Partially fluorinated polymerization

CoF is used for the replacement of hydrogen with fluorine in halocarbons (5) for fluorination of xylylalkanes, used in vapor-phase soldering fluxes (6) formation of dibutyl decalins (7) fluorination of alkynes (8) synthesis of unsaturated or partially fluorinated compounds (9—11) and conversion of aromatic compounds to perfluorocycHc compounds (see Fluorine compounds, organic). CoF rarely causes polymerization of hydrocarbons. CoF is also used for the conversion of metal oxides to higher valency metal fluorides, eg, in the assay of uranium ore (12). It is also used in the manufacture of nitrogen fluoride, NF, from ammonia (13). 

These structures are well defined by conducting the polymerization in the presence of appropriate mono- and difunctional reagents. They are of considerable interest for the preparation of segmented block copolymers.24,25 For instance, the fluorinated macrodiols 21 have already been used to prepare an interesting new series of partially fluorinated segmented polyurethanes,26 and we are investigating other novel polymers that can be prepared from these intermediates. 

This plastic is a partially fluorinated straight-chain polymer with a very high molecular weight. It is produced by free-radical polymerization mechanism in a solvent or a hybrid (a solvent/aqueous mixture) media, using an organic peroxide initiator. Copolymerization of tetrafluoroethylene and ethylene (CH2=CH2, molecular weight 28, CAS number 74-85-1) proceeds by an addition mechanism. 

PVDF is a linear partially fluorinate polymer containing 59.4 wt% fluorine and 3wt% hydrogen. The high level of intrinsic crystallinity, typically near 60%, provides stiffness, toughness, and creep resistant properties. Incorporation of various fluorinated comonomers at low levels, typically about 5-20 wt%, enhances flexibility and clarity of PVDF by reducing the crystallinity, which in turn reduces the end use temperature rating. PVDF is commercially produced via free radical polymerization either with emulsion or suspension processes. 

Surfactants used in the polymerization are water-soluble, halogenated surfactants. They are in particular fluorinated surfactant such as ammonium, substituted ammonium, quarternary ammonium, or alkali metal salts of perfluorinated or partially fluorinated alkyl carboxylates, monoalkyl phosphate esters, alkyl ether or polyether carboxylates, alkyl sulfonates, and alkyl sulfates. 

In this chapter, we focus on the effect of fluorine as a substituent in a simple polymeric system, polyacetylene. Polyacetylene, of course, has several potentially practical uses because of its conducting and optoelectronic properties (15) and we are interested in studying how F substitution might influence these properties. Our model systems are butadiene and hexatriene, and we discuss both partially fluorinated and perfluorinated materials. Because we discovered that CF - HC hydrogen bonding is important in these systems, we also present results on the nature of the intramolecular hydrogen bond between the CF and OH groups in alcohols and enols. Related results on intramolecular coordination of alkali metals to C-F bonds in fluoroenolates are briefly described. 

Morita M, Kubo M, Matsumoto M. Interfacial properties and emulsification in systems of perfluoropolyether/nonfluorinated oil/partially fluorinated oligomeric and polymeric compounds. Colloids Surfaces A Physicochem Eng Aspects 1996 109 183-194. 

The present investigation describes the successful modification of the surface properties of polymeric solids by the adsorption of appropriate partially fluorinated compounds at polymer-air interfaces during the formation of the polymer surfaces. The extent of additive adsorption was foxmd to be dependent upon the molecular structure, fluorine content, and solubility of the additives in the solute—i.e., their organophilic-organophobic balance with respect to the solute. Certain effective additives were able to decrease the critical surface tension, of such polymers as poly(methyl methacrylate) and polyacrylamide to 20 and 11 dynes per cm., respectively. These low values correspond to surfaces containing closely packed CF2 and CF3 groups. 

Many useful polymers are not themselves the initial products of polymerization but are prepared by chemically modifying the original polymer. Partially fluorinated polyethylene used for protective gloves and to coat automobile gasoline tanks is made by exposing polyethylene to F2 diluted with nitrogen. 

The nonaqueous media used for VDF polymerization is either fluorocarbons or carbon dioxide under high pressure conditions. Fluorocarbons (54,55) and partially fluorinated hydrocarbons with no significant chain-transfer activities (56) are reported to be a suitable media for VDF polymerization. 

While partially fluorinated alkenes such as vinyl fluoride and vinylidene fluoride polymerize with the same facility as tetrafluoroethylene, the latter is unique in the class of the perfluoroalkenes with the respect to the ease of polymerization as will be described later. Perfluoroalkenes such as hexafluoropropylene (HFP) and hexafluorobutadiene polymerize only with great difficulty as the result of the steric inhibition in the propagation step [598]. HFP can be converted to high-molar-mass polymer only at pressures above 1000 atm. The polymerizations are carried out most conveniently in a perfluorinated solvent using perfluorinated free-radical initiators [599]. For the polymerization of hexafluorobutadiene, similar conditions are reported [600]. Due to these very drastic polymerization conditions, these oligomers/polymers are not yet commercially applied. 

Sanders DP, Connor EE, Gmbbs RH, Hung RJ et al. (2003) Metal-catalyzed addition polymers for 157 nm resist applications. Synthesis and polymerization of partially fluorinated, ester-fimctionalized tricyclo[4.2.1.02,5]non-7-enes. Macromolecules 36 1534-1542... 

The present chapter covers information published by resin manufacturers about the commercially available grades of melt processible fluoropolymers. The first two polymers are perfiuorinated resins, followed by partially fluorinated polymers ethylene-tetrafiuoro-ethylene and ethylene chlorotrifiuoroethylene, andpoly-vinylidene fluoride and polyvinylfiuoride, and finally concluding with fluoroplastics polymerized in supercritical carbon dioxide. Commercially available resins have been classified by type, grade, and manufacturer. Properties of commercial grades have been presented in this chapter based on the literature published by the manufacturers. 

Perfluoropolymers bum, but do not continue to bum when the flame is removed. All perfluorinated fluoropolymers pass a UL 83 vertical flame test and are classified 94 V-0 according to Underwriters Laboratory (UL) in their burning test classification for polymeric materials. Limiting oxygen index (LOI) by ASTM D2863 is 95% or higher for PTFE, PFA, FEP, and PCTFE. Partially fluorinated fluoropolymers are more flame resistant than other thermoplastics but not quite as resistant as the perfluorinated fluoropolymers, as evidenced by their lower EOI values. PVDF, ETFE, and ECTFE meet UE 94 V-0. Table 13.48 lists the EOI of various fluoropolymers. 

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