Acceleration of membrane dynamics adjacent to a wall

Abstract

The dynamics of an induced lamellar microemulsion adjacent to a planar hydrophilic surface (45 ns) were found to be three times faster compared to the bicontinuous bulk structure (133 ns). For these investigations the grazing incidence technique for neutron spin echo spectroscopy has been developed to resolve the depth dependent near surface dynamics. The observation is rationalized in terms of membrane hydrodynamics, where the flow fields reflected by the surface lead to a crossover from classical to confined fluctuations, and faster dynamics on large length scales (also known as "lubrication") are predicted.

Microemulsions as model fluids for enhanced oil recovery: dynamics adjacent to planar hydrophilic walls

“…In [6] we stated the interesting dynamical behavior we found for an induced lamellar microemulsion adjacent to a planar hydrophilic surface namely that the induced layer (45ns) is three times faster when compared with the bicontinuous bulk structure (133ns) (see Figure 1). In addition to our conference contributions we want the present complementary experiments we conducted in order the better the understanding of what leads to this behavior.…”

“…The main result of these GINSES experiments is summarized in Figure 1 [6]. While at low penetration depths we highlighted the near surface lamellar structure of the microemulsion.…”

Grazing incidence neutron spin echo spectroscopy: instrumentation aspects and scientific opportunities

“…Figure 1 shows a bicontinuous microemulsion measured in GISANS geometry. The interface imposes a lamellar phase for the first membrane layers, giving rise to a Bragg peak in the detector image, while the bulk microemulsion at larger distances to the interface contributes with a Debye-Scherrer like scattering contribution [4]. The typical Q-value for a GINSES experiments is indicated with the red circle in the GISANS plot (on the Q y =0 axis).…”

“…The scattered neutrons from the evanescent wave are recorded to get structural information lateral and perpendicular to the rigid interface on a nanometer length scale. Recently, this technique has been also applied to study the dynamics of mesoscopic objects close to the rigid interface [4][5] [8] with Neutron Spin Echo (NSE) spectroscopy. NSE spectroscopy has the highest energy resolution of all spectroscopic techniques [6] [7] in neutron scattering and allows to study the dynamics of macromolecules such as thermal fluctuations of surfactant membranes [9][10] or internal motion of proteins [3].…”

“…A very high instrumental stability (stable currents, no thermal effects at the coils) and a low magnetic and radiation background of the surrounding is mandatory for such GINSES experiments. The GINSES technique has been applied to microemulsions [4][5] [12] and microgels [11] near interfaces. As an example, the dynamics of a lamellar microemulsion, consisting of d-decane and D 2 O to equal amounts, and 32% of the surfactant C 10 E 4 4, and the influence of the scattering vector is presented ( Figure 2).…”