TY - JOUR A1 - Penacorada, Florencio A1 - Souto, Jorge A1 - de Saja, J. A. A1 - Brehmer, Ludwig T1 - Brewster angle microscopy and surface potential measurements of Langmuir-Blodgett films of zinc tri(tert-butyl)- 4-sulphophthalocyanine N2 - The formation of a Langmuir monolayer of an amphiphilic derivative of zinc phthalocyanine (Na[(ZnPcSO3)-S-t]) has been studied by means of surface potential technique and Brewster angle microscopy. The experiments were undertaken in order to understand the behaviour of this monolayer with a well-defined surface pressure isotherm. The floating film is described as a truly monomolecular layer formed by very rigid islands in which the phthalocyanine units tend to take on a preferential orientation with their planes perpendicular to the air-water interface, for high values of the surface pressure. (c) 2004 Elsevier B.V. All rights reserved Y1 - 2005 SN - 0169-4332 ER - TY - JOUR A1 - Knochenhauer, Gerald A1 - Penacorada, Florencio A1 - Reiche, Jürgen A1 - Brehmer, Ludwig A1 - Tredgold, Richard H. A1 - Barberka, Thomas Andreas T1 - Multilayers of perfluorinated fatty acids N2 - We have formed Y layers of perfluorododecanoic acid CF3(CF2)10COOH by thermal evaporation in vacuo and of perfluorotetradecanoic acid CF3(CF2)12COOH by thermal evaporation and by the Langmuir-Blodgett (LB) technique. We have obtained the bilayer spacing of both these materials by X-ray diffraction and have also studied the in-plane structure of these materials by means of grazing incidence diffraction (GID). Computer modelling was used to interpret the results obtained. For the perfluorododecanoic acid, we find two stable untwisted phases at 25°C and a combination of these two predicts both the Bragg peaks arising from the layer structure and the GID results. Our experimental results show that the perfluorotetradecanoic acid exists in the generally accepted helical structure. Computer modelling leads to the conclusion that closely packed perfluorinated chains with 12 or less carbon atoms should exist in an untwisted state while molecules having more than 12 carbon atoms show the onset of the helical conformation. Y1 - 1999 ER - TY - JOUR A1 - Englisch, Uwe A1 - Penacorada, Florencio A1 - Brehmer, Ludwig A1 - Pietsch, Ullrich T1 - X-ray and neutron reflection analysis of the structure and the molecular exchange process in simple and complex fatty acid salt Langmuir-Blodgett multilayers Y1 - 1999 ER - TY - JOUR A1 - Englisch, Uwe A1 - Katholy, Stefan A1 - Penacorada, Florencio A1 - Reiche, Jürgen A1 - Pietsch, Ullrich T1 - Investigation of molecular diffusion across organic multilayers using neutron specular reflectivity Y1 - 1999 ER - TY - JOUR A1 - Englisch, Uwe A1 - Penacorada, Florencio A1 - Samoilenko, I. A1 - Pietsch, Ullrich T1 - Investigation of the vertical molecular exchange in a complex organic multilayer system Y1 - 1998 ER - TY - JOUR A1 - Bolm, A. A1 - Englisch, Uwe A1 - Penacorada, Florencio A1 - Gerstenberger, M. A1 - Pietsch, Ullrich T1 - Temperature and time dependent investigations of cd- and uranyl-stearate multilayers by means of neutron reflectivity measurements Y1 - 1997 ER - TY - JOUR A1 - Souto, Jorge A1 - Rodriguez-Mendez, Maria-Luisa A1 - Penacorada, Florencio A1 - Reiche, Jürgen T1 - Small angle x-ray reflectivity study of Langmuir-Blodgett films of a peripherally substituted zinc phthalocyanine N2 - Langmuir-Blodgett films of zinc 11,18,25-tri(tert-butyl)-4-sulfo-phthalocyanine (ZNPctSO3Na) have been deposited onto hydrophilic and hydrophobic silicon wafers. Y-type films were formed on both types of substrate, and the transfer ratio was very close to unity. The organization of the films on the molecular level was probed by X-ray specular reflectivity. Y1 - 1997 ER - TY - JOUR A1 - Reiche, Jürgen A1 - Penacorada, Florencio A1 - Geue, Thomas A1 - Pietsch, Ullrich A1 - Brehmer, Ludwig T1 - Monolayers and multilayers of uranyl arachidate : in-plane structure of uranyl arachidate multilayers N2 - The molecular in-plane structure of uranyl arachidate Langmuir-Blodgett (LB) films formed at different subphase pH values was analysed by means of X-ray grazing-incidence diffraction. For multilayers formed at low subphase pH a reorganisation of the arachidic acid film structure is confirmed. At appropriate subphase pH values, reorganisation of the film structure, e.g. via the formation of three-dimensional crystallites, is prevented by the presence of the uranyl ions and by the subsequent introduction of conformational disorder (gauche defects) in the alkyl chains. The observation of a macroscopic flow-induced in-plane texture in these uranyl arachidate LB films has profound implications for the design of ordered, supramolecular structures by the Langmuir-Blodgett technique. Y1 - 1997 ER - TY - JOUR A1 - Penacorada, Florencio A1 - Reiche, Jürgen A1 - Zetzsche, Thomas A1 - Dietel, Reinhard A1 - Brehmer, Ludwig A1 - Saja, Jose-Antonio de T1 - Stabilisation of fatty acid mono- and multilayers by simultaneous polyelectrolyte complexation and salt formation with cadmium ions N2 - The complexation of highly ordered fatty acid monolayers with polyelectrolytes is expected to yield well- ordered Langmuir films suitable for the formation of Langmuir-Blodgett multilayers with improved long-term stability. Studies of the surface pressure-area isotherms and of the surface potential kinetics yield detailed information regarding the influence of these polymeric counterions on the monolayer properties. The injection of bivalent metal salts into the subphase after the complexation was used to improve the order and stability of the mono- and multilayers. The corresponding Langmuir-Blodgett films were investigated by means of X-ray reflectivity measurements and scanning force microscopy. The polyion complex multilayers show a strongly increased mechanical stability compared with films of fatty acid salts formed with bivalent metal ions. These structures are expected to be suitable as ultrathin separation layer for gas separation or ultrafiltration membranes. Y1 - 1997 ER - TY - JOUR A1 - Papra, Alex A1 - Penacorada, Florencio A1 - Reiche, Jürgen A1 - Katholy, Stefan A1 - Brehmer, Ludwig A1 - Hicke, Hans-Georg T1 - Structure and Stability of Langmuir Monolayers and Langmuir-Blodgett Films of Bisaroyl Azide Bolaamphiphiles N2 - Langmuir-Blodgett films of bolaamphiphiles with reactive head groups can be used for the surface modification of composite membranes for gas separation processes. The scope of our investigations was to get a detailed insight in the monolayer behaviour and LB film structure of previously synthesized bisaroyl azide bolaamphiphiles. The layers have been analyses by means of surface potential measurements and Brewster angle microscopy. Furthermore parameters for a successful LB Film deposition were found. As expected for a molecule with two hydrophilic ends the transfer ratio on upstroke was close to one and on downstroke no transfer occurred. The multilayer structure was analysed by scanning force microscopy and X-ray reflectivity measurements. The SFM images revealed a periodic in plane structure on molecular level. Based on a combination of the X-ray data with results of other methods two possible models of the multilayer structure are presented Y1 - 1997 ER -