Fluorinated nonionic

Water-in-fluorocarbon emulsions, stabilised with fluorinated nonionic surfactants, were investigated by small angle neutron scattering (SANS) spectroscopy [8,99]. The results indicated that the continuous oil phase comprised an inverse micellar solution, or water-in-oil microemulsion, with a water content of 5 to 10%. However, there was no evidence of a liquid crystalline layer at the w/o interface. A subsequent study using small angle x-ray scattering (SAXS) spectroscopy gave similar results [100]. 

The above results demonstrate that partially fluorinated nonionic surfactants, having a fluorinated hydrophobic chain and a nonfluorinated poly(ethylene oxide) polar chain, can be successfully used to obtain mesoporous materials with controlled morphology and pore size. The specific surface areas can be high, similar to MCM-41 materials obtained using hydrocarbon surfactants. 

Note that the pore walls of the material templated using QFi7S02[C3H7] N(EO)ioH, indicated in Table 11.2, are thicker than those of MCM-41 materials [13]. The pore walls are also thicker than those obtained when using fluorinated cationic surfactants [62, 63], which resemble MCM materials, or when using nonionic surfactants with partially fluorinated alkyl tails [53]. However, the main characteristics of the materials described here are similar to those obtained by using E(CE2)s(EO)io or F(CE2)6(EO)i4 fluorinated nonionic surfactants [64, 65]. 

The fact that a determined from molecular size coincides with that obtained from surface tension fits (Table 4.5) is very nseful for applications. Thus, when fitting experimental data, we can use the value of a from molecular size, and thus to decrease the number of adjustable parameters. This fact is especially helpful when interpreting theoretically data for the surface tension of surfactant mixtures, such as SDS + dodecanol [54] SDS + CAPB [59], and fluorinated + nonionic surfactant [61]. An additional way to decrease the number of adjustable parameters is to employ the Traube rule, which states that increases with. 025kT when a CH2 group is added to the paraffin chain for details see Refs. [54,55,60]. 

RfCH=CH(CH2)90H, Rf=C6F 3 or C8F17, prepared by reacting the perfluo-roalkyl iodide with undecenol using copper(I) chloride and ethanolamine catalysis [254]. The reaction product was deacetylated in a methanol-triethylamine-wa-ter mixture to give the fluorinated nonionic surfactant (see Section 10.4). 

Selve et al. [32] synthesized fluorinated nonionic surfactants with a two-chain polyoxyethylene hydrophilic head linked to the hydrophobe via an amide bond, F(CF2)i(CH2), C(0)N[(C2H40) CH3]2. They calculated the area A per surfactant molecule adsorbed on the air-water interface from the slope of the surface tension curve using the Gibbs equation [Eq. (13)]. The area A increases with increasing number of oxyethylene units for both fluorinated and hydrocarbon sur-... 

Selve et al. [32] prepared fluorinated nonionic surfactants with a two-chain polyoxyethylene hydrophilic head linked to the hydrophobe via an amide bond. 

Krafft points for fluorinated nonionic surfactants have not been reported. However, the widespread view that nonionic surfactants do not have a BCrafft point is incorrect. Although only a few nonionic surfactants exhibit a Krafft point, an implication that the Krafft point is related to the ionic charge of a surfactant is mis-... 

Funasaki and Hada [116] examined the mutual solubility of a fluorinated nonionic surfactant [(CF3)2CF]2C=C(CF3)0(CH2CH20) CH3 (NFE, average n — IS.4) and a nonionic hydrocarbon chain surfactant CH3(CH2)u-0(CH2CH20), H (DEm, w = 5, 7, 9, or 25). Curves of the surface tension plotted against the logarithm of total surfactant concentration for mixtures of NFE and DE7 are shown in Fig. 7.34. The constancy of surface tension beyond cmc (curve a) indicates that DE7 was highly pure, unlike NFE (curve f), which is difficult to purify and therefore contained impurities. The cmc values of NFE-DE7 mixtures exhibited a maximum at a mole fraction of 0.327 for DE7. The relation between the surface tension and the mole fraction of monomeric DE7 in the mixture of NFE and DE7 monomers is shown in Fig. 7.35 with open circles. The filled circles show the surface tension at about 10-fold concentrations above cmc as a function of DE7 mole fraction in the whole system. A plateau region in the micellar composition curve indicates the coexistence of two kinds of mutually saturated mixed micelles. 

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