SANS-measurements on micellar solutions of perfluoro-detergents

Small angle neutron scattering studies on micellar systems part 1. Ammonium octanoate, ammonium decanoate and ammonium perfluoroocatanoate

“…The stiffness of the chain may perhaps be more easily accommodated if each line of APFO molecules is twisted to form a helix (see [8]). If the radial surface of the cyKnder is assumed to be the external surface of the head groups then we find for the area per head group a value of 70 A 2: this is slightly larger than the values of 60 ~2 quoted by Hoffmann et al [6]. It may also be an underestimate since there must be some distortion at the ends of the cylinder.…”

“…For example, the specific refractive index increment of sodium perfluoro-octenyl oxy benzene sulphonate was found by Smith [5] to be 0.060 cm 3 g-i at a wavelength of 560 nm and a light scattering study showed the micelles in water to be very small, although in 1.8 x 10 -2 mol dm -3 sodium chloride rod shaped micelles with a micellar weight of order 106 were formed. An alternative technique for examining micellar systems, however, is provided by small angle neutron scattering and this method has been used by Hoffmann et al [6] for the examination of tetramethylammonium perfluorooctane sulphonate and diethylperfluorononanoate. The former material was found to form rod-like micelles and the latter disc-like micelles.…”

Small angle neutron scattering measurements on micellar solutions of perfluor detergents

“…These early studies prompted us to begin SANSstudies on these systems, the first results of which we have already published [5]. In the meantime phase diagrams of some of the systems which we had studied previously have been reported by Lindman and Fontell [6].…”

“…After the usual corrections for background scattering and incoherent scattering, the coherent scattering rates Z (Q) were obtained [5]. Q is the momentum transfer (4 x/l) sin (8/2) with the full scattering angle 8 and the wavelength ,l of the neutrons (10 A in our experiments).…”

Formation of rodlike micelles of dimethyloleylamine oxide in aqueous solutions: effects of addition of HCl and NaCl on the micelle size and the intermicellar interaction

“…All these micelles are supposed to be spherical, but no attempts to derive intermicellar potentials have been made. Small angle neutron scattering from aqueous solutions of some ionic surfactants having bulky and specific counterions was observed and showed evidence for the formation of rodlike micelles in water, together with the existence of neighboring orders arising from intermicellar interaction [37,38]. They are tetramethylammonium perfluoroctane sulfonate [37] and cetylpyridinium salicylate [38].…”