Surfactants fluorocarbon based

Guan, Z. and DeSimone, J. M. (1994) Fluorocarbon-Based Heterophase Polymeric Materials. 1. Block Copolymer Surfactants for Carbon Dioxide Applications, Macromolecules 27, 5527-5532. 

Yet, some commercial fluorocarbon-based displacement drying fluids are augmented with surfactants whose function is to chelate with the water so that it does not form emulsions with the fluorocarbon. Surfactant-fluorocarbon compositions have been patented to alleviate this condition, especially on non-metallic surfaces. Useful surfactants are ... 

Woods et al. [95] have studied the influence of the fluorocarbon-based polymer processing additive (PEA) Dynamar FX 9613/5920A on the surface and optical properties of polyolefin plastomer blown film by means of XPS and SSIMS. The same techniques were used to study the effect of Dynamar FX 9613 on the surface properties of HDPE [96]. Migration of fluorinated processing aids in HDPE film was also studied by XPS and ATR-FTIR [97]. Lens et al. [98] have reported an XPS study of the orientation of molecules of anionic surfactants, such as... 

The thermal stability of fluorinated surfactants is based on the outstanding stability of the fluorocarbon hydrophobe. Fluorocarbons are usually more stable than the corresponding hydrocarbons [6]. Other functional groups of the surfactant are usually less stable than the fluorocarbon group and may lower the thermal stability of the fluorinated surfactant. Hence, not all fluorinated surfactants are thermally stable. Perfluoroalkanecarboxylic acids and perfluoroalkanesulfonic acids are the most stable fluorinated surfactants. Their salts decompose more readily, however, than the parent free acids. 

Surfactants and Colloids in Supercritical Fluids Because very few nonvolatile molecules are soluble in CO2, many types of hydrophilic or lipophilic species may be dispersed in the form of polymer latexes (e.g., polystyrene), microemulsions, macroemulsions, and inorganic suspensions of metals and metal oxides (Shah et al., op. cit.). The environmentally benign, nontoxic, and nonflammable fluids water and CO2 are the two most abundant and inexpensive solvents on earth. Fluorocarbon and hydrocarbon-based surfactants have been used to form reverse micelles, water-in-C02... 

Finally, we have designed and synthesized a series of block copolymer surfactants for C02 applications. It was anticipated that these materials would self-assemble in a C02 continuous phase to form micelles with a C02-phobic core and a C02-philic corona. For example, fluorocarbon-hydrocarbon block copolymers of PFOA and PS were synthesized utilizing controlled free radical methods [104]. Small angle neutron scattering studies have demonstrated that block copolymers of this type do indeed self-assemble in solution to form multimolecular micelles [117]. Figure 5 depicts a schematic representation of the micelles formed by these amphiphilic diblock copolymers in C02. Another block copolymer which has proven useful in the stabilization of colloidal particles is the siloxane based stabilizer PS-fr-PDMS [118,119]. Chemical... 

K. Stabler, J. Selb, F. Candau, Multicompartment polymeric micelles based on hydrocarbon and fluorocarbon polymerizable surfactants, Langmuir 15 (1999) 7565-7576. 

Having shown that ionic/nonionic surfactant mixtures show negative deviations from ideality (when both components are hydrocarbon—based) and fluorocarbon/hydrocarbon—based surfactant mixtures show positive deviations from ideality, what would a ionic fluorocarbon/nonionic hydrocarbon surfactant pair be expected to do In one example of this case (57). the electrostatic stabi1ization forces overcome the hydrophobic group phobicity effects and negative deviation from ideality is observed. 

AFFF) A fire extinguishing foam based on blended hydrocarbon and fluorocarbon surfactants a rapidly spreading foam used on hydrocarbon fires. See also Fluor-oprotein Foam, Film Forming Fluoroprotein Foam, Alcohol Resisting Aqueous Film Forming Foam. 

The large majority of surfactants can be classified as hydrocarbon types, which means that the hydrophobe is a hydrocarbon. There is another class of surfactants, differentiated by the name fluorosurfactant, that uses a fluorocarbon instead of a hydrocarbon as the hydrophobe. Typically, the fluorocarbon is based on -(CF2) F where the number-averaged value of n 8 and effectiveness and efficiency of fluorosurfactants are sensitive functions of... 

Fluorinated surfactants (or fluorosurfactants, i.e., surfactants with hydrophobic tails comprising a fluorocarbon moiety) provide an alternative means of achieving extremely stable PFC emulsions, as they can provide very low PFC/water interfacial tensions [cr , another factor in Eq. (2)]. d s yet, this option has not been developed, in part because of the added cost involved in the evaluation for approval of a novel active excipient. A further means of effectively increasing the stability of EYP-based PFC emulsion consists of supplementing standard phospholipids with mixed fluorocarbon-hydrocarbon diblock compounds, such as 14 or 15. Such diblocks, which have fluorophilic-lipophilic amphiphilic properties, are expected to improve the adhesion of the phospholipid film onto the PFC droplet. 

Polyester- and polyether-based rigid urethane foams generally require a surfactant, whether expanded with COj from the water-isocyanate reaction, or with an inert blowing agent such as fluorocarbon. Without surfactant the foam may collapse or have a coarse cell structure. Castor-oil-based systems generally do not require surfactants, but better results will be obtained if they are used (20). 

F.S. Xiao, Ordered Mesoporous Silica-based Materials Templated from Fluorocarbon-Hydrocarbon Surfactant Mixtures and Semi-fluorinated Surfactants. Curr. Opin. Colloid Interface Sci., 2005, 10, 94-101. 

Another approach to use AOT as a surfactant for CO2 microemulsion consists in mixing AOT with a PFPE-based surfactant. This may seem quite disconcerting at first sight, as fluorocarbons and hydrocarbons are notoriously known to be immiscible. However Fulton et aL (67) reported microemulsion formation by mixing 15 mM of AOT and 30 mM of PFPE-PO4 up to w = 12. These systems could be successfully used as micro reactors to synthesize metallic silver (3, 4) and copper nanoparticles (5) and to carry out catalytic hydrogenations (5). Eastoe et al also showed that hydrocarbon surfactants analogous to AOT with branched tails were CO2 compatible (68). More detail is given in section 3 below. 

Based on the success of these fluoro-sulfosuccinates described above di-fluorocarbon phosphates have also been investigated. In terms of synthesis and raw materials costs these surfactants have significant advantages over the sulfosuccinates. Surfactants of this kind have also been studied by DeSimone et al (27 c), and the synthesis and purification are described elsewhere (27b, c). Detailed SANS experiments are described in these papers (27b, c), and it is clear that surfactants of diis kind stabilize aqueous nano-droplets. Hence, anionics other than sulfosuccinates may be employed in water-in-C(>2 microemulsions. Significantly, one of these conq>ounds (di-HCF6-P, see ref 27 b) stabilizes microemulsions in liquid CO2 at vapor pressure a potentially useftil result that may be of importance in facilitating applications. 

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