TY  - JOUR
A1  - Koetz, Joachim
A1  - Brühl, Iris
A1  - Kosmella, Sabine
A1  - Reiche, Jürgen
A1  - Tiersch, Brigitte
T1  - Polyelectrolyte Complex Formation in Lamellar Liquid Crystalline Systems
N2  - The influence of polyelectrolytes on structure formation in liquid crystalline Na-dodecylsulfate/decanol/water systems was investigated by means of small angle X-ray diffraction, rheology, NMR spectroscopy, and microscopy. By adding Na-polyacrylate (PAA) into the mesophase, the one-phase region is left and phenomena of phase separation into a solvent-rich and a polymer/surfactantrich phase occurs. By incoporating an anionic and cationic polyelectrolyte step by step the tendency of phase separation is increased drastically. The self-organization process can be regulated directly by varying the water content of the system. However, at a water content of 30% the properties of the resulting liquid crystal were changed drastically. X-ray diffraction shows a multitude of Bragg peaks, NMR shows a peak-splitting, and rheology shows a change from non-Newtonian to Newtonian-flow behavior. On the basis of the experimental results an ordered multilayer associate structure can be assumed.
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Hofmann, Dieter
A1  - Reiche, Jürgen
T1  - Molecular organization of amphiphilic disc-shaped penta-alkynes in LB-mono- and multilayers
N2  - Amphiphilic disc-shaped penta-alkynes were studied with regard to their molecular organization in Langmuir-Blod- gett (LB) mono- and multilayers. It was found that each compound investigated forms edge-on arranged stable monolayers at the air-water interface. LB-multilayers derived from fivefold pentyl-substituted pentaynes are characterized by an edge-on ordering of the molecules within Y-type bilayers. One of these compounds, containing a hydoxy substituent as hydrophilic head group, is exemplified and two possible rectangular molecular assemblies perpendicular to the substrate, each with a columnar in-plane packing, will be discussed as a result of molecular modelling. Based on the experimental results, hexagonal layer packing in the LB-film of a disc-shaped penta-alkynyl carboxylic acid without lateral substituents proved to be possible, which, furthermore, could be confirmed by molecular mechanics simulation.
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Knochenhauer, Gerald
T1  - Numerische Simulation und Röntgenbeugung an thermisch aufgedampften Multischichten perfluorierter Fettsäuren
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Dietel, Reinhard
A1  - Lemmetyinen, Helge
A1  - Janietz, Dietmar
A1  - Lemmetyinen, Helge
A1  - Brehmer, Ludwig
T1  - Edge-on Langmuir-Blodgett multilayers derived from disc-shaped multiyne mesogens
N2  - Langmuir-Blodgett(LB) multilayers were prepared from disc-shaped multiyne mesogens based on amphiphilic alkyl pentakis(aryl-ethynyl)benzene ethers. The two compounds used are characterized by five hydrophobic flexible chains and one hydrophilic substituent at the terminal position of the alkoxy chain. The LB films were analysed by X-ray scattering and spectroscopic measurements. An edge-on arrangement of the two discotic pentaalkynes within Y-type bilayers with a different packing density proved to be possible for the LB films of both compounds.
Y1  - 1992
ER  - 
TY  - JOUR
A1  - Peñacorada, Florencio
A1  - Souto, Jorge
A1  - Katholy, Stefan
A1  - Saja, José-Antonio de
A1  - Reiche, Jürgen
T1  - Structure of Langmuir monolayers of substituted phthalocyanines
N2  - Langmuir floating layers of two phthalocyanine derivatives, ytterbium bisphthalocyanine and tetra-tert-butyl nickel phthalocyanine, were investigated by means of compression isotherms, surface potential kinetics and Brewster angle microscopy (BAM) in order to study the influence of peripheral substituents on the structure and stability of these films and on their suitability for a subsequent transfer onto solid substrates. Specific substitutions that may lead to amphiphilic molecular units seem to play a key role in the development of well organised thin films prepared with this technique.
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Zetzsche, Thomas
A1  - Helms, Andreas
A1  - Freydank, Anke-Christine
A1  - Knochenhauer, Gerald
A1  - Schulz, Burkhard
A1  - Brehmer, Ludwig
T1  - Organized molecular films of oxadiazole compounds formed by vacuum deposition
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Wüstneck, Rainer
A1  - Reiche, Jürgen
A1  - Förster, Stephan
T1  - Surface dilational behavior of docosanic acid monolayers spread on the surface of drops of polymer solutions
N2  - The pendant drop technique was used to determine p/A isotherms of docosanic acid spread on the drop surface of an aqueous polymer solution. Two water soluble polymers were used, poly(dimethyl-diallyl-ammoniumchloride) and sodium poly(styrene sulfonate-b-ethylethylene). By fast changes of the drop volume, the monolayers were compressed and dilated. The stress relaxation was monitored and surface rheological dilation parameters were obtained. It is shown that the fatty acid monolayer can be mechanically stabilized by both interacting anionic and cationic polymers. In the case of the anionic polymer, the interaction becomes more pronounced in the presence of salts in the subphase (counterions). Brewster angle microscopy shows that the typical tilt-orientation of crystalline domains of the fatty acid monolayers transforms into a more uniform and fluid-like structure caused by the polymer/monolayer interaction. The surface rheological behavior is dramatically influenced by the polymer binding. The interaction results in surface dilational viscoelastic properties and show that there is a strong resistance against expansion of the complex fatty acid/polymer layer.
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Penacorada, Florencio
A1  - Angelova, Angelina
A1  - Kamusewitz, Helmut
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
T1  - Scanning Force Microscopy and Wetting study of the Surface Modification of a Polypropylene Mambrane by Means of Langmuir-Blodgett Film Deposition
N2  - Polypropylene membranes with deposited ultrathin "siin" layers are attractive for separation and cleaning of gaseous mixtures. In the present study, the surface morphology and wetting hysteresis of composite membranes consisting of a microporous polypropylene support and Langmuir-Blodgett ("skin") films, are investigated. The effect of the interlayer molecular interactions and the substrate features on the integrity and homogeneity of the "skin" layers is examined. Langmuir-Blodgett films of arachidic acid and cadmium and calcium arachidate are characterized both on smooth silicon and on porous polypropylene supports. Contact angle measurements and scanning force microscopy (SFM) are applied for investigations of the membrane surface modification upon transfer of a different number of monolayers. It was found that the contact angle hysteresis of the bare membrane decreases after the LB-deposition of close-packed monolayers. Smoothing of the membrane surface is also evidenced by the SFM images, on different length scales, confirming a good coverage of the membrane pores.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Janietz, Dietmar
A1  - Barberka, Thomas Andreas
A1  - Hofmann, Dieter
A1  - Brehmer, Ludwig
T1  - Comprehensive structure investigation of Langmuir-Blodgett films of disc-shaped molecules
N2  - The structure of mono- and multilayers of amphiphilic disc-shaped pentaynes wa inbestigated by Brewsterangle microscopy, X-ray specular reflection and grazing incidence diffraction (GID). X-ray specular reflection experiments confirm the "edge on" arrangement of the molecular discs. The molecular modelling of the Langmuir-Blodgett (LB)- multilayers predicts a columnar in-plane packing of the molecules. A GID experiment with monochromatic synchrotron radiation was used to verify the predicted multilayer structure on molecular level, while the Brewsterangle microscopy gave a deeper insight in the monolayer in-plane structure on micron scale.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Penacorada, Florencio
A1  - Reiche, Jürgen
A1  - Katholy, Stefan
A1  - Brehmer, Ludwig
A1  - Rodriguez-Mendez, Maria-Luisa
T1  - Monolayers and multilayers of uranyl arachidate : 1. study of the interaction of dissolved uranyl ions with arachidic acid Langmuir monolayers
N2  - Langmuir monolayers of arachidic acid have been prepared on a subphase containing uranyl ions (O-U-O)ý+. The interaction between the uranyl ions and the monolayer of arachidic acid has been studied by means of surface pressure and surface potential isotherms and Brewster angle microscopy at different pH values (ranging from 1.5 to 8). A similar systematic study has been carried out in the presence of Cdý+ ions for comparison purposes. The surface pressure and surface potential isotherms demonstrate that the acid to salt conversion of arachidic acid in the presence of uranyl ions occurs at lower bulk pH values (pH=3.5) as compared with other bivalent metal counterions such as Cdý+. Changes in the surface morphology of the monolayer induced by the interaction with uranyl- and cadmium ions are analyzed and the correlation between the surface potential change and the morphology of the films is discussed.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Freydank, A.
A1  - Dietzel, Birgit
A1  - Katholy, Stefan
A1  - Knochenhauer, Gerald
A1  - Zetzsche, Thomas
A1  - Schulz, Burkhard
A1  - Brehmer, Ludwig
T1  - Komplexe Strukturanalytik von Oxadiazol-Mono- und Multischichten
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Penacorada, Florencio
A1  - Geue, Thomas
A1  - Pietsch, Ullrich
A1  - Brehmer, Ludwig
T1  - In-plane structure of uranylarachidate multilayers
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Brehmer, Ludwig
A1  - Dietzel, Birgit
A1  - Freydank, Anke-Christine
A1  - Katholy, Stefan
A1  - Knochenhauer, Gerald
A1  - Reiche, Jürgen
A1  - Schulz, Burkhard
A1  - Zetzsche, Thomas
T1  - Langmuir- und Langmuir-Blodgett-Filme amphiphiler Oxadiazole
Y1  - 1995
ER  - 
TY  - THES
A1  - Reiche, Jürgen
T1  - Beiträge zur Strukturaufklärung organischer Mono- und Multischichten
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Geue, Thomas
A1  - Katholy, Stefan
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
A1  - Caliebe, W.
T1  - Grazing incidence x-ray diffraction (GIXD) measurements of uranyl arachidate (UO2A2) LB films
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
T1  - Antiphase domains in Langmuir-Blodgett films
N2  - For bilayer stacks of non-centrosymmetrical molecules, formed by the Langmuir-Blodgett (LB) technique (Y deposition), 00l peaks for the bilayer period are usually observed in the X-ray specular reflectivity curve, in this study, we show that the introduction of stacking disorder at lower transfer ratios and the subsequent partial repair of defects by a parallel shift of oppositely oriented molecules into the vacancies may result in the formation of antiphase domains and in an increase in the average monolayer symmetry followed by quenching of the bilayer peaks. The X-ray reflectivity data, obtained for multilayers of penta-alkynes, are used to demonstrate this real structural effect, which is expected to be of general importance for X-ray and neutron reflectivity data reduction and for the structural modelling of multilayers.
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Knochenhauer, Gerald
A1  - Barberka, Thomas Andreas
A1  - Geue, Thomas
A1  - Pietsch, Ullrich
A1  - Brehmer, Ludwig
A1  - Hodge, P.
A1  - Tredgold, Richard H.
T1  - In-plane structure of perfluorotetra decanoic acid Langmuir-Blodgett films and films formed by vacuum deposition
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Dietzel, Birgit
A1  - Freydank, Anke-Christine
A1  - Geue, Thomas
A1  - Pietsch, Ullrich
A1  - Brehmer, Ludwig
T1  - Lateral structure of thermally treated oxadiazole Langmuir-Blodgett films
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Penacorada, Florencio
A1  - Zetzsche, Thomas
A1  - Katholy, Stefan
A1  - Brehmer, Ludwig
T1  - Polyelektrolyt-Fettsäure-Multiphasen-LB-Schichten
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Englisch, Uwe
A1  - Barberka, Thomas Andreas
A1  - Pietsch, Ullrich
A1  - Höhne, U.
A1  - Reiche, Jürgen
A1  - Dietzel, Birgit
T1  - Neutronenreflektivität an Langmuir-Blodgett-Strukturen
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Jutila, Arimati
A1  - Janietz, Dietmar
A1  - Reiche, Jürgen
A1  - Lemmetyinen, Helge
T1  - Photophysical investigation of Langmuir-Blodgett films of amphiphilic discotic penta-alkynes
N2  - Amphiphilic discotic pentakis (arylethynyl) benzene compounds 1 and 2 containing an enlarged aromatic core functioning as a chromophoric p-electron system were studied with regard to their photophysical properties within Langmuir-Blodgett (LB) films. The results obtained from steady-state absorption as well as fluorescence excitation and emission measurements will be discussed with regard to interchromophoric interactions in the LB films. Time-resolved fluorescence inves6igations revealed the formation of a ground-state complex as well as excimer formation. Thermal treatment causes irreversible destruction of the LB film structure of the discotic amphiphiles. Within droplets the reorganization of the original nematic-discotic (ND) mesophase of the bulk materials was found for the alcohol 2 as indicated by a Maltese Cross texture, whereas the acid 1 remained isotopic.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Knochenhauer, Gerald
A1  - Reiche, Jürgen
A1  - Barberka, Thomas Andreas
A1  - Woolley, Martin
A1  - Tredgold, Richard H.
A1  - Hodge, P.
A1  - Brehmer, Ludwig
T1  - Do perfluorianted chains always have to be twisted?
N2  - Short perfluorinated cabon chains do not take on helical structure when they are closely packed
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Dietzel, Birgit
A1  - Freydank, A.
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
A1  - Knoblauch, H.
A1  - Knochenhauer, Gerald
A1  - Zetzsche, Thomas
T1  - Mono- und Multischichten von neuen aromatischen 1,3,4-Oxadiazolen
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Penacorada, Florencio
A1  - Dietel, Reinhard
A1  - Reiche, Jürgen
A1  - Zetzsche, Thomas
A1  - Knobloch, Harald
A1  - Katholy, Stefan
A1  - Brehmer, Ludwig
T1  - Studium des Einflusses von Uranyl-Gegenionen auf die Struktur von Langmuir- und Langmuir-Blodgett Filmen der Arachinsäure
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Katholy, Stefan
A1  - Reiche, Jürgen
A1  - Dietzel, Birgit
A1  - Ruhmann, Ralf
A1  - Prescher, Dietrich
T1  - Copolymerer funktionalisierte Methacrylate
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Englisch, Uwe
A1  - Pietsch, Ullrich
A1  - Reiche, Jürgen
A1  - Dietzel, Birgit
T1  - Neutronenreflektivität von teildeuterierten LB-Filmen mit verschiedenen Verhältnissen on protonierten zu deuterierten Schichten
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Helms, Andreas
A1  - Reiche, Jürgen
A1  - Stiller, Burkhard
A1  - Kobloch, H.
A1  - Brehmer, Ludwig
T1  - Herstellung dünner organischer Schichten durch Vakuumdeposition
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
T1  - Antiphasen : Domänen in Langmuir-Blodgett Schichten
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Barberka, Thomas Andreas
A1  - Knochenhauer, Gerald
A1  - Woolley, Martin
A1  - Pietsch, Ullrich
T1  - Comprehensive structure investigation and computer modelling of perfluorododecanoic acid multilayers formed by in-vacuo thermal evaporation
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Barberka, Thomas Andreas
A1  - Janietz, Dietmar
A1  - Hofmann, Dieter
A1  - Pietsch, Ullrich
A1  - Brehmer, Ludwig
T1  - X-ray structure investigation and computer modelling of Langmuir-Blodgett films formed from disc-shaped pentaalkines
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Möbius, Dietmar
A1  - Festag, R.
A1  - Wendorff, Joachim Heinz
A1  - Ahuja, Rajeev C.
A1  - Reiche, Jürgen
T1  - Supramolecular organization of amphiphilic discotic mesogens
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Angelova, Angelina
A1  - Ionov, Radoslav
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
T1  - Head-to tail or head-to-head structure of Langmuir-Blodgett long chain ester multilayers?
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Pietsch, Ullrich
A1  - Fink, Hans-Peter
A1  - Lemmetyinen, Helge
T1  - A comparison fo x-ray methods for structure refinement of Langmuir-Blodgett multilayers
N2  - The possibilities and limits of structure refinement of Langmuir-Blodgett films by means of symmetrical reflection of X- rays are described using the example of a stearic acid multilayer. Three different techniques for the determiantion of the electron density profile from reflectivity data are compared; a Fourier method, a Patterson method, and model calculations. The important role of the a priori information for finding the besft structure model is outlined.
Y1  - 1992
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Hofmann, Dieter
A1  - Reiche, Jürgen
T1  - Reply to comment on "Molecular organization of amphiphilic disc-shaped penta-alkynes in LB mono- and multilayers"
N2  - The model for the Langmuir-Blodgett (LB) film structure of amphiphilic disc-shaped penta-alkynes is refined. It is shown that LB experiments reported in a comment on one of our papers do not contradict the molecular organization within the LB films of the penta-alkynes we proposed.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Kamusewitz, Helmut
A1  - Keller, Manuela
A1  - Brehmer, Ludwig
A1  - Peñacorada, Florencio
T1  - Study of gas transport through composite membranes with a stabilised Langmuir-Blodgett skin layer
N2  - The Langmuir-Blodgett (LB-) technique is used to deposit molecular reinforced separation layers on porous polymer substrates resulting in composite membranes for gas separation. The adsorption of a polycation to the arachidic acid Langmuir layer and the subsequent transfer of the highly ordered and stabilised monolayer onto a polypropylene membrane (Cellgard 2400) yields a laminated separation layer combining the advantageous high degree of order of fatty acid films and the stability of thin polymeric films. X-ray reflectivity data of these films confirm the transfer of the assembled polymer layer together with the fatty acid monolayer and the formation of ordered Y-type LB-films. SFM pictures show a dense film without pinholes completely covering the porous support. Gas permeation measurements are used to study the transport process of different gases through the composite membrane.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Angelova, Angelina
A1  - Reiche, Jürgen
A1  - Ionov, Radoslav
A1  - Janietz, Dietmar
A1  - Lemmetyinen, Helge
A1  - Brehmer, Ludwig
T1  - Control of the structure of Langmuir-Blodgett films of a discotic liquid crystalline compound via the subphase composition and the adjacent molecular environment
N2  - Changes of the molecular arrangenemt that can be induced by means of the LB technique in the multilayers of a disc-shaped multialkynyl amphiphile are monitored by means of small angle X-ray diffraction. Studies of the monolayers at the air-water interface reveal "edge-on" orientation of the discs. Specific effects of the counter- ions (Na+, Cd²+, Pb²+, and Ba²+) and sub-solution pH on the monolayer collapse pressure, transfer efficiency and molecular order in the multilayers are found. A correlation between the monolayer properties and the ability for formation of periodic discotic structures in the presence of divalent counterions is established. The discotic molecules retain their "edge-on" arrangement in the highly compressed transferred films with slight irregular interdigtation of the flexible wings and inclination to the substrate normal. The tilt and the inter- digitation are reduced when the discotic monolayers are deposited in alternating LB films with barium arachidate spacer layers.
Y1  - 1994
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  - Reiche, Jürgen
A1  - Knochenhauer, Gerald
A1  - Dietel, Reinhard
A1  - Freydank, Anke-Christine
A1  - Zetzsche, Thomas
A1  - Pietsch, Ullrich
A1  - Brehmer, Ludwig
A1  - Barberka, Thomas Andreas
A1  - Geue, Thomas
T1  - Structure of thermally treated oxadiazoleamide Langmuir-Blodgett films
N2  - The thermal treatment of Y-type Langmuir-Blodgett (LB) films formed from the amphiphilic derivative of 2,5- diphenyl-1,3,4-oxadiazole 1 results in changes of the molecular packing. These changes have been analysed by a combination of X-ray specular reflectivity data, X-ray grazing incidence diffraction data and scanning force microscopy images, On the basis of these experimental data we have simulated possible supramolecular structures, These simulations provide insight into the intermolecular interactions giving rise to the observed structural transitions. The crystalline structure induced by thermal treatment of the LB films is characterized by a uniaxial texture, which is correlated with the dipping direction during deposition of the LB film.
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  - Reiche, Jürgen
A1  - Schulz, Burkhard
A1  - Knochenhauer, Gerald
A1  - Dietzel, Birgit
A1  - Freydank, Anke-Christine
A1  - Zetzsche, Thomas
A1  - Brehmer, Ludwig
T1  - Supramolecular structures formed from heterocyclic aromatic molecules
N2  - This paper describes the formation and structure investigation of Langmuir monolayers and Langmuir-Blodgett multilayers formed from amphiphilic derivatives of 2,5-diphenyl-1,3,4-oxadiazole. The 2,5-diphenyl-1,3,4-oxadiazole group as a functional unit with interesting physical and chemical properties is maintained, while the head group, the length of the alkyl chain and the structure of the coupling unit between aromatic and aliphatic part of these linear short-chain amphiphiles is systematically varied in order to explore the influence of this change on the film forming properties and the stability of Langmuir and Langmuir-Blodgett films. Molecular mechanics simulations are shown by these systematic variations to be suitable for the prediction of optimal chemical structures allowing for a stable stratified molecular packing. The combination of a detailed structure investigation of the multilayers based on scanning force microscopy and X-ray data with molecular mechanics simulations yields an insight into the packing of the molecules and the intermolecular interactions.
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  - 
TY  - JOUR
A1  - Penacorada, Florencio
A1  - Reiche, Jürgen
A1  - Dietel, Reinhard
A1  - Zetzsche, Thomas
A1  - Stiller, Burkhard
A1  - Knobloch, Harald
A1  - Brehmer, Ludwig
T1  - Monolayers and multilayers of uranyl arachidate : 2. Influence of the subphase pH on the structure and stability of Langmuir-Blodgett films
N2  - In this second paper we describe the comprehensive structure investigations on multilayers of uranyl arachidate formed by Langmuir-Blodgett deposition from subphases of different pH on solid substrates by means of a combination of infrared spectroscopy, X-ray specular reflection, ellipsometry, and scanning force microscopy, The structure of these multilayers and their stability are obviously influenced by the subphase pH. The pH range of the acid to salt conversion determined for the Langmuir films is confirmed by the infrared spectroscopic data of the multilayers. While arachidic acid films, deposited from an uranyl acetate subphase of low pH, are found to have strongly distorted rough surface, the films of uranyl structure, The influence of the counterions on the alkyl chain conformation, chain packing, reorganization probability, and stability of the multilayer is discussed.
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
T1  - Einfluss des Transferverhältnisses auf die Monoschichtsymmetrie in Y-Typ Langmuir-Blodgett-Schichten
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Katholy, Stefan
T1  - Herstellung und Strukturaufklärung dünner organischer Schichten
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
T1  - Mono- und Multischichten aus Polyelektrolyt-Carbonsäure-Komplexen
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Katholy, Stefan
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
T1  - Strukturuntersuchungen an Langmuir-Monoschichten organischer Amphiphile mittels Brewsterwinkelmikroskopie
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
T1  - Antiphasen domains in Langmuir-Blodgett films
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Kratz, Karl
A1  - Hofmann, Dieter
A1  - Lendlein, Andreas
T1  - Current status of Langmuir monolayer degradation of polymeric biomaterials
JF  - The international journal of artificial organs
N2  - Langmuir monolayer degradation (LMD) experiments with polymers possessing outstanding biomedical application potential yield information regarding the kinetics of their hydrolytic or enzymatic chain scission under well-defined and adjustable degradation conditions. A brief review is given of LMD investigations, including the author's own work on 2-dimensional (2D) polymer systems, providing chain scission data, which are not disturbed by simultaneously occurring transport phenomena, such as water penetration into the sample or transport of scission fragments out of the sample.
 A knowledge-based approach for the description and simulation of polymer hydrolytic and enzymatic degradation based on a combination of fast LMD experiments and computer simulation of the water penetration is briefly introduced. Finally, the advantages and disadvantages of this approach are discussed.
KW  - Monolayer
KW  - Hydrolytic degradation
KW  - Enzymatic degradation
KW  - Biomaterial
KW  - Degradable polymer
Y1  - 2011
U6  - https://doi.org/10.5301/IJAO.2011.6401
SN  - 0391-3988
VL  - 34
IS  - 2
SP  - 123
EP  - 128
PB  - Wichtig
CY  - Milano
ER  - 
TY  - JOUR
A1  - Stiller, Burkhard
A1  - Karageorgiev, Peter
A1  - Perez, E.
A1  - Valez, M.
A1  - Reiche, Jürgen
A1  - Prescher, Dietrich
A1  - Dietzel, Birgit
A1  - Brehmer, Ludwig
T1  - Scanning kelvin microscopy as a tool for visualisation of optically induced molecular switching in azobenzene self assembling films
Y1  - 2000
SN  - 0142-2421
ER  - 
TY  - JOUR
A1  - Giebler, Rainer
A1  - Schulz, Burkhard
A1  - Reiche, Jürgen
A1  - Brehmer, Ludwig
A1  - Wühn, Mario
A1  - Wöll, Christoph
A1  - Smith, Andrew Phillip
A1  - Urquhart, Steven G.
A1  - Ade, Harald W.
A1  - Unger, Wolfgang E. S.
T1  - Near-edge x-ray absorption fine structure spectroscopy on ordered films of an amphiphilic derivate of 2,5- Diphenyl-1,3,4-oxadiazole
N2  - The surfaces of ordered films formed from an amphiphilic derivative of 2,5-diphenyl-1,3,4-oxadiazole by the Langmuir-Blodgett (LB) technique and organic molecular beam deposition (OMBD) were investigated by the use of near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. For the assignment of the spectral features of the C, N, and O K- edge absorption spectra, fingerprint spectra of poly(p-phenylene terephthalamide)(Kevlar), poly(ethylene terephthalate), poly(p-phenylene-1,3,4-oxadiazole), and 2,5-di- (pentadecyl)-1,3,4-oxadiazole, which contain related chemical moieties, were recorded. Ab initio molecular orbital calculations, performed with explicit treatment of the core hole, are used to support the spectral interpretations. Angle-resolved NEXAFS spectroscopy at the C, N, and O K-edges suggests a preferentially upright orientation of the oxadiazole derivative in the outermost layer of the films. X-ray specular reflectivity data and molecular modeling results suggest a similar interpretation.
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Freydank, Anke-Christine
A1  - Helms, Andreas
A1  - Geue, Thomas
A1  - Schulz, Burkhard
A1  - Brehmer, Ludwig
A1  - Stiller, Burkhard
A1  - Knochenhauer, Gerald
T1  - Vacuum deposition films of oxadiazole compounds : formation and structure investigation
N2  - The search for alternative routes of organic thin film formation is stimulated by the outstanding properties of these films in such fields as nonlinear optics, photonic data processing and molecular electronics. The formation of highly ordered multilayer structures by thermal vacuum deposition (VD) of organic compounds is an essential step toward the application of supramolecular organic architectures in technical systems. The VD of an amphiphilic substituted 2,5- diphenylene-1,3,4-oxadiazole 1 onto silicon substrates at defined temperature was used for the formation of ultrathin films. The structural data obtained for the VD-films of oxadiazole 1 by means of X-ray reflectivity, X-ray grazing incidence diffraction and atomic force microscopy (AFM) investigations indicate the formation of well ordered oxadiazole multilayers. The structure of the VD-multilayers is compared with that of Langmuir-Blodgett (LB) films and thermally treated LB-multilayers prepared from the same compound.
Y1  - 1999
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  - Schrader, Sigurd
A1  - Vismants, Z.
A1  - Dietzel, Birgit
A1  - Flueraru, C.
A1  - Prescher, Dietrich
A1  - Reiche, Jürgen
A1  - Motschmann, H.
A1  - Brehmer, Ludwig
T1  - Linear and nonlinear optical properties of Langmuir-Blodgett multilayers from chromophore-containing maleic acid anhydride polymers
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  - Akpo, Claudia
A1  - Weber, Edwin
A1  - Reiche, Jürgen
T1  - Synthesis, Langmuir and Langmuir-Blodgett film behaviour of new dendritic amphiphiles
JF  - New journal of chemistry
N2  - New amphiphilic compounds 1-9 that feature a construction with dendronized hydrophilic and hydrophobic segment groups connected to a specific aromatic or aliphatic spacer unit have been synthesized, following a modular building block strategy. The hydrophilic dendrons are typically branched elements with peripheral carboxylic groups, unlike the hydrophobic dendrons that contain peripheral alkyl chains as part of respective amide functions. The hydrophilic dendrons are in different generations of branching, while the hydrophobic dendrons are all in the first generation of branching (three terminal branching), but differ in the length of the alkyl chains, thus giving rise to designed structure and amphiphilic properties in the new compounds. The resulting surfactants are capable of forming well-defined Langmuir films of remarkable stability when spread from a solution onto an aqueous subphase. Nevertheless, specific packing behaviour and orientation of the amphiphilic molecules were found, depending on the molecular structure, as determined using analysis of the surface pressure-area (pi-A) isotherms. Langmuir-Blodgett transfer of the first monolayer from a pure water subphase to a clean silicon wafer proved possible for the amphiphiles of peripheral alkyl chain length C-12, while the amphiphiles with the longer alkyl chains failed, possibly due to the more rigid monolayers they form, impeding the transfer.
Y1  - 2006
U6  - https://doi.org/10.1039/b609645j
SN  - 1144-0546
SN  - 1369-9261
VL  - 30
SP  - 1820
EP  - 1833
PB  - RSC
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Köpf, Michael H.
A1  - Harder, Heiko
A1  - Reiche, Jürgen
A1  - Santer, Svetlana A.
T1  - Impact of temperature on the LB patterning of DPPC on Mica
JF  - Langmuir
N2  - The influence of the subphase temperature on the stripe pattern formation during Langmuir-Blodgett transfer (LB patterning) is investigated in a combined experimental and theoretical study. According to our experiments on the LB transfer of dipalmitoylphosphatidylcholine (DPPC) on planar mica substrates, even small temperature changes between 21.5 and 24.5 degrees C lead to significant changes in the monolayer patterns. For a constant surface pressure and dipper speed, the width of the stripes and the overall spatial period of the patterns increase with increasing subphase temperature. Because the stripe patterns are ascribed to alternating monolayer domains in the liquid-expanded and the liquid-condensed phases, the working regime for the formation of stripes is found to depend strongly on the respective surface pressure-area isotherm. These experimental findings are in accordance with the results of a theoretical investigation based on a model that takes hydrodynamics and the monolayer thermodynamics into account.
Y1  - 2011
U6  - https://doi.org/10.1021/la202728t
SN  - 0743-7463
VL  - 27
IS  - 20
SP  - 12354
EP  - 12360
PB  - American Chemical Society
CY  - Washington
ER  -