TY - JOUR A1 - Baussard, Jean-Francois A1 - Habib-Jiwan, Jean-Louis A1 - Laschewsky, André T1 - Enhanced Förster resonance energy transfer in electrostatically self-assembled multilayer films made from new fluorescent labeled polycations Y1 - 2003 ER - TY - JOUR A1 - Baussard, Jean-Francois A1 - Habib-Jiwan, Jean-Louis A1 - Laschewsky, André A1 - Mertoglu, Murat A1 - Storsberg, Joachim T1 - New chain transfer agents for reversible addition-fragmentation chain transfer (RAFT) polymerisation in aqueous media : 1. Synthesis and stability in water N2 - New chain transfer agents for free radical polymerisation via reversible addition-fragmentation chain transfer (RAFT) were synthesised that are particularly suited for aqueous solution polymerisation. The new compounds bear dithioester and trithiocarbonate moieties as well as permanently ionic groups to confer solubility in water. Their stability against hydrolysis was studied, and compared with the one of a frequently employed water-soluble RAFT agent, using UV-Vis-spectroscopy and H-1-NMR measurements. An improved resistance to hydrolysis was found for the new RAFT agents compared to the reference one, providing good stabilities in the pH range between 1 and 8, and up to temperatures of 70 degreesC. (C) 2004 Elsevier Ltd. All rights reserved Y1 - 2004 ER - TY - JOUR A1 - Laschewsky, André A1 - Mallwitz, Frank A1 - Baussard, Jean-Francois A1 - Cochin, Didier A1 - Fischer, Peter A1 - Habib-Jiwan, Jean-Louis A1 - Wischerhoff, Erik T1 - Aggregation phenomena in polyelectrolyte multilayers made from polyelectrolytes bearing bulky functional, hydrophobic fragments N2 - The functionalization of polyelectrolyte multilayers often implies the use of bulky functional fragments, attached to a standard polyelectrolyte matrix. Despite of the high density of non-charged, often hydrophobic substituents, regular film growth by sequential adsorption proceeds easily when an appropriate polyelectrolyte counter ion is chosen. However, the functional fragments may cluster or aggregate. This complication is particularly evident when using chromophores and fluorophores as bulky pendant groups. Attention has to be paid to this phenomenon for the design of functional polyelectrolyte films, as aggregation may modify crucially the properties. The use of charged spacer groups does not necessarily suppress the aggregation of functional side groups. Still, clustering and aggregation depend on the detailed system employed, and are not obligatory. In the case of cationic poly(acrylamide)s labeled with naphthalene and pyrene fluorophores, for instance, the polymers form intramolecular hydrophobic associates in solution, as indicated by strong excimer formation. But the polymers can undergo a conformational rearrangement upon adsorption so that they are decoiled in the adsorbed films. Analogous observations are made for polyanions bearing mesogenic biphenyls fragments. In contrast, polycations functionalized with the dye coumarin 343 show little aggregation in solution, but a marked aggregation in the ESA films Y1 - 2004 ER - TY - JOUR A1 - Laschewsky, André A1 - Wattebled, Laurent A1 - Arotcarena, Michel A1 - Habib-Jiwan, Jean-Louis A1 - Rakotoaly, R. H. T1 - Synthesis and properties of cationic oligomeric surfactants N2 - Three series of new oligomeric cationic surfactants were synthesized. These amphiphiles are trimeric and tetrameric oligomeric quaternary ammonium chlorides, with spacer groups of different lengths separating the individual surfactant fragments. The properties of the compounds, such as Krafft temperatures, surface activity, micellization, viscosifying effects, foaming and solubilizing capacity, are studied. The influence of the degree of oligomerization and of the spacer group on the surfactant properties is discussed, in comparison with the analogous standard monomeric and dimeric ("gemini") surfactants. Typically, the evolution of the properties observed from standard to dimeric surfactants progresses with the trimers and tetramers, resulting for instance in extremely low critical micellization concentrations Y1 - 2005 SN - 0743-7463 ER - TY - JOUR A1 - Rullens, F A1 - Vuillaume, Pascal Y. A1 - Moussa, Alain A1 - Habib-Jiwan, Jean-Louis A1 - Laschewsky, André T1 - Ordered polyelectrolyte "Multilayers". 7. Hybrid films self-assembled from fluorescent and smectogenic poly(diallylammonium) salts and delaminated clay N2 - Homopolymers were prepared from diallylammonium monomers bearing 4-methylcoumarin and 4-cyanobiphenyl as fluorescent and mesogenic side groups, as well as their copolymers with diallyldimethylammonium chloride (DADMAC). Organic-inorganic hybrid films were electrostatically self-assembled via the layer-by-layer technique on silicon wafers and quartz plates from the chromophore-bearing polymers and an exfoliated synthetic hectorite. Photophysical studies performed in solution as well as in the self-assembled films demonstrated only a weak tendency for aggregation of the chromophores in the macromolecules. Moreover, assemblies made from the polymers carrying the cyanobiphenyl mesogen were found to exhibit a pronounced internal order Y1 - 2006 UR - http://pubs.acs.org/doi/full/10.1021/cm060209x U6 - https://doi.org/10.1021/Cm060209x ER - TY - JOUR A1 - Wattebled, Laurent A1 - Laschewsky, André A1 - Moussa, Alain A1 - Habib-Jiwan, Jean-Louis T1 - Aggregation numbers of cationic oligomeric surfactants : A time-resolved fluorescence quenching study N2 - The micelle aggregation numbers (N-agg) of several series of cationic oligomeric surfactants were determined by time-resolved fluorescence quenching (TRFQ) experiments, using advantageously 9,10-dimethylanthracene as fluorophore. The study comprises six dimeric ("gemini"), three trimeric, and two tetrameric surfactants, which are quaternary ammonium chlorides, with medium length spacer groups (C-3-C-6) separating the individual surfactant fragments. Two standard cationic surfactants served as references. The number of hydrophobic chains making up a micellar core is relatively low for the oligomeric surfactants, the spacer length playing an important role. For the dimers, the number decreases from 32 to 21 with increasing spacer length. These numbers decrease further with increasing degree of oligomerization down to values of about 15. As for many conventional ionic surfactants, the micelles of all oligomers studied grow only slightly with the concentration, and they remain in the regime of small micelles up to concentrations of at least 3 wt %. Y1 - 2006 UR - http://pubs.acs.org/doi/full/10.1021/la052414h U6 - https://doi.org/10.1021/La052414h ER -