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 - 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 - Köpf, Michael H. A1 - Harder, Heiko A1 - Reiche, Jürgen A1 - Santer, Svetlana 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 - 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 - 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 - 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 - 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 - 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 -