Role of the Cosurfactant in the CTAB/Water/n-Pentanol/n-Hexane Water-in-Oil Microemulsion. 1. Pentanol Effect on the Microstructure

Abstract

The microstructure of the quaternary water-in-oil microemulsion CTAB/water/n-pentanol/n-hexane has been investigated by means of the pulsed gradient spin-echo NMR technique over a wide range of composition. The composition of the continuous organic phase and of the interfacial phase has been determined through the analysis of the n-pentanol self-diffusion coefficient. The size of the reverse aggregates has been evaluated from the CTAB self-diffusion coefficient. The correlation of the reverse micellar size with interfacial composition has therefore been possible. Results coming from both water dilution lines and interface dilution lines have been analyzed according to suitable models. A "master plot", i.e., a graphical representation that allows us to display the data collected at all the possible compositions of the four components system, is also proposed.

Protein Stability in Reverse Micelles

“…The 19 Fspectra were compared at the stability extremes shown in Figure 2. Theo nly resonances that change with temperature are from the folded and the unfolded forms.T hese and other data [7d] confirm the lack of protein-alkane solvent interactions.T he 15 N-1 HH SQC data on SH3 in buffer and in both reverse micelle systems ( Figure S3) indicate that encapsulation maintains the structural integrity of SH3, an observation consistent with studies of other proteins.…”

“…Radii of the micelles, r rm , and the aqueous phases, r aq ,w ere calculated using Equation (6), the viscosity of isooctane [14] and the contour length of CTABr [15] (15.4 ) and 10MAG/LDAO (ca. 12 ).…”

Using spin polarised positive muons for studying guest molecule partitioning in soft matter structures

“…However, the hydrocarbon tail of the alcohol contributes to the hydrophobic interaction, thus to the surfactant hydrocarbon volume. Such a local packing of cosurfactant and surfactant sets the spontaneous curvature of the interface, its flexibility and preferred size of noninteracting aggregates [66][67][68][69]. In this way the lower-curvature (smaller head-group area) structures are stabilized by added cosurfactant; e.g., the hexagonal phase gives way to the lamellar phase [51,64].…”

Circular dichroism of polynucleotides: Interactions of NiCl2 with poly(dA‐dT)·poly(dA‐dT) and poly(dG‐dC)·poly(dG‐dC) in a water‐in‐oil microemulsion

“…25,26 To define from a physico-chemical point of view the quaternary microemulsions (surfactant|cosurfactant|oil|water) it is necessary to know the value of three parameters: the surfactant concentration, the amount of solubilized water (W 0 5 [water]/[surfactant]) on which the dimensions of the droplets depend 27 and the amount of cosurfactant (P 0 5 [cosurfactant]/[surfactant]), which modifies the spontaneous curvature of the interface and the viscosity of the medium. 28 Our research group, in several previous studies, has utilized the quaternary w/o lE CTAB|n-pentanol|n-hexane|water (CTAB 5 hexadecyltrimethylammonium bromide) of the following characteristics: [CTAB] 5 0.10 M; W 0 5 15; P 0 5 8.5. This system can easily dissolve in its aqueous microdomain the synthetic model duplex polynucleotides poly(dA-dT)Ápoly(dA-dT) and poly(dGdC)Ápoly(dG-dC), from now on indicated, respectively, as polyAT and polyGC.…”