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Krafft M.P.,Charles Sadron Institute | Fainerman V.B.,Donetsk Medical University | Miller R.,MPI of Colloids and Interfaces
Colloid and Polymer Science | Year: 2015

An equation of state for insoluble monolayers was applied to describe the isotherms of phospholipids measured in presence of a fluorocarbon in the gas phase. The observed co-adsorption mechanism of dipalmitoylphosphatidylcholine (DPPC) and the fluorocarbon molecules manifests itself in remarkable differences of the cohesion surface pressure Πcoh. Due to the interaction of the adsorbed fluorocarbon molecules with DPPC, the mutual interaction energy between DPPC molecules is reduced, leading to a very effective fluidization of the monolayer. Equilibrium and dynamic surface tension data taken from literature for phospholipids adsorbed from an aqueous solution or dispersion, in absence and presence of perfluorohexane (PFH) in the adjacent vapor phase, have been analyzed by the proposed theory. It was found that the adsorption equilibrium constant for dioctanoylphosphatidylcholine (di-C8PC) is increased in the presence of PFH and the intermolecular interaction between the components is strong. The dynamic surface tensions of the given systems are described by a diffusion-controlled adsorption mechanism. © 2015 Springer-Verlag Berlin Heidelberg Source

Gaponik N.,TU Dresden | Shchukin D.G.,MPI of Colloids and Interfaces | Sviridov D.V.,Belarussian State University
Zeitschrift fur Physikalische Chemie | Year: 2011

A facile method of patterning of various dielectric substrates (glass, quartz, and polyimide) with thin films of conducting polyaniline with at least 10 μm resolution is demonstrated. This method can be applied for the fabrication of functional conducting polymer interconnections between microelectrode arrays separated by dielectric gaps. Such interconnections may find applications in microelectrochemical sensors and electrocatalytic systems. © by Oldenbourg Wissenschaftsverlag, München. Source

Mys V.D.,Donetsk Medical University | Fainerman V.B.,Donetsk Medical University | Makievski A.V.,SINTERFACE Technologies | Krafft M.P.,Charles Sadron Institute | Miller R.,MPI of Colloids and Interfaces
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2015

The dynamic surface tension of aqueous solutions of C10EO8 at the interfaces with air and saturated hexane vapor was measured by the maximum bubble pressure tensiometer BPA for adsorption times t≥0.01s. It can be shown that the dynamic surface pressure of C10EO8 solutions in a saturated hexane atmosphere increases at short adsorption times with increasing surfactant concentration. The theory of diffusion controlled adsorption of two surfactants from the water and gas phases, respectively, was used for data analysis. The obtained experimental results agree with a model based on a reorientation of the C10EO8 molecules, assuming a strong intermolecular interaction between hexane and C10EO8 molecules in the surface layer. Alternatively, an additional enhancement of C10EO8 adsorption activity can be assumed due to the presence of hexane molecules at the interface. © 2015 Elsevier B.V. Source

Liggieri L.,CNR Institute of Neuroscience | Miller R.,MPI of Colloids and Interfaces
Current Opinion in Colloid and Interface Science | Year: 2010

The relaxation behaviour of surfactant layers provides a deep insight into the composition and structure of adsorbed layers at liquid interfaces. The development of professional experimental tools created a helpful basis for an increasing interest in these studies. In addition, the theoretical basis has been improved in many aspects such that for several surfactant systems a quantitative understanding is already possible. In particular the consideration of the changes in molar area of adsorbed molecules, introduced into the thermodynamics of adsorbed layers first by Fainerman in 1995, due to changes in the surface coverage allowed a considerably better, in many cases even quantitative understanding of the surface relaxation. Another important additional property, introduced into the thermodynamics and consequently also into the mechanisms of relaxation processes in interfacial layers, is the two-dimensional compressibility, important for the response to deformations of rather packed interfacial layers. The experimentally observed negative dilational viscosity is discussed only briefly and considered essentially in terms of experimental and theoretical shortcomings. The relaxation behaviour of nano- and microparticles, in literature often addressed is compounds able to act "instead of surfactants" are also addressed and some peculiarities discussed, while the obvious interrelation between the dilational rheology and stability of foams and emulsions is not analysed in detail. © 2010 Elsevier Ltd. Source

Werner P.,MPI of Microstructure Physics | Blumtritt H.,MPI of Microstructure Physics | Zlotnikov I.,MPI of Colloids and Interfaces | Graff A.,Fraunhofer Institute for Mechanics of Materials | And 2 more authors.
Journal of Structural Biology | Year: 2015

We report on a structural analysis of several basal spicules of the deep-sea silica sponge Monorhaphis chuni by electron microscope techniques supported by a precise focused ion beam (FIB) target preparation. To get a deeper understanding of the spicules length growth, we concentrated our investigation onto the apical segments of two selected spicules with apparently different growth states and studied in detail permanent and temporary growth structures in the central compact silica axial cylinder (AC) as well as the structure of the organic axial filament (AF) in its center. The new findings concern the following morphology features: (i) at the tip we could identify thin silica layers, which overgrow as a tongue-like feature the front face of the AC and completely fuse during the subsequent growth state. This basically differs from the radial growth of the surrounding lamellar zone of the spicules made of alternating silica lamellae and organic interlayers. (ii) A newly detected disturbed cylindrical zone in the central region of the AC (diameter about 30. μm) contains vertical and horizontal cavities, channels and agglomerates, which can be interpreted as permanent leftover of a formerly open axial channel, later filled by silica. (iii) The AF consists of a three-dimensional crystal-like arrangement of organic molecules and amorphous silica surrounding these molecules. Similar to an inorganic crystal, this encased protein crystal is typified by crystallographic directions, lattice planes and surface steps. The 〈0. 0. 1〉 growth direction is especially favored, thereby scaffolding the axial cylinders growth and consequently the spicules' morphology. © 2015 Elsevier Inc. Source

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