“…The extension of the different phases occurring in AG/water systems displays a rather weaker temperature dependence than do EO-based surfactants. As expected for a nonionic surfactant, solutions of AGs in water are insensitive toward the addition of salt. − There are several indications − that it is the complex isomerism of the carbohydrate head group that determines the physicochemical properties of AGs. 1 α- and β- d -glucose and model structures indicating how a hydrocarbon chain will be attached to the glucose molecule in the two cases. In α- d -glucose (left), the hydrocarbon chain is attached to the axial hydroxyl group (marked with an arrow) at carbon number one.…”
The n-octyl
β-d-glucoside/water binary phase diagram (temperature vs
concentration) and the aggregation
parameters of the individual phases have been determined.
n-Octyl β-d-glucoside forms four
different
phases together with water. At temperatures below 22 °C, there
is an isotropic solution region from neat
water extending up to almost 60 wt % n-octyl
β-d-glucoside. As the concentration is further
increased,
three liquid crystalline phases form in the following order:
hexagonal, cubic, and lamellar. At high surfactant
concentrations (>93 wt %) the lamellar phase is in equilibrium with
hydrated crystals. The hexagonal
phase disappears at temperatures slightly higher than 20 °C. The
solution region has been investigated
with 1H-NMR to deduce the self-diffusion coefficients of
both n-octyl β-d-glucoside and water.
From these
results it has been possible to draw conclusions about the surfactant
aggregation behavior at dilute
concentrations and when the n-octyl
β-d-glucoside concentration is increased. The water
diffusion in the
n-octyl β-d-glucoside/water system has been
compared with the diffusion process of water in a glucose
solution, and it has been possible to interpret the data in terms of
water diffusion in a glucose solution
with some additional obstruction effects from the micellar hydrocarbon
cores. The liquid crystalline phases
have been examined by means of small-angle X-ray scattering and
analyzed in terms of repetition distances
and area/head group in the hexagonal, cubic, and lamellar phases.
An important result of this study is
the fact that the area per glucose unit in the surfactant is an almost
invariant quantity across the phase
diagram.
“…The extension of the different phases occurring in AG/water systems displays a rather weaker temperature dependence than do EO-based surfactants. As expected for a nonionic surfactant, solutions of AGs in water are insensitive toward the addition of salt. − There are several indications − that it is the complex isomerism of the carbohydrate head group that determines the physicochemical properties of AGs. 1 α- and β- d -glucose and model structures indicating how a hydrocarbon chain will be attached to the glucose molecule in the two cases. In α- d -glucose (left), the hydrocarbon chain is attached to the axial hydroxyl group (marked with an arrow) at carbon number one.…”
The n-octyl
β-d-glucoside/water binary phase diagram (temperature vs
concentration) and the aggregation
parameters of the individual phases have been determined.
n-Octyl β-d-glucoside forms four
different
phases together with water. At temperatures below 22 °C, there
is an isotropic solution region from neat
water extending up to almost 60 wt % n-octyl
β-d-glucoside. As the concentration is further
increased,
three liquid crystalline phases form in the following order:
hexagonal, cubic, and lamellar. At high surfactant
concentrations (>93 wt %) the lamellar phase is in equilibrium with
hydrated crystals. The hexagonal
phase disappears at temperatures slightly higher than 20 °C. The
solution region has been investigated
with 1H-NMR to deduce the self-diffusion coefficients of
both n-octyl β-d-glucoside and water.
From these
results it has been possible to draw conclusions about the surfactant
aggregation behavior at dilute
concentrations and when the n-octyl
β-d-glucoside concentration is increased. The water
diffusion in the
n-octyl β-d-glucoside/water system has been
compared with the diffusion process of water in a glucose
solution, and it has been possible to interpret the data in terms of
water diffusion in a glucose solution
with some additional obstruction effects from the micellar hydrocarbon
cores. The liquid crystalline phases
have been examined by means of small-angle X-ray scattering and
analyzed in terms of repetition distances
and area/head group in the hexagonal, cubic, and lamellar phases.
An important result of this study is
the fact that the area per glucose unit in the surfactant is an almost
invariant quantity across the phase
diagram.
“…13 To study the role of surface tension forces in so elastic materials, we investigate the elastic behaviour of dispersions of bubbles in concentrated emulsions. Those aerated emulsions, which have applications in the food 14 and cosmetic 15 industries, have been the subject of rheological and stability studies. [16][17][18] However, their overall elastic properties have not yet been studied in detail.…”
We study the elastic properties of soft solids containing air bubbles. Contrary to standard porous materials, the softness of the matrix allows for a coupling of the matrix elasticity to surface tension forces acting on the bubble surface. Thanks to appropriate experiments on model systems, we demonstrate how the elastic response of the soft porous solid is governed by two dimensionless parameters: the gas volume fraction and a capillary number comparing the elasticity of the matrix with the stiffness of the bubbles. Furthermore, we show that our experimental results are accurately predicted by computations of the shear modulus through a micro-mechanical approach.
“…During recent years, the use of alkylglycosides has increased due to their good dermatological compatibility and biodegradability . They are now produced industrially in large scale from renewable raw material .…”
The mixing behavior of binary mixtures of the pure alkylglycosides: β-decylglucoside (β-C10G),
β-dodecylglucoside (β-C12G), β-decylmaltoside (β-C10M), and dodecylmaltoside (C12M) in combination with
different common surfactants has been studied. First, the effect of the nonionic polar headgroup and chain
length of the glycosidic surfactants in the mixed micellization with sodium dodecyl sulfate (SDS) was
investigated. Further on, to analyze the effect of the ionic headgroup on the micellization of the glycosidic
surfactant, β-C10G was mixed with different surfactants: dodecyltrimethylammonium bromide (DTAB),
dodecylheptaethylene glycol ether (C12E7), and β-C10M. All the mixed systems under study adapt reasonably
well to the model developed by Rubingh, with negative values for the interaction parameter, βm, indicating
a favorable interaction between the mixed surfactants. In the mixtures with SDS and the glycosides, the
interactions become stronger when the hydrocarbon chain length of the surfactant is shorter and the
hydrophilic headgroup is larger, i.e., when the surfactants become more hydrophilic. The β-C10G mixes
favorably with the other surfactants, the interaction becoming stronger in the order C12E7, β-C10M, SDS,
DTAB. The strong interaction in micellization with DTAB is explained by assuming an anionic character
in the β-C10G molecule, as shown by electroosmosis measurements. Finally, the favorable interaction with
β-C10M is explained by considering the packing between the headgroups of both nonionic surfactants.
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