TY - GEN A1 - Albrecht, O. A1 - Cumming, W. A1 - Kreuder, W. A1 - Laschewsky, André A1 - Ringsdorf, Helmut T1 - Monolayers of rod-shaped and disc-shaped liquid crystalline compounds at the air-water interface N2 - Calamitic (rod-shaped) and discotic (disc-shaped) thermotropic liquid crystalline (LC) compounds were spread at the air-water interface, and their ability to form monolayers was studied. The calamitic LCs investigated were found to form monolayers which behave analogously to conventional amphiphiles such as fatty acids. The spreading of the discotic LCs produced monolayers as well, but with a behaviour different from classical amphiphiles. The areas occupied per molecule are too small to allow the contact of all hydrophilic groups with the water surface and the packing of all hydrophobic chains. Various molecular arrangements of the discotics at the water surface to fit the spreading data are discussed. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 079 KW - Monolayers KW - liquid crystals KW - discotics Y1 - 1986 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17124 ER - TY - GEN A1 - Anton, Peter A1 - Köberle, Peter A1 - Laschewsky, André T1 - Recent developments in the field of micellar polymers N2 - This article describes recent achievements in the field of micellar polymers, or polysoaps. Taking advantage of zwitterionic model polymers, systematic variations of the molecular architecture have provided an improved understanding of the relationship between the molecular structure of the polymers and their key properties such as surface activity and solubilization capacity. Useful rules are established, which take into account much of the previous data in the literature. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 090 Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17263 ER - TY - GEN A1 - Anton, Peter A1 - Laschewsky, André T1 - Zwitterionic polysoaps with reduced density of surfactant side groups N2 - Several zwitterionic polymers were prepared by radical homopolymerization of surfactant monomers which bear diallyl, diene or vinylcyclopropane moieties. These polymer systems were complemented by alternating copolymers of appropriate zwitterionic vinyl compounds. Thus, polymers with reduced (as compared with simple vinylic homopolymers, or statistical copolymers) and well defined density of surfactant side groups are obtained. The solubilities found for these polymers are dominated by polymer geometry rather than by the balance of hydrophilic and hydrophobic fragments, thus corroborating a main-chain spacer model proposed recently. All water-soluble polymers exhibit characteristic features of classical polysoaps, as shown by surface tension measurements and by solubilization of hydrophobic dyes. In contrast, the water-insoluble copolymers are capable to form stable monolayers at the air-water interface. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 091 Y1 - 1993 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17301 ER - TY - GEN A1 - Anton, Peter A1 - Laschewsky, André T1 - Solubilization by polysoaps N2 - The aqueous solubilization power of several series of micellar homopolymers and copolymers (polysoaps) is investigated. Using five insoluble or poorly water-soluble dyes, comparisons of the capacities are made with respect ot the influence of structural variables such as the polymer backbone, the polymer geometry, the comonomer content, and the charge of the hydrophilic group. Some guidelines for polysoap structures suited for efficient solubilization are established. Noteworthy is that the solubilization capacities of the polysoaps are neither linked to the ability to reduce the surface tension of water, nor to the polarity of the solubilization sites deduced from spectroscopic probes. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 083 KW - Micellar polymers KW - polysoaps KW - solubilization Y1 - 1994 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17327 ER - TY - GEN A1 - Anton, Peter A1 - Laschewsky, André T1 - Polysoaps via alternating olefin/SO2 copolymers N2 - 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 T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 088 Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17216 ER - TY - GEN A1 - Anton, Peter A1 - Laschewsky, André A1 - Ward, M. D. T1 - Solubilization control by redox-switching of polysoaps N2 - Reversible changes in the self-organization of polysoaps may be induced by controlling their charge numbers via covalently bound redox moieties. This is illustrated with two viologen polysoaps, which in response to an electrochemical stimulus, change their solubility and aggregation in water, leading from homogeneously dissolved and aggregated molecules to collapsed ones and vice verse. Using the electrochemical quartz crystal microbalance (EQCM), it could be shown that the reversibility of this process is better than 95% in 16 cycles. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 084 KW - Quartz Crystal KW - microbalance KW - films KW - Electrochemistry KW - viologen Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17336 ER - TY - GEN A1 - Biddle, M. B. A1 - Rickert, S. E. A1 - Lando, J. B. A1 - Laschewsky, André T1 - The use of the Langmuir-Blodgett technique to obtain ultra-thin polar films N2 - 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. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 098 Y1 - 1989 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17185 ER - TY - GEN A1 - Bubeck, Christoph A1 - Laschewsky, André A1 - Lupo, Donald A1 - Neher, Dieter A1 - Ottenbreit, Petra A1 - Paulus, Wolfgang A1 - Prass, Werner A1 - Ringsdorf, Helmut A1 - Wegner, Gerhard T1 - Amphiphilic dyes for nonlinear optics: Dependence of second harmonic generation on functional group substitution T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 082 Y1 - 1991 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17201 ER - TY - GEN A1 - Cochin, Didier A1 - Hendlinger, P. A1 - Laschewsky, André T1 - Polysoaps with fluorocarbon hydrophobic chains N2 - A series of amphiphilic copolymers is prepared by copolymerization of choline methacrylate with 1,1,2,2-tetrahydroperfluorooctyl methacrylate in varying amounts. The copolymers bearing fluorocarbon chains are studied concerning their effects on viscosity, solubilization and surface activity in aqueous solution, exhibiting a general behavior characteristic for polysoaps. The results are compared with the ones obtained for an analogous series of amphiphilic copolymers bearing hydrocarbon chains. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 085 KW - Amphiphilic polymers KW - fluorocarbon polymers KW - associating polymers KW - polysoaps Y1 - 1995 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17347 ER - TY - GEN A1 - Elbert, R. A1 - Laschewsky, André A1 - Ringsdorf, H. T1 - Hydrophilic spacer groups in polymerizable lipids: formation of biomembrane models from bulk polymerized lipids N2 - A variety of polymerizable lipids containing a hydrophilic spacer group between the reactive group and the main amphiphilic structure have been synthesized. They were investigated in monolayers, liposomes, and multilayers. When the spacer concept was used, efficient decoupling of the motions of the polymeric chain and the amphiphilic side groups is achieved. Thus, the often found loss of the important fluid phases by polymerization is avoided. Polymeric monolayers of the spacer lipid, prepared either by polymerization in the monolayer or by spreading of prepolymerized lipid, exhibit nearly identical surface pressure-area diagrams. Most distinctly, the successful decoupling of the motions of the polymer main chain and the membrane forming amphiphilic side groups is demonstrated by the self-organization of bulk polymerized spacer lipids to polymeric liposomes. In addition, spacer lipids are able to build polymeric Langmuir-Blodgett multilayers. The decoupling of the polymer main chain and the membrane-forming amphiphilic side groups enables the deposition of already polymeric monolayers onto supports to form defined multilayers. If, alternatively, monomeric monolayers are deposited and polymerized on the support, defects in the layers due to structural changes during the polymerization are avoided by the flexible spacer group. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 095 Y1 - 1985 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17361 ER -