Fluorocarbon liquids properties

Surface Protection. The surface properties of fluorosihcones have been studied over a number of years. The CF group has the lowest known intermolecular force of polymer substituents. A study (6) of liquid and solid forms of fluorosihcones has included a comparison to fluorocarbon polymers. The low surface tensions for poly(3,3,3-trifluoropropyl)methylsiloxane and poly(3,3,4,4,5,5,6,6,6-nonafluorohexyl)methylsiloxane both resemble some of the lowest tensions for fluorocarbon polymers, eg, polytetrafluoroethylene. 

The physical properties of saturated fluorocarbons and their analogous hydrocarbons differ in many respects [4 5] Sahirated fluorocarbons have the lowest dielectric constants, surface tensions, and refractive indexes of any liquids at room... 

The frictional properties of PTFE are unique Its unusually low static coefficient of fnction decreases with mcreasing load and is lower than the dynamic coefficient of fnction. This precludes stick-shp behavior. The low surface energy also prevents wetting by liquids other than low-surface-tension fluids Like fluorocarbons. 

Because PTFE melts at such a high temperature and the melt is very viscous, it is difficult to work by conventional plastics techniques such as injection molding or extrusion. It is usually formed into useful shapes by sintering at about 380 °C sometimes liquid alkanes are used as a carrier, but the product then tends to be porous (this emerges as a serious problem when thin-walled objects are machined out of PTFE stock). Accordingly, several fluorocarbon thermoplastics have been developed that have lower melt viscosities, at the expense of somewhat poorer thermal and mechanical properties than PTFE. For example, the thermoplastic FEP (fluori-nated ethylene propylene), made by copolymerization of F2C=CF2 and... 

Fluorocarbon derivatives have another interesting and potentially useful property. They dissolve large quantities of oxygen. This fact, combined with their nontoxicity, has led to their use as blood replacements in heart surgery on experimental animals. Mice can live totally immersed in oxygen-saturated liquid fluorocarbons. 

Liquid fluorocarbon was used as continuous phase by Perez-Moral and Mayes [19] as well. They proposed a new method for rapid synthesis of MIP beads, in that they prepared 36 polymers imprinted for propranolol and morphine with different amounts of EDMA as a cross-linker and different functional monomers (MAA, acrylic acid, hydroxyethyl methacrylate, 4-vinylpyridine) directly in SPE cartridges. The properties of MIP microspheres prepared by this method were very similar in terms of size, morphology and extent of rebinding to microspheres prepared by conventional suspension polymerisation in perfluorocarbons as well as to bulk polymers prepared in the same solvent. The most notable advantages of this method are no waste production (no transfer of beads during washing steps) and possible direct use for a variety of screening, evaluation and optimisation experiments. 

The introduction of perfluorinated groups generally favors microphase separation due to the immiscibility of fluorocarbons with hydrocarbons [66]. Norbornene derivatives with perfluorinated endgroups in the side chain were prepared by Wewerka et al. [67]. Monomer XII contained a relatively long (CF2)8-chain, separated via a long spacer (11 methylene-groups) from the norbornene, whereas monomer XIII has two relatively short (CH2)2(CF2)4-side chains (Fig. 11). Homopolymers and block copolymers were synthesized with one fluorinated monomer (XII or XIII) and one non-fluorinated non-liquid crystalline monomer (NBDE or COEN) with the Schrock-type initiators 4 and 5, respectively, leading to microphase-separated block copolymers. Table 9 and Table 10 summarize the physico-chemical properties of the homopolymers and block copolymers. 

Properties Fluorocarbons are chemically inert, nonflammable, and stable to heat up to 260-315C. They are denser and more volatile than the corresponding hydrocarbons and have low refractive indices, low dielectric constants, low solubilities, low surface tensions, and viscosities comparable to hydrocarbons. Some are compressed gases and others are liquids. 

Properties Colorless, volatile crystals. Sublimes, triple point 64.0C (1134 mm Hg), mp 64.5C (2 atm), d 5.06 (25C). Soluble in liquid bromine, chlorine, carbon tetrachloride, sym-tetrachloroethane, and fluorocarbons. Reacts vigorously with water, alcohol, ether, and most metals. Vapor behaves as nearly perfect gas. 

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