Physicochemical properties of aqueous solutions of fluorinated surfactants

Abstract

The surface tension and the solubility of aqueous solutions of fluorinated surfactants (CJBVhSOsM, C7F15-COOM, etc.) have been measured. The cmc's and the Krafft points of the fluorinated surfactants were determined from these data. The cmc of fluorinated surfactant is close to that of ordinary surfactant whose hydrocarbon chain length is about 1.5 times longer than a fluorocarbon chain. This relation is explained assuming the free energy change of transferring the -CF2group from the singly dispersed state (aqueous environment) to the micellar state is 1.6kT. The surface tension of several fluorinated surfactants whose chain length is longer than ~8 or 9 was not depressed as low as expected. This is because the Krafft points of these surfactants are higher than the experimental temperature at which the hydrated solid form precipitates and the concentration of singly dispersed material does not increase. If the Krafft point were low, the surface tension would have attained as low as 20 dyn/cm above the cmc, as in the case of ethanolammonium perfluorooctanesulfonate. The correlation between the Krafft points and the structure of fluorinated surfactants is explained by the theory that a Krafft point is a melting point of hydrated solid agent.

Physicochemical Properties of Oleic Acid-Based Partially Fluorinated Gemini Surfactants

“…It has been reported that the cmcs of fluorinated surfactants are close to those of hydrogenated surfactants whose hydrocarbon chain length is ca. 1.5 times longer than the fluorocarbon chain 25 . On the basis of this empirical rule, in the case of CC-9,9-EsH2F4, for example, the effective hydrocarbon chain length from the ester unit is estimated as 4 1.5 2 8.…”

“…This is the first report focusing on the physicochemical properties of oleic acid-based gemini surfactants in aqueous solution as a function of the hydrophobic chain type. We have assessed the dilute aqueous solution properties at pH 9 in the presence of 10 mmol dm 3 NaCl at 25 by means of static surface tension, pyrene fluorescence, and dynamic light scattering DLS measurements. We have also studied the temperature-concentration phase diagrams of the surfactants disodium salts at concentrations up to 80 wt .…”

Congener specific organic carbon normalized soil and sediment-water partitioning coefficients for the C1 through C8 perfluoroalkyl carboxylic and sulfonic acids

“…We do note, however, that previous work has established both the effects of chain branching and the head group counterion (e.g., H + , Na + , Li + , K + , NH 4 + , Mg 2+ ) on the physicochemical properties of PFAs. [130] Although only one branched PFA was available for testing in this historical study (the terminal monomethyl branched C 8 PFCA 88), both branching and the counterion identity had significant effects on properties such as the critical micelle concentrations and Krafft points. Consequently, future work will need to better define the counterion effects on PFA behavior, but with our current level of uncertainty on this front, a default to assessments with the acid form seems the most productive first step.…”

Synthesis and Solution Properties of Adamantane Containing Quaternary Ammonium Salt-type Cationic Surfactants: Hydrocarbon–based, Fluorocarbonbased and Bola–type

“…The aggregates may be small premicelles such as dimers or trimers. It is known that the CMC for fluorocarbon-type surfactants follows an equivalence of 1 CF 2 to 1.5 CH 2 units of hydrocarbon-type surfactants 18 . Therefore, it is expected that the CMC of fluorocarbon-type C 6 F C 3 AdAB be equal to that of hydrocarbontype C 12 AdAB; in other words that its alkyl carbon number is1.5 times the carbon number in the fluorocarbon chain, in addition to the 3 carbons from the propyl chain.…”