methyl methacrylate) -functionalized gra-phene/poly(vinylidine fluoride) nano composites Piezoelectric p polymorph formation. Polymer, 51 (24), 5846-5856, 2010. 

Unlike polytetrafluoroethylene, polyvinyl fluoride, poly(vinylidine fluoride), and polytrifluor-oethylene yield primarily on heating HF [457]. Among these three, poly(vinylidine fluoride) yields larger amounts of HF than do the other two polymers with an accompanying formation of double bonds. 

Poly(vinylidine fluoride) has attracted much attention because of its piezoelectric properties. It is also complicated in that a number of crystal forms exist and have been carefully studied by X-ray diifrnction. The various crystal forms arise because the chain can exist in three distinct conformations and the chain alignment can be up or down along the axis and parallel or antiparalld about the axis. The three conformations are all trans, TG" TG and T3G+T3G-. 

In a study of the thermal decomposition of the copolymer of tri-fluorochloroethylene with vinylidine fluoride, it was established [34] that... 

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