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Dive into the research topics where Olaf Karthaus is active.

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Featured researches published by Olaf Karthaus.


Thin Solid Films | 1998

Mesoscopic patterns of molecular aggregates on solid substrates

Norihiko Maruyama; Takeo Koito; Jin Nishida; Tetsuro Sawadaishi; X. Cieren; Kuniharu Ijiro; Olaf Karthaus; Masatsugu Shimomura

Abstract A two-dimensional micron-sized honeycomb structure was formed when a chloroform solution of an amphiphilic polymer was cast on solid surfaces at high atmospheric humidity. This simple method is widely applicable for patterning of molecular aggregates on solid surfaces. Mesoscopic patterns are demonstrated to be formed spontaneously from a variety of amphiphilic polyion complexes, amphiphilic covalent polymers, and organic–inorganic hybrid materials. Size and structure of the patterns can be regulated by concentration, atmospheric humidity, etc.


Liquid Crystals | 1991

Induction of a nematic columnar phase in a discotic hexagonal ordered phase forming system

Holger Bengs; Olaf Karthaus; Helmut Ringsdorf; C. Baehr; Martina Ebert; Joachim H. Wendorff

Abstract The induction of a nematic columnar phase in a discotic hexagonal ordered phase forming system is achieved by mixing hexakispentyloxytriphenylene 1 with a long chain derivative of trinitrofluorenone 3. The difference in chain length has a strong influence on the packing behaviour due to steric effects. The long hydrocarbon chains of the acceptor introduce a strong asymmetry into the electron donor acceptor complex. It could be shown by differential scanning calorimetry, optical microscopy and X-ray measurements that a nematic columnar phase is formed. In this mesophase the triphenylenes form columns but no hexagonal or orthorhombic lattice is built up. Each column behaves like a rod-like nematic mesogen. To prove that the long hexadecane alkyl chains of the acceptor are responsible for this induction, the acceptor 3 was mixed with the non-liquid-crystalline triphenylene derivative 2 containing six hexadecyloxy side groups. The long alkyl chains of the acceptor dissolve perfectly in the side chain...


Supramolecular Science | 1998

Mesoscopic pattern formation of nanostructured polymer assemblies

Norihiko Maruyama; Olaf Karthaus; Kuniharu Ijiro; Masatsugu Shimomura; Takeo Koito; Shinnichiro Nishimura; Tetsuro Sawadaishi; Norio Nishi; Seiichi Tokura

Abstract Hierarchical mesoscopic structures of the nanoscopic supramolecular assemblies, which consist of polyelectrolytes and bilayer-forming amphiphiles, are prepared by a simple and new solvent-casting method. Submicron scale 2-D structures, e.g. regular dots, stripes, and networks, are formed when highly diluted organic solutions of polymer assemblies are cast on solid surfaces. Dynamic mesoscopic regular structures, the so-called ‘dissipative structures’, formed in the non-equilibrium processes of solvent-casting are fixed as hierarchically structured polymer assemblies.


Materials Science and Engineering: C | 1999

Mesoscopic 2-D ordering of inorganic/organic hybrid materials

Olaf Karthaus; X. Cieren; Norihiko Maruyama; Masatsugu Shimomura

Abstract Organic–inorganic hybrid materials with micronsized (i.e., mesoscopic) network structures are expected to have interesting properties and applications in various fields, such as separation, catalysis, biomineralization, or quantum optics. Here a new method is introduced to produce thin films of two-dimensionally ordered honeycomb structures. Casting a chloroform solution of a mixture of organic amphiphiles with metal acetylacetonates or -alkoxides at high atmospheric humidity leads to the formation of a closely packed layer of water droplets on top of the organic solvent. The water acts as a template, After evaporation of the chloroform and the water, a honeycomb structure remains. Pyrolysis of the metal alkoxides films lead to the formation of microporous metal oxide (e.g., anatase, one of the catalytic active titanium oxides).


Liquid Crystals | 1993

Infrared absorption study of hexapentyloxytriphenylene A discotic liquid crystal

G. Kruk; Antoni Kocot; R. Wrzalik; J. K. Vij; Olaf Karthaus; Helmut Ringsdorf

Abstract Fourier transform infrared absorption (FTIR) spectroscopy has been used to study a discotic liquid crystal. IR spectra are reported as a function of temperature for hexapentyloxytriphenyle...


Langmuir | 2010

Preparation of patterned zinc oxide films by breath figure templating.

Kenichi Kon; Chris Norman Brauer; Kosuke Hidaka; Hans-Gerd Löhmannsröben; Olaf Karthaus

A large variety of microporous polymer films can be prepared by the breath figure technique. Here, we report on its use for the formation of microporous zinc oxide films. Zinc acetylacetonate, a zinc oxide precursor, is either dissolved in a polymer solution that is cast at high humidity to form microporous films or is vacuum evaporated onto a preformed microporous polymer film. Annealing leads to the pyrolysis of the organic material and the formation of zinc oxide films, which show increased photocatalytic activity as compared to unstructured films.


Liquid Crystals | 1990

2H NMR studies of phase behaviour and molecular motions of doped discotic liquid-crystalline systems

Wolfgang Kranig; C. Boeffel; Hans Wolfgang Spiess; Olaf Karthaus; Helmut Ringsdorf; Renate Wüstefeld

Abstract A discotic triphenylene monomer as well as a dimer and a main chain polymer, all substituted with heptyloxy side groups, were doped with an electron acceptor (2,4,7-trinitrofluorenone (TNF)) to give charge transfer complexes. These doped systems were aligned in a magnetic field, thus proving their liquid crystallinity. 2H NMR measurements show that the electron acceptor molecules are incorporated into the columns built of triphenylene cores. In the charge transfer complex with the triphenylene monomer almost all the electron acceptor molecules stack in the columns even close to the clearing temperature T 1, while for the dimer and especially for the polymer a significant fraction of the TNF molecules exhibits isotropic motion, which is attributed to their location in the region between the columns, already way below T 1. This isotropically distributed part increases on approaching T 1. Fast rotation of the discs around their column axes takes place in the monomer and is quenched in the dimer and ...


Applied Physics Letters | 2004

Electroluminescence from self-organized microdomes

Olaf Karthaus; Chihaya Adachi; Shigeya Kurimura; Takahito Oyamada

The preparation of a self-organized, microstructured organic electroluminescent device is reported. A dewetting process is used to form (sub)micrometer-sized dewetted patches (“domes”) of a hole transport material (tolyl-phenyl-diaminobiphenyl, TPD) on an indium-tin-oxide electrode. The domes are regular in size and spacing. Evaporation of an electron transport material (tris-8-hydroxyquinoline aluminum, Alq3) and an Mg/Ag top electrode leads to a device with electroluminescing spots of micrometer dimensions and a spacing of a few micrometers.


Thin Solid Films | 1992

Mono- and multilayers made from discotic liquid crystals

Mark Van der Auweraer; C. Catry; L.Feng Chi; Olaf Karthaus; Wolfgang Knoll; Helmut Ringsdorf; M. Sawodny; C. Urban

Abstract Some discotic liquid crystals can form stable monolayers at the air-water interface. Depending on their chemical structure two different arrangements of the discs are possible, edge-on and side-on, which crucially influence the mono- and multilayer behaviour. It is found that the rather unpolar triphenylenes prefer monolayers of the edge-on type. The monolayer stability is improved by incorporation of hydrophilic groups into the side group region of the molecules or by polymer fixation. LB multilayers can be formed on solid supports, which show photoconductivity. In contrast, the more polar class of disc-like phloroglucinols show a more complex behaviour at the air-water interface. Depending on the substitution pattern, edge-on or side-on arrangements can occur. On compression beyond the classical collapse point, defined multilayers were obtained at the air-water interface, which were investigated by surface plasmon spectroscopy.


Molecular Crystals and Liquid Crystals | 1998

Photonic and Electronic Applications of Mesoscopic Polymer Assemblies

Masatsugu Shimomura; Takeo Koito; Norihiko Maruyama; Keiko Arai; Jin Nishida; Lars Gråsjö; Olaf Karthaus; Kuniharu Ijiro

Abstract Mesoscopic two-dimensional patterns, regular dots, stripes, and honeycomb networks are formed when dilute organic solutions of polymers are cast on solid surfaces. Dynamic patterns, so-called “dissipative structures”, formed in the non-equilibrium thermodynamic process of solvent evaporation, are fixed as the two-dimensional polymer patterns on substrates. Some photonic and electronic applications of the mesoscopic polymer patterns are described in this article.

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Masatsugu Shimomura

Chitose Institute of Science and Technology

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Yuji Kiyono

Chitose Institute of Science and Technology

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Kazuaki Kaga

Chitose Institute of Science and Technology

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Yuichi Hashimoto

Chitose Institute of Science and Technology

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