Lithium perfluorooctanesulfonate

Selectivity differences for the alkane sulfates and sulfonates are not particularly sensitive to changes in the identity of the counterion or the alkyl chain length [204,209]. Sodium dodecyl sulfate is representative of this group. On the other hand, the perflu-orooctanesulfonate and N-alkyl-N-methyltaurine surfactants afford different selectivity to sodium dodecyl sulfate [197,202,208]. Lithium perfluorooctanesulfonate has differ-... 

Lamont, R. and Ducker, W., Organized structure of lithium perfluorooctanesulfonate at the graphite-solution interface, 7. Colloid Interface ScL, 191, 303-311 (1997). 

Changes in zeta potential and turbidity of iron(III) oxide hydrate sols flocculated with lithium perfluorooctanesulfonate (LiFOS) are shown in Fig. 5.11. The nonionic surfactants NF7 and NP7.5 redispersed the sols. However, the anionic hydrocarbon surfactant LiDS (lithium dodecyl sulfate) had no significant effect. Accordingly, sols flocculated by LiDS were redispersed by a nonionic surfactant, NF7, but not by the anionic surfactant LiFOS (Fig. 5.12). 

The pseudophase model (see Section 6.2) for micellar solutions makes it possible to establish a partitioning coefficient for the partitioning of the solubilizate between the aqueous solution and the micellar pseudophase. Treiner et al. [206-208] studied partitioning of alcohols and phenol in an aqueous solution of a fluorinated surfactant or of mixed anionic hydrocarbon and fluorocarbon surfactants. The fluorinated surfactants used in their studies were potassium or sodium perfluorooctanoate and lithium perfluorooctanesulfonate. 

Fluorinated surfactants, such as lithium perfluorooctanesulfonate, potassium perfluoroalkanesulfonate, and an amine perfluoroalkanesulfonate, are effective wetting agents in etching solutions for plastics. 

Kato et al. [310] studied emulsion polymerization of styrene in the presence of sodium dodecyl sulfate and lithium perfluorooctanesulfonate. The fluorinated surfactant decreases the polymerization rate and the molecular weight of the polymer formed. 

Tamori et al. [290] used electric birefringence to estimate the micellar size and shape in mixed-surfactant solutions containing hexaoxyethylene glycol dode-cyl ether and lithium perfluorooctanesulfonate or lithium dodecyl sulfate. 

Moreover, addition of lithium- or tetraalkylammonium perfluorooctanesulfonate doubles or triples the mean number of achievable deposition/dissolution cycles with LiCl04 in PC [372]. 

The exchange of surfactant monomers between the micellar and the monomeric state is diffusion controlled for monomers with hydrophilic counterions. The exchange rate is slower for monomers with hydrophobic counterions. For lithium and substituted ammonium salts of perfluorooctanesulfonic acid [76], the values of the micellar distribution curve, a ln, increased with increasing hy-drophobicity of the counterion or with a decrease of temperature. Both the association rate constant, k /n, and dissociation rate constant, k /n, decreased with increasing counterion hydrophobicity. The increase in k /n values was larger than the decrease in cmc values, suggesting that hydrophobic counterions form a barrier to the monomer exchange process. 

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