@article{KoetzBruehlKosmellaetal.1997, author = {Koetz, Joachim and Br{\"u}hl, Iris and Kosmella, Sabine and Reiche, J{\"u}rgen and Tiersch, Brigitte}, title = {Polyelectrolyte Complex Formation in Lamellar Liquid Crystalline Systems}, year = {1997}, abstract = {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.}, language = {en} } @article{JanietzHofmannReiche1994, author = {Janietz, Dietmar and Hofmann, Dieter and Reiche, J{\"u}rgen}, title = {Molecular organization of amphiphilic disc-shaped penta-alkynes in LB-mono- and multilayers}, year = {1994}, abstract = {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.}, language = {en} } @article{ReicheKnochenhauer1994, author = {Reiche, J{\"u}rgen and Knochenhauer, Gerald}, title = {Numerische Simulation und R{\"o}ntgenbeugung an thermisch aufgedampften Multischichten perfluorierter Fetts{\"a}uren}, year = {1994}, language = {de} } @article{ReicheDietelLemmetyinenetal.1992, author = {Reiche, J{\"u}rgen and Dietel, Reinhard and Lemmetyinen, Helge and Janietz, Dietmar and Lemmetyinen, Helge and Brehmer, Ludwig}, title = {Edge-on Langmuir-Blodgett multilayers derived from disc-shaped multiyne mesogens}, year = {1992}, abstract = {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.}, language = {en} } @article{PenacoradaSoutoKatholyetal.1998, author = {Pe{\~n}acorada, Florencio and Souto, Jorge and Katholy, Stefan and Saja, Jos{\´e}-Antonio de and Reiche, J{\"u}rgen}, title = {Structure of Langmuir monolayers of substituted phthalocyanines}, year = {1998}, abstract = {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.}, language = {en} } @article{ReicheZetzscheHelmsetal.1997, author = {Reiche, J{\"u}rgen and Zetzsche, Thomas and Helms, Andreas and Freydank, Anke-Christine and Knochenhauer, Gerald and Schulz, Burkhard and Brehmer, Ludwig}, title = {Organized molecular films of oxadiazole compounds formed by vacuum deposition}, year = {1997}, language = {en} } @article{WuestneckReicheFoerster1997, author = {W{\"u}stneck, Rainer and Reiche, J{\"u}rgen and F{\"o}rster, Stephan}, title = {Surface dilational behavior of docosanic acid monolayers spread on the surface of drops of polymer solutions}, year = {1997}, abstract = {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.}, language = {en} } @article{PenacoradaAngelovaKamusewitzetal.1995, author = {Penacorada, Florencio and Angelova, Angelina and Kamusewitz, Helmut and Reiche, J{\"u}rgen and Brehmer, Ludwig}, title = {Scanning Force Microscopy and Wetting study of the Surface Modification of a Polypropylene Mambrane by Means of Langmuir-Blodgett Film Deposition}, year = {1995}, abstract = {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.}, language = {en} } @article{ReicheJanietzBarberkaetal.1995, author = {Reiche, J{\"u}rgen and Janietz, Dietmar and Barberka, Thomas Andreas and Hofmann, Dieter and Brehmer, Ludwig}, title = {Comprehensive structure investigation of Langmuir-Blodgett films of disc-shaped molecules}, year = {1995}, abstract = {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.}, language = {en} } @article{PenacoradaReicheKatholyetal.1995, author = {Penacorada, Florencio and Reiche, J{\"u}rgen and Katholy, Stefan and Brehmer, Ludwig and Rodriguez-Mendez, Maria-Luisa}, title = {Monolayers and multilayers of uranyl arachidate : 1. study of the interaction of dissolved uranyl ions with arachidic acid Langmuir monolayers}, year = {1995}, abstract = {Langmuir monolayers of arachidic acid have been prepared on a subphase containing uranyl ions (O-U-O){\´y}+. 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 Cd{\´y}+ 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 Cd{\´y}+. 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.}, language = {en} }