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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Self-organization of polymeric lipids with hydrophilic spacers in side groups and main chain : investigation in monolayers and multilayers

Laschewsky, André, Ringsdorf, H., Schmidt, G., Schneider, J. January 1987 (has links)
Several polymerizable lipids were synthesized and polymerized to amphiphilic homopolymers and to copolymers with the help of hydrophilic comonomers. The self-organization of these polymeric lipids was investigated in monolayers and Langmuir-Blodgett multilayers. The self-organization of these polymers in model membranes is due to hydrophilic spacer groups in the amphiphilic side groups as well as to hydrophilic spacer groups in the polymer backbone. Thus, highly ordered monolayers and LB-multilayers are easily obtained.
22

Polymerization of amphiphilic dienes in Langmuir-Blodgett multilayers

Laschewsky, André, Ringsdorf, H. January 1988 (has links)
Amphiphilic derivatives of octadiene and docosadiene were investigated in monolayers and Langmuir-Blodgett multilayers, with respect to their self-organization and their polymerization behavior. All amphiphiles investigated form monolayers. However, only acid and alcohol derivatives were able to build up multilayers. Those multilayers are rapidly photopolymerized in the layers via a two-step process: Irradiation with long-wavelength UV light yields soluble polymers, whereas additional irradiation with sfiort-wavelength UV light produces insoluble and presumably cross-linked polymers. The reaction meclianism is discussed according to the polymer characterization by UV spectroscopy, small-angle X-ray scattering, NMR spectroscopy, and gel permeation chromatography. All multilayers undergo structural changes during the polymerization; substantial changes result in defects in the polymerized layers as observed by scanning electron microscopy. In contrast to the acids and alcohols, the deposition of monolayers of the aldehyde derivatives did not yield well-ordered multilayers, but rather amorphous films. In this different film structure, the photopolymerization process differs from the one observed in multilayers.
23

Mixed polymeric monolayers and Langmuir-Blodgett multilayers with functional low molecular weight guest compounds

Laschewsky, André, Paulus, W., Ringsdorf, Helmut, Schuster, A., Frick, G., Mathy, A. January 1992 (has links)
Mixed monolayers and Langmuir-Blodgett multilayers of functional low molecular weight guest compounds, especially nonlinear optical (NLO) dyes, within the matrix of an amphotropic spacer polymer have been prepared. The polymer matrix enabled the transfer of guest compounds not capable of self-organizing at the air-water interface by themselves. The structure of the LB multilayers and the transfer process were studied by small angle X-ray scattering and UV-visible spectroscopy. Good NLO coefficients were found in the mixed films.
24

Thermal behaviour of polymeric Langmuir-Blodgett multilayers

Erdelen, C., Laschewsky, André, Ringsdorf, H., Schneider, J., Schuster, A. January 1989 (has links)
Langmuir-Blodgett multilayers of hydrocarbon and fluorocarbon polymers with hydrophilic spacer, lipid-polyelectrolyte complexes and mesogenic polymers have been prepared. The thermal behaviour of the multilayers was studied by small angle X-ray scattering, IR and UV—visible spectroscopy. Good thermal stabilities were found for the various classes of polymers. In addition, for both complexed multilayers and mesogenic polymer films, reorientation processes were observed.
25

Monolayers and Langmuir-Blodgett multilayers of discotic liquid crystals?

Laschewsky, André January 1989 (has links)
Contents: 1. Discotic Liquid Crystals 2. Monolayers and Langmuir-Blodgett Multilayers 3. Theoretical Considerations on the Molecular Packing of Discotic LCs in Monolayers and Multilayers 4. Spreading Experiments with Discotic LCs 5. LB-Multilayers of Discotic LCs 6. Polymeric Discotic LCs 7. Summary
26

Catecholamine-protein conjugates : isolation of 4-phenylphenoxazin-2-ones from oxidative coupling of N-acetyldopamine with alipathic amino acids

Peter, Martin G., Andersen, Svend Olav, Hartmann, Rudolf, Miessner, Merle, Roepstorff, Peter January 1992 (has links)
4-Phenylphenoxazinones were isolated after biomimetic oxidation, using diphenoloxidases of insect cuticle, mushroom tyrosinase, or after autoxidation of N-acetyldopamine (Image ) in the presence of β-alanine, β-alanine methyl ester or N-acetyl-L-lysine. They are formed presumably by addition of 2-aminoalkyl-5-alkylphenols to the o-quinone of biphenyltetrol which, in turn, arises from oxidative coupling of. The structures of present the first examples for the assembly of reasonably stable intermediates in the rather complex process of chemical modifications of aliphatic amino acid residues by o-quinones.
27

The use of the Langmuir-Blodgett technique to obtain ultra-thin polar films

Biddle, M. B., Rickert, S. E., Lando, J. B., Laschewsky, André January 1989 (has links)
The piezoelectric and pyroelectric properties of oriented films possessing dipole moments are increasingly being used in pressure, acoustic, thermal and optical devices. The performance of these devices in many applications may be enhanced by thin-film technology.The developing Langmuir-Blodgett thin-film deposition technique offers the opportunity to obtain highly oriented and uniform organic-based films in the 10–5000 nm thickness range. Special techniques must be used, however, to assemble these molecules in such a way as to result in polar multilayer films. Several possible deposition techniques are investigated, with one resulting in a polar and pyroelectric film about 50 nm thick.
28

Amphiphilic dyes for nonlinear optics: Dependence of second harmonic generation on functional group substitution

Bubeck, Christoph, Laschewsky, André, Lupo, Donald, Neher, Dieter, Ottenbreit, Petra, Paulus, Wolfgang, Prass, Werner, Ringsdorf, Helmut, Wegner, Gerhard January 1991 (has links)
No description available.
29

Polysoaps via alternating olefin/SO2 copolymers

Anton, Peter, Laschewsky, André January 1991 (has links)
Contents: Introduction Results and discussion - Monomers studied - Monomer properties - Polymerization, copolymer composition and general properties - Polymer properties in aqueous solution Conclusion Experimental part - Materials - Copolymerization with S02 (typical procedure) - Methods
30

The structural order of some novel ionic polymers : 1. X-ray scattering studies

Köberle, Peter, Laschewsky, André, Tsukruk, Vladimir January 1992 (has links)
A set of novel zwitterionic side-chain polyacrylates and polymethacrylates is studied by X-ray scattering. The structural order both in the short-range and long-range scale is investigated. The influence of the polymer backbone, of different locations of the ionic groups in isomeric polymers, of bound water and of added inorganic salts on the bulk structures is studied, and the observed rearrangements are analysed.

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