Abstract:International audienceWe have studied single curved films stabilized by globular proteins, using small angle scattering. By combining both the use of in-house X-ray and synchrotron radiation, we have measured the structural properties of films (thickness, electronic density) by controlling the physicochemical properties of protein (ovalbumin, pH 7, bulk concentration 10 g L−1). For each experiment, solutions of highly purified protein were freshly prepared to eliminate any problem of aging. The observation of … Show more
“…Recently, this phenomenon has been evidenced in protein lamellae using X-ray scattering. 36 The fact that the lamella drainage is not described by a stepwise thinning suggests the formation of a unique lamellar liquid crystal-like brittle organization under confinement. Since the swollen lamella breaks when it stops, the structure must be preserved.…”
International audienceWe study the dynamics of a foam lamella in a confined channel under the influence of a pushing-pulling pressure. Using optical interferometry we evidence an instantaneous swelling described by a velocity power law for different compositions of the foaming solutions. Based on theoretical considerations we show that the phenomena are mainly dominated by surface forces which also contribute to the kinetics of the drainage. Moreover, the frictional force acting on the lamella during motion depends on the velocity leading to two separate sliding regimes
“…Recently, this phenomenon has been evidenced in protein lamellae using X-ray scattering. 36 The fact that the lamella drainage is not described by a stepwise thinning suggests the formation of a unique lamellar liquid crystal-like brittle organization under confinement. Since the swollen lamella breaks when it stops, the structure must be preserved.…”
International audienceWe study the dynamics of a foam lamella in a confined channel under the influence of a pushing-pulling pressure. Using optical interferometry we evidence an instantaneous swelling described by a velocity power law for different compositions of the foaming solutions. Based on theoretical considerations we show that the phenomena are mainly dominated by surface forces which also contribute to the kinetics of the drainage. Moreover, the frictional force acting on the lamella during motion depends on the velocity leading to two separate sliding regimes
“…Using synchrotron radiation X-ray scattering, it is now possible to highlight the molecular structure of a thin liquid film [21]. By X-ray diffraction no Bragg peak was observed in the spectra for thin liquid films containing SDS or SDS+glucose mixtures.…”
Section: Optical Activity and Raman Spectramentioning
We report on enhanced experimental optical activity measurements of thin soap films in the presence of sugar. This unusual optical activity is linked to the intramolecular chiral conformation of the glucose molecules at the air/liquid interface. Choosing sodium dodecylsulfate (SDS) as a model surfactant and glucose as model sugar, favorable interactions between the anionic group -OSO3(-)- and the glucose molecules are highlighted. This induces an interfacial anchoring of glucose molecules leading to a perturbing influence of the asymmetric chiral environment.
“…We have obtained a specular reflectivity profile in the shape of oscillations superimposed with a q À4 decay, the so-called Kiessig fringes. Experiments performed on a single film inside an ordered foam (a series of equidistant films in a Kapton tube) give information about the structural organization [17,18]. With a small amount of solution (20 ll for each measurement), it was difficult to stabilize film stack.…”
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