Partially fluorinated properties

In 1954 the surface fluorination of polyethylene sheets by using a soHd CO2 cooled heat sink was patented (44). Later patents covered the fluorination of PVC (45) and polyethylene bottles (46). Studies of surface fluorination of polymer films have been reported (47). The fluorination of polyethylene powder was described (48) as a fiery intense reaction, which was finally controlled by dilution with an inert gas at reduced pressures. Direct fluorination of polymers was achieved in 1970 (8,49). More recently, surface fluorinations of poly(vinyl fluoride), polycarbonates, polystyrene, and poly(methyl methacrylate), and the surface fluorination of containers have been described (50,51). Partially fluorinated poly(ethylene terephthalate) and polyamides such as nylon have excellent soil release properties as well as high wettabiUty (52,53). The most advanced direct fluorination technology in the area of single-compound synthesis and synthesis of high performance fluids is currently practiced by 3M Co. of St. Paul, Minnesota, and by Exfluor Research Corp. of Austin, Texas. 

Partially fluorinated X-IP has been used for a number of years as an additive in the inert lubricant PFPE film on the surface of a magnetic hard disk to enhance start/stop durability of PFPE lubricants [29,30]. Recently it has been used as a vapor lubricated film on the surface of the disks [31 ]. In order to avoid the PFPE being catalyzed to decomposition by the slider material AI2O3 (refer to Section 3.4), XI -P was also examined as a protective film on the surface of the magnetic heads [25,32]. The results of CSS tests indicate that the thermal stability of the lubricant was greatly improved in the presence of X-1P, and the thickness of X-1P film on the slider surface has an important influence on HDD lubrication properties. 

As part of an effort to develop high-performance, high-temperature-resistant polymers for microelectronics applications, we also recently described a series of both partially fluorinated and nonfluorinated poly(aryl ether ketone)s containing amide, amide-imide, cyano oxadizole, or pyridazine groups and characterized their thermal and electrical properties.11... 

As the fluorination proceeds, solubilities, basicities, oxidation potentials, etc. of the successive products will alter such that new molecules formed will become competitors in the dynamic equilibrium between electrolyte and anode surface. It is supposed that this process continues until perfluorination takes place, unless, in the case of partially fluorinated compounds which are resistant to further fluorination by virtue of there structure, they remain in the HF-phase or in the perfluorinated phase depending upon the number and positions of remaining hydrogen atoms and the properties which this imparts. 

Thus, it is stated, in this model of the ECF process, the physico-chemical properties of the partially fluorinated intermediates - or more precisely, the course of these properties with progressive fluorination - provide the clue to a better understanding of the mechanisms involved. 

Table 14.5 lists the thermal, electrical, and optical properties of perfluorinated polyimides, along with those of partially fluorinated and unfluorinated polyimides. Because of die flexible structure of the lOFEDA component, the polymer decomposition temperatures and values of perfluorinated polyimides are slightly lower than those of conventional polyimides. This coincides with the results of Hougham et al. who reported that an increase in fluorine content in... 

Table 14.4. Mechanical Properties of Perfluorinated (10FEDA/4FMPD), Partially Fluorinated (6FDA/TFDB), and Unfluorinated (PMDA/ODA) Polyimide Films ...

Table 14.5. Thermal, Electrical, and Optical Properties of Perfluorinated, Partially Fluorinated, and Unfluorinated Polyimides...

These characteristics show that perfluorinated polyimides are promising materials for waveguides in integrated optics and optical interconnect technology. The thermal, mechanical, and optical properties of perfluorinated polyimides can be controlled by copolymerization in the same manner as partially fluorinated polyimides. ... 

Synthesis and Properties of Partially Fluorinated Polyimides for Optical Applications... 

This chapter describes the synthesis of partially fluorinated polyimides for optical teleconununications applications," " 2 their optical transparency (optical loss), refractive index, and birefringence properties" in addition to their fundamental properties. It also describes their device application as optical interference filters," " optical waveplates," and optical waveguides." -" ... 

Under appropriate conditions, the perfluorocarbon (CF3)3CCF2CF2-C(CF3)3is obtained in 89%yield (70b). As may be seen from the reaction scheme, a number of partially fluorinated products are also isolable and it is clear that the protons are readily accessible to fluorine. The physical properties of highly branched fluorocarbons (see Table IX) are most unusual. 

The data in Table 9 also allows one to reach conclusions regarding the elec-trophilicity vs nucleophilicity of the partially-fluorinated radicals since the three styrene substrates have a considerable range in IP values. /1-Fluorine, and to a lesser extent y-fluorine, substitution would appear to have a small impact on electrophilicity, whereas a single a-fluorine substituent seems to impart slightly nucleophilic properties. In a recent study, Takeuchi et al. have examined both computationally and experimentally radicals which bear both an a-fluorine substituent and an electron withdrawing ester function. They found that the a-fluorine substituent makes such radicals more electrophilic, but that they still add more readily to styrene than they do to acrylonitrile [127],... 

PFA and MFA exhibit considerably better electrical properties than most traditional plastics. In comparison with the partially fluorinated polymers, they are only slightly affected by temperature up to their maximum service temperature.54... 

Emphasis was first placed on the adsorptive behavior of Compound D on the surface of chromium because that metal has the following desirable properties (a) it is an excellent adsorbent for carboxylic acid groups (5) (b) a large body of data is available on the properties of adsorbed, monomolecular films of aliphatic (16), partially fluorinated (13), fully fluorinated (2), and chloro-fluoro carboxylic acids (2) (c) the metal surface can be readily and reproducibly cleaned by standard metal-lographic polishing techniques and (d) there is a hard, coherent, thin-film oxide on the surface (18). 

Partially fluorinated fluoropolymers confain hydrogen (H) or other atoms such as chlorine, in addition to fluorine and carbon. The mosf significanf are homopolymers and copolymers of vinylidene fluoride (VDF). There are also copolymers and homopolymers of CTFE, alfhough some have elastomeric properties. Other significant fluoroplastics include ETFE and PVF. 

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. 

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. 

Cyanoformamidines, exhibiting nucleophilic and electrophilic properties in the 1,3-positions, react with hexafluoroacetone forming five-membered heterocycles (86CB2127). This ability to form five-membered heterocycles is the major characteristic of hexafluoroacetone, which is also inherent in some perfluorinated and partially fluorinated ketones, aldehydes, and imines in their reactions with a-functional derivatives of carboxylic acids, as well as w-amino, a-N-alkylamino,... 

Partially fluorinated fluoropol5miers are significantly different from the perfluoropol5miers with respect to properties and processing characteristics. For example, perfluoropolymers are more thermally stable but physically less hard than partially fluorinated polymers. Both classes of fluoropolymers are discussed in Ch. 3. 

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