Small angle neutron scattering of direct micelles in binary and ternary surfactantÈalcoholÈ surfactantÈD 2 O systems has been measured. The nonionic surfactant was poly(oxyethylene-23) lauryl ether D 2 O (C 12 E 23, commercial name : Brij 35) which was used at concentrations far beyond its critical micellar concentration : between 0.1 and 15 mass% (about 1.0 ] 10~3È1.5 ] 10~1 mol l~1). The alcohols were butan-1-ol, pentan-1-ol, hexan-1-ol, and heptan-1-ol at concentrations of about 0.25 mol l~1. The spectra could quantitatively be modelled by the PercusÈYevick integral equation method in combination with a core/shell model yielding detailed information about the size, the (ellipsoidal) shape, the aggregation number, the internal structure and the distribution of the micelles. The ternary systems were modelled with an additional parameter, the partition of the alcohol between the outer aqueous bulk and the inner micellar pseudo-phase. In the case of the pentanol system the partition coefficient inferred from NMR self-di †usion measurements was used to describe the scattering result.
A simple encapsulation technique is presented to produce highly phosphorescent, inert nanospheres that are suitable luminescent markers. It is based on the coprecipitation of phosphorescent ruthenium(II)-tris(polypyridyl) complexes and polyacrylonitrile (PAN) derivatives from a solution in N,N-dimethylformamide. The beads precipitate in the form of very small aggregates of spherical shape and a typical particle diameter of less than 50 nm. This process allows the encapsulation of phosphorescent and fluorescent dyes in an individual nanosphere provided that they are sufficiently lipophilic. Quenching by oxygen is negligible due to the use of PAN. The nanospheres were characterized with respect to their spectral properties (quantum yields of the luminophores, brightness, luminescence decay time), stability in aqueous buffered suspensions, and in terms of size, shape, and surface charge of the particles, as well as storage stability, quenching by oxygen, and dye leaching.
Ternary systems of dodecyltrimethylammonium bromide (C 12 TAB)/1-hexanol/water are examined for series with constant surfactant to alcohol molar ratios of n s /n a ) 8:2, 8:4, 8:6, and 8:8 at surfactant concentrations of c ) 6.167-61.67 g/L (0.02-0.20 mol/L). The methods used are conductivity measurements, differential refractometry, static and dynamic light scattering, small-angle neutron scattering, and X-ray scattering. Critical micelle concentrations (cmc) and the degree of dissociation of the micelles are determined by conductivity measurements. The refractive index increment is given for each series as well as static and dynamic lightscattering intensities plotted as a function of the surfactant concentration. From small-angle neutron-scattering experiments a detailed picture of the size and the geometry of the micelles could be obtained, whereas smallangle X-ray scattering allowed information about the thickness of the interfacial film to be inferred. A hypernetted chain calculation with solvent plus ion-averaged screened Coulombic potentials combined with an ellipsoidal core/shell model permitted a simultaneous and coherent description of all scattering results.
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