Counterion effect on the phase behavior of perfluoropolyether carboxylates: micelles and liquid crystals in water

Caboi, Francesca; Chittofrati, A.; Lazzari, Paolo; Monduzzi, Maura

doi:10.1016/s0927-7757(99)00260-5

Cited by 28 publications

(43 citation statements)

References 15 publications

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“…(5), with X b n2 ¼ molar fraction of Na n2 bound and X b n3 ¼ molar fraction of Na n3 (or n3 þ n4) bound: (a) Na n2=n3 ¼ 60=40 binary mixture; (b) Na n2=n3=n4 ¼ 47=33=20 ternary mixture. sodium surfactants with respect to the ammonium analogous [9].…”

Section: Discussionmentioning

confidence: 99%

Mixed micelles of homologous perfluoropolyether anionic surfactants in water

Mele¹,

Murgia²,

Monduzzi³

2004

Journal of Fluorine Chemistry

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Section: Discussionmentioning

confidence: 99%

Mixed micelles of homologous perfluoropolyether anionic surfactants in water

Mele¹,

Murgia²,

Monduzzi³

2004

Journal of Fluorine Chemistry

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“…The K against C plots for the two surfactants show no maxima thereby ruling out the possibility of formation of pre-micellar aggregates, nevertheless both k vs. C and K vs. C plots show that micellization is not sharp. It is commonly accepted that degree of counter ion dissociation (a) of micelles could be approximately obtained from the ratio of slopes of post-and pre-micellar line segments [36][37][38]. Keeping in mind the approximations on which the practiced method is based, the said values for the two surfactants are almost similar quite contrary to what is expected on account of reported higher aggregation number of cetylpyridinium chloride than its dodecyl homologue.…”

Section: Equilibrium Propertiesmentioning

confidence: 97%

Temperature dependence of transport and equilibrium properties of alkylpyridinium surfactants in aqueous solutions

Bhat

Dar

Amin

et al. 2007

The Journal of Chemical Thermodynamics

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“…Like conventional nonionic surfactants such as poly(oxyethylene), perfluorosurfactants also show a rich phase behavior in aqueous solutions [21][22][23][24][25]. These surfactants in aqueous solution show an upper miscibility gap with a lower critical point in the temperature-composition diagram.…”

Section: Introductionmentioning

confidence: 99%

Small-angle X-ray scattering (SAXS) study on nonionic fluorinated micelles in aqueous system

Shrestha

Sharma

Sato

et al. 2007

Journal of Colloid and Interface Science

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We have investigated the self-organization structures of perfluoroalkyl sulfonamide ethoxylate, C(8)F(17)SO(2)N(C(3)H(7))(CH(2)CH(2)O)(10)H, a nonionic fluorinated surfactant in aqueous system by small-angle X-ray scattering (SAXS) technique. Structural modulation of the nonionic fluorinated micelle induced by temperature change, surfactant concentration, and the added fluorinated oils have been systematically studied. The SAXS data were analyzed by the indirect Fourier transformation (IFT), and the generalized indirect Fourier transformation (GIFT) depending on the volume fraction of the surfactant. Various plausible classical model calculations have been performed to confirm the consistency of the GIFT analysis of the SAXS data. Upon successive increase in temperature, the cylindrical micelles formed at lower temperatures undergo a continuous one-dimensional growth and ultimately near the cloud point an indication of flat planar like structural pattern is observed. The evolution in structure of particle near the demixing temperature may be due to onset of attractive interactions. The shape and size of the micelle is apparently unaffected by changing the surfactant concentration from 1 to 5 wt% at 25 degrees C. Nevertheless, addition of small amount of perfluoropolyether (PFPE) oil, of structure F(CF(2)CF(2)CF(2)O)(n)CF(2)CF(2)COOH (n approximately 21) modulate the micellar shape and size. Long cylindrical micelles eventually transform into globular like particles. The onset cylinder-to-sphere transition in the structure of micelles in the surfactant/water/oil system is probably due to amphiphilic nature of the oil, which tends to increase the spontaneous curvature. The lipophilic part of the oil tends to reside in the micellar core, whereas, the hydrophilic part goes close to the polar head group of the surfactant so that effective cross-sectional area per surfactant molecules increases and as a result spherical micelles tend to form. Perfluorodecalin (PFD) also decreases size of the micelles but its effect is poor compared to the PFPE oil.

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Counterion effect on the phase behavior of perfluoropolyether carboxylates: micelles and liquid crystals in water

Cited by 28 publications

References 15 publications

Mixed micelles of homologous perfluoropolyether anionic surfactants in water

Mixed micelles of homologous perfluoropolyether anionic surfactants in water

Temperature dependence of transport and equilibrium properties of alkylpyridinium surfactants in aqueous solutions

Small-angle X-ray scattering (SAXS) study on nonionic fluorinated micelles in aqueous system

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