Solute partition study in aqueous sodium dodecyl sulfate micellar solutions for some organic reagents and metal chelates

The partition constants (K _d) have been estimated for nitrophenols, thiazolylazo dyestuffs and metal chelate compounds into the sodium dodecyl sulfate (SDS) micellar phase at an ionic strength of 0.10M [(H⁺, Na⁺)Cl^–] and at 20 °C. The equilibrium partition data obtained by batch-wise solution spectrophotometry (equilibrium shift method) agree well with those by the micellar electrokinetic capillary chromatography (MECC) with the SDS micellar pseudo-stationary phase. The MECC clearly discriminates a very small difference (0.03) in the logK _d values of some metal chelates. The plot of theK _d values with the van der Waals volume of the solute molecules obviously shows the leveling-off of theK _d values over solute size near 110 ml/mol, which seems to be consistent with the results obtained in the Triton X-100 micellar system. This phenomenon arises most probably from the rigidity of the micellar pseudo-phase (a micellar volume-constraint effect) in sharp contrast with true two-phase partitioning such as solvent extraction systems.     

Quantitative confirmation of the crystal-amorphous interphase in semicrystalline poly(vinylidene fluoride) and poly (vinylidene fluoride)/poly (ethyl methacrylate) blends

Dielectric and thermal characterizations were performed for poly (vinylidene fluoride) (PVDF)/poly (ethyl methacrylate) (PEMA) blends of different composition. The characteristics of PVDF β relaxation were shown to be little affected in the semicrystalline blends with PEMA. The relaxation strength, however, depends strongly on the PEMA content and a linear relation was found between the intensity of the β relaxation and the weight fraction of the PVDF crystal-amorphous interphase. Phase structures of the PVDF/PEMA blends are also proposed. © 1994 John Wiley & Sons, Inc.     

Specific retention behaviour of metal (III) tetraphenylporphyrins in non-aqueous,reversed high-performance liquid chromatography

Summary The Co(II), Ni(II), Fe(III) and V(IV) complexes of tetraphenylporphine (TPP) can be eluted at short retention times from a LiChrosorb RP-18 column with pure ethanol. However, both Mn(III) and Co(III) complexes of metal TPP chloride type are so strongly retained on the column that they cannot be eluted. While the retention of other metal teraphenylporphine complexes was not affected, that of the metal(III) complexes of the TPP chloride type especially MnTPPCl and CoTPPCl, decreases dramatically with an increase in the concentration of NH₄Cl added into the mobile phase; a linear relationship between logk' and log[NH₄Cl], with the slope of about–1, has been observed for these two metal(III) complexes in the NH₄Cl concentration range from 2.5×10^–4 to 1.3×10^–2 mol/l. Thus, the specific control of the retention of the metal(III) complexes is enabled by conditioning the NH₄Cl content of the mobile phase, and the chromatographic separation is demonstrated.     

Possible evidence for the entrance channel effect in reactions leading to 170W*

The decay of ¹⁷⁰W^* formed in reactions with two different projectile - target combinations was studied. The observed differences in the average number of emitted neutrons suggest an entrance channel effect at the highest excitation energy and angular momentum. It may be explained by different excitation energies of the equilibrated system, resulting from the emission of pre-equilibrium α-particles during a longer fusion time, in the more symmetric reaction. Received: 30 October 1997     

Mobile customer model with retrials

A cellular system consisting of small zones is studied. Since their zones are small, the change of the number of mobile customers in a cell influences the performance. The hand-off failure probability and blocking probability may be important as the performance measures. In this paper, we consider the retrial behavior of customers who meet the hand-off failure and blocking. We classify customers into three types: the retrial resignation type, the ordinary retrial type and the persistent retrial type. We evaluate the effect of the existence of mobile customers with retrials.     

Concentration of polyaromatic hydrocarbons in water to sodium dodecyl sulfate-gamma-alumina admicelle

Polyaromatic hydrocarbons (PAHs) in water were concentrated into sodium dodecyl sulfate (SDS)-gamma-alumina and di-2-ethylhexyl sodium sulfosuccinate (Aerosol-OT, AOT)-gamma-alumina admicelles. The comparison of the binding constants (Kad[={adsorbed concentration of the solute (mol/g surfactant)}/{the concentration in the bulk aqueous phase (mol/ml)}] indicated almost the same extraction abilities of the both admicelles. However, better and more reproducible recovery was obtained in the concentration of PAHs into the SDS-gamma-alumina admicelle. PAHs in tobacco smoke that were trapped in water were successfully concentrated into SDS-gamma-alumina admicelle for the HPLC analysis.     

Preparation of self-assembled fluorinated molecular aggregates, fluorescein nanocomposites: an extremely enhanced light absorption in nanocomposites

Self-assembled fluorinated molecular aggregates formed by fluoroalkyl end-capped N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomers, N,N-dimethylacrylamide oligomers, and acrylic acid oligomers in methanol could selectively recognize fluoresceins as guest molecules to form a new class of fluorinated aggregates-fluorescein nanocomposites. These fluorinated fluorescein nanocomposites that are obtained exhibit an extraordinarily enhanced light absorption (_max ca. 440 nm) compared to that (_maxs 452, 480 nm) of the parent fluorescein in the absence of fluorinated aggregates.     

Photografting of polymers onto nanosized silica surface initiated by eosin moieties immobilized onto the surface

The photograft polymerization of various vinyl monomers onto nanosized silica surfaces was investigated. It was initiated by eosin moieties introduced onto the silica surface. The preparation of the silica with eosin moieties was achieved by the reaction of eosin with benzyl chloride groups on the silica surface.These were introduced by the reaction of surface silanol groups with 4‐(chloromethyl)phenyltrimethoxysilane in the presence of t‐butyl ammonium bromide as a phase‐transfer catalyst. The photopolymerization of various vinyl monomers, such as styrene, acrylamide, acrylic acid, and acrylonitrile was successfully initiated by eosin moieties on the silica surface in the presence of ascorbic acid as a reducing agent and by oxygen. The corresponding polymers were grafted from the silica surface. The grafting efficiency (percentage of grafted polymer to total polymer formed) in the photoinitiation system was much larger than that in the radical polymerization initiated by surface radicals; these radicals were formed by the thermal decomposition of azo groups introduced onto the silica surface. It was found that the polymer‐grafted silica gave stable dispersions in good solvents of grafted polymer and the wettability of the surfaces can be easily controlled by grafting of polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 600–606, 2005