Fluorooctyl

Examples of perfluoroalkyl iodide addition to the triple bond include free radical addition of perfluoropropyl iodide to 1 -heptyne [28] (equation 21), thermal and free radical-initiated addition of lodoperfluoroalkanesulfonyl fluorides to acetylene [29] (equation 22), thermal addition of perfluoropropyl iodide to hexa-fluoro 2 butyne [30] (equation 23), and palladium-catalyzed addition of per-fluorobutyl iodide to phenylacetylene [31] (equation 24) The E isomers predominate in these reactions Photochemical addition of tnfluoromethyl iodide to vinylacetylene gives predominantly the 1 4 adduct by addition to the double bond [32] Platinum catalyzed addition of perfluorooctyl iodide to l-hexyne in the presence of potassium carbonate, carbon monoxide, and ethanol gives ethyl () per fluorooctyl-a-butylpropenoate [JJ] (equation 25)... 

Dispersion polymerizations of methyl methacrylate ntUizing poly(l,l,-dihydroper-fluorooctyl acrylate) as a steric stabilizer in snpercritical CO2 were carried out in the presence of helium. Particle size and particle size distribution were found to be dependent on the amonnt of inert helium present. Particle sizes ranging from 1.64 to 2.66 pm were obtained with varions amounts of helium. Solvatochromic investigations using 9-(a-perflnoroheptyl-p,p-dicyanovinyl)julolidine indicated that the solvent strength of CO2 decreases with increasing helium concentration. This effect was confirmed by calcnlations of Hildebrand solubility parameters (Hsiao and DeSimone, 1997). 

It was previously reported that the homopolymer surfactant PFOA successfully stabilized poly(methyl methacrylate) (PMMA) dispersion polymerizations (DeSimone et al., 1994 Hsiao et ah, 1995), but was not successful for styrene dispersion polymerizations (Canelas et al., 1996). In these styrene polymerizations, the C02 pressure used was 204 bar. However, later studies showed that both PFOA and poly(l,l-dihydroper-fluorooctyl methacrylate) (PFOMA) could stabilize polystyrene (PS) particles (Shiho and DeSimone, 1999) when a higher pressure was used. These polymerizations were conducted at 370 bar, 65 °C, and the particle size could be varied from 3 to 10 pm by varying the concentration of stabilizer. These homopolymer surfactants are less expensive and easier to synthesize than block copolymer surfactants and provide access to a large range of particle sizes. 

Hsiao YL, Maury EE, DeSimone JM, Mawson S, Johnston KP. Dispersion polymerization of methyl methacrylate stabilized with poly(l,l-dihydroper-fluorooctyl acrylate) in supercritical carbon dioxide. Macromolecules 1995 28 ... 

The hydrophobic monomers styrene and MMA were copolymerized with the sodium salt of vinylbenzylsulfosuccinic acid as a polymerizable surfactant grafting of the surfactant onto the particles was estimated to be about 50-75% [51]. A polymerizable surfactant was formed by the esterification of hydroxypropylmethacrylate or hydroxyethyhnethacrylate with succinic anhydride [53]. However, in addition to the surfmer, sodium dodecyl sulfate (SDS) was employed to provide a sufficient stability to the latexes. A mono-fluorooctyl maleate surfactant was used to stabilize the polymerization of styrene in miniemulsion [55]. Although the polymerizable moiety was not fixed at the end of the fluorinated chain (the hydrophobe part), the surfactant could be copolymerized with the styrene monomer. Subsequently, on comparison of the infrared (IR) spectra (vibration of -CF2 and -CFj) before and after dialysis, it was estimated that 92% of the surfactant had remained grafted post-dialysis. 

The surface energy and tribological performance of poly (lH,lH-pentadeca-fluorooctyl methacrylate) fluorohydrocarbon surfactant were compared with several other types of slider coatings. The surface energy of the fluorinated acrylate polymer was the lowest, and it provides the best compromise for reduction of both lubricant transfer and scratches. The improvement is consistent with a reduction in the adhesion stress by the low-surface-energy coatings on the slider. 

SANS has been used widely to study the way in which these molecules self-assemble into aggregates (micelles, microemulsions etc.) in aqueous media [4, 26, 27]. The possibility of forming analogous micelles in SCFs has been debated for a decade [28,29] and has subsequently been demonstrated via SANS [30, 31], SAXS [32], and other techniques [33]. These micelles consist of a CO2-phobic core surrounded by a C02-philic (fluoropolymer) shell and Fig. 7.4 shows a schematic representation of such micellar aggregates both in aqueous and in C02-based systems. SANS has illustrated the way in which polystyrene may be solubilized by means of polystyrene-poly(fluorooctyl acrylate) (PS-PFOA) stabilizers, which form... 

Lim, K.T., Lee, M.Y., Moon, M.J. et al. (2002) Synthesis and properties of semifluorinated block copolymers containing poly(ethylene oxide) and poly(fluorooctyl methacrylate) via atom transfer radical polymerization. Polymer, 43,7043-7049. 

Because Pluronic F-68 has caused adverse reactions in some patients, fluorinated surfactants are being developed to replace Pluronic F-68 as the sole emulsifier. Attempts to use perfluoroalkylated surfactants derived from galactose, glucose, maltose, and related polyols as single surfactants were unsuccessful [125,127,139,143,155]. However, a study of perfluoroalkylated fatty acid monoesters of trehalose and sucrose (Fig. 13) [144,145] showed that 6-0-[3 -(per-fluorooctyl) propanoyl)-o ,Q -trehalose can emulsify perfluorodecalin and form stable emulsions in the absence of Pluronic F-68. 

Fulton and Pfund [20] used small-angle X-ray scattering (SAXS) to show that a polymer with a C02-philic poly(fluorooctyl acrylate) backbone and C02-phobic poly(ethylene oxide) grafts formed small aggregates in CO2. 

---