Polymerization vinylidene fluoride copolymers

Teblina et al. [26] studied the kinetics of radical polymerization of metha-crylic acid in the presence of a hexafluoropropene-vinylidene fluoride copolymer. The polymerization rate increased with conversion. A grafted copolymer was formed by a reaction analogous to eqn. (40) (with F instead of... 

Unique applications employ both types of spectroscopies for structural analysis. The complementary nature of infrared and Raman effects can be seen in the structure determination of 1 1 hexafluoroisobutylene and vinylidene fluoride copolymer. This problem is virtually impossible to solve with other techniques. The two monomers can be linked in two ways during polymerization, by formation of head-to-tail (normal linking) or head-to-head linkages. By comparing infrared and Raman spectroscopic data, it was concluded that the polymers formed are indeed alternating in nature (66). It was additionally concluded that only head-to-tail linkages were observed. The proposed chemical structure is shown below. 

Most ultrafiltration membranes are porous, asymmetric, polymeric structures produced by phase inversion, i.e., the gelation or precipitation of a species from a soluble phase. See also Membrane Separations Technology. Membrane structure is a function of the materials used (polymer composition, molecular weight distribution, solvent system, etc) and the mode of preparation (solution viscosity, evaporation time, humidity, etc.). Commonly used polymers include cellulose acetates, polyamides, polysulfoncs, dyncls (vinyl chlondc-acrylonitrile copolymers) and puly(vinylidene fluoride). 

The most common methods of producing homopolymers and copolymers of vinylidene fluoride are emulsion and suspension polymerizations, although other methods are also used.55... 

The inclusion of the relatively large chlorine into the polymeric chain reduces the tendency to crystallize. Commercially available grades include a homopolymer, which is mainly used for special applications, and copolymers with small amounts (less than 5%) of vinylidene fluoride.84 The products are supplied as powder, pellets, pellets containing 15% glass liber, and dispersions. Low-molecular-weight polymer is available as oil or grease. The oil is used to plasticize PCTFE.85... 

There are essentially two methods used for the production of commercial FTPEs. The first is referred to as iodine transfer polymerization, which is similar to the living anionic polymerization used to make block copolymers such as styrene-butadiene-styrene (e.g., Kraton ). The difference is that this living polymerization is based on a free radical mechanism. The products consist of soft segments based on copolymers of vinylidene fluoride (VDF) with hexafluoropropylene (HFP) and... 

Fig. 11.6 SEM images of submicron poly(vinylidene fluoride) (PVF,) particles on a polished silicon substrate (silicon wafer, left) and a polyester copolymer (right). The (van-der-Waals) attraction force between the particles and the substrates is so great that particles embed into the soft polymeric material (right) but not into the silicon (left), although in the latter case they are flattened at the contact points [B.39, Vol. 2, p. 51]...

Fluoroelastomers can be polymerized with copolymers and terpolymers of tetrafluoroethylene, hexafluoroethylene, and vinylidene fluoride. The fluorine content largely determines chemical resistance and Tg, which increases with increasing fluorine content. Low-temperature flexibility decreases with increasing fluorine content. The fluorine content is typically 57% wt. ... 

M. Zhang, TP. Russell, Graft copolymers from poly (vinylidene fluoride-co-chlorotriflu-oroethylene) via atom transfer radical polymerization, Macromolecules 39 (10) (2006) 3531-3539. 

Polyrn rS. Polymeric monolayers are formed either by spreading preformed polymers or by polymerizing reactive monomers on the water surface. A large variety of preformed polymers has been studied, including polyacrylates and polymethacrylates, poly(vinyl butyral), poly(vinyl methyl ether), poly(vinyl acetate), poly(vinyl fiuoride), poly(vinylidene fluoride), (12), silicone copolymers, maleic anhydride copolymers, and polypeptides (1). Monomers that have been successfully polymerized at the air-water interface include derivatives of aniline (13), vinyl alcohol (14), and styrene (15). In addition to the interesting chemistry and the two-dimensional structural control, polymer LB Aims are much more robust than films formed from straight-chain amphiphiles. 

In the addition to homo-PVF2, a large number of copolymers have also been synthesized which allow to optimize the mechanical properties of fluoropolymers. Most common are copolymers with vinyl fluoride, trifluoroethylene, tetrafluoroethylene, hexafiuoropropy-lene, hexafluoroisobutylene, chlorotrifluoroethylene, and pentafiuoro-propene [521,535, 559-562]. Copolymerization with nonfluorinated monomers is possible [563] in principle but has not yet found commercial use. Fluorocarbon monomers that can help to retain or enhance the desirable thermal, chemical, and mechanical properties of the vinylidene structure are more interesting comonomers. Copolymerization with hexafluoropropylene, pentafluoropropylene, and chlorotrifluoroethylene results in elastomeric copolymers [564]. The polymerization conditions are similar to those of homopoly(vinylidene fluoride) [564]. The copolymers have been well characterized by x-ray analysis [535], DSC measurements [565], and NMR spectroscopy [565,566]. 

To develop dielectric polymers with C-CN and C-F groups, the syntheses of poly(vinylidene fluoride)-h-poly(AN, MAN, VCN) (PVDF-h-PMcN) block copolymers (Scheme 20.8), using the iodine transfer polymerization (ITP) of acrylonitrile (AN), methacrylonitrile (MAN), and vinylidene cyanide (VCN), in the presence of PVDF-1, was reported. In a first step, the ITP of vinylidene fluoride (or 1,1-difluoroethylene, VDF) with C6F13I initiated by tcrt-butyl peroxypivalate (TBPPI)... 

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 ... 

The first successful aqueous polymerization of vi-nylidene fluoride was reported in 1948 [83] using a peroxide initiator in water at 50-150°C and 30 MPa. No surfactants or suspending agents were present in the polymerization recipe. PVDF has been polymerized by a number of methods including emulsion, suspension, solution, and bulk. Later, copolymers of vinylidene fluoride with ethylene and halogenated ethylene monomers were also produced [84]. In 1960, a manufacturing process was developed and PVDF was introduced to the market. 

All aspects of the fluoropolymers including monomer synthesis, polymerization, properties, applications, part fabrication techniques, safety in handling, and recycling are discussed. Homopolymers and copolymers of vinylidene fluoride, all melt processible, have been covered in Volume Two because of the close... 

Vinylidene fluoride (VDF) can be polymerized by a variety of methods such as suspension, dispersion, and solution polymerization. It can be copolymerized with a number of fluorinated and non-fluorinated comonomers. Examples of these two groups include perfluoroolefin monomers and acrylic compounds. VDF polymers and copolymers are fabricated by melt processing as well as coating techniques. 

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