TY - JOUR A1 - Garnier, Sebastien A1 - Laschewsky, André T1 - Synthesis of new amphiphilic diblock copolymers and their self-assembly in aqueous solution N2 - Amphiphilic diblock copolymers composed of poly(butyl acrylate) as the hydrophobic block with a low glass transition temperature and of six different hydrophilic blocks (one anionic, one cationic, and four nonionic hydrophilic blocks) are prepared via reversible addition fragmentation chain transfer (RAFT) polymerization. The nonionic hydrophilic blocks comprise in addition to the classical poly(dimethylacrylamide), the thermally sensitive poly(N- acryloylpyrrolidine), and a comb-type polymer made of a poly(ethylene glycol acrylate) macromonomer, as well as a new strongly hydrophilic sulfoxide polymer. The "living" character of the polymerizations is supported by very low polydispersity indexes and a good correlation between the molar masses obtained and the theoretically expected ones. Two distinct glass transition temperatures were found by differential scanning calorimetry for the block copolymers, suggesting the immiscibility of the blocks in bulk. The self-assembling properties of the amphiphilic diblock copolymers in aqueous and organic media were studied by nuclear magnetic resonance spectroscopy and dynamic light scattering, as a function of the polarity of the hydrophilic blocks, the ratio of the lengths of the two blocks, and the overall molar mass of the diblock copolymers. Micellelike aggregates with diameters from 25 to 100 mn in water are found, as well as inverse micelles in organic solvents. The length of the hydrophobic block seems to be the main factor governing the size of the aggregates in water. The aggregates are very stable upon dilution and temperature cycles. For large hydrophobic blocks, big structures are observed in addition to small micelles initially after the dispersion in water. As the big aggregates disappear slowly, the micellization process seems thermodynamically favored. If two populations of micelles made from different block copolymers are brought together, "mixed" micelles are formed. The implicit exchange of polymers proves the dynamic character of the micellar systems based on poly(butyl acrylate) as hydrophobic block Y1 - 2005 ER - TY - JOUR A1 - Delorme, Nicolas A1 - Dubois, Monique A1 - Garnier, Sebastien A1 - Laschewsky, André A1 - Weinkamer, Richard A1 - Zemb, Thomas A1 - Fery, Andreas T1 - Surface immobilization and mechanical properties of catanionic hollow faceted polyhedrons N2 - We report here for the first time on surface immobilization of hollow faceted polyhedrons formed from catanionic surfactant mixtures. We find that electrostatic interaction with the substrate dominates their adhesion behavior. Using polyelectrolyte coated surfaces with tailored charge densities, polyhedrons can thus be immobilized without complete spreading, which allows for further study of their mechanical properties using AFM force measurements. The elastic response of individual polyhedrons can be locally resolved, showing pronounced differences in stiffness between faces and vertexes of the structure, which makes these systems interesting as models for structurally similar colloidal scale objects such as viruses, where such effects are predicted but cannot be directly observed due to the smaller dimensions. Elastic constants of the wall material are estimated using shell and plate deformation models and are found to be a factor of 5 larger than those for neutral lipidic bilayers in the gel state. We discuss the molecular origins of this high stiffness Y1 - 2006 UR - http://pubs.acs.org/journal/jpcbfk U6 - https://doi.org/10.1021/Jp054473+ SN - 1520-1758 ER - TY - JOUR A1 - Mertoglu, Murat A1 - Garnier, Sebastien A1 - Laschewsky, André A1 - Skrabania, Katja A1 - Storsberg, J. T1 - Stimuli responsive amphiphilic block copolymers for aqueous media synthesised via reversible addition fragmentation chain transfer polymerisation (RAFT) N2 - A series of RAFT agents was synthesised, and used to prepare various ionic. non-ionic and zwitterionic water- soluble polymers, in organic as well as in aqueous media. The RAFT process proved to be a powerful method to prepare functional polymers of complex structure. such as amphiphilic diblock and triblock copolymers. This includes polymers containing one or even two stimuli-sensitive hydrophilic blocks. Switching the hydrophilic character of a single or of several blocks by changing the PH, the temperature or the salt content demonstrated the variability of the molecular designs suited for stimuli-sensitive polymeric amphiphiles, and exemplified the concept of multiple-sensitive systems. (c) 2005 Published by Elsevier Ltd Y1 - 2005 SN - 0032-3861 ER - TY - JOUR A1 - Garnier, Sebastien A1 - Laschewsky, André A1 - Storsberg, J T1 - Polymeric surfactants : novel agents with exceptional properties N2 - This article presents recent progress in the field of polymeric surfactants made of permanently amphiphilic block copolymers or of stimulus-sensitive ones. We highlight key points in the design of amphiphilic macromolecules, to yield polymer surfactants with tailor-made properties, as well as recently developed and still challenging application fields for this new class of surfactants. The efficiency boosting of amphiphilic block copolymers as co-surfactants in microemulsions is discussed, as are surface modification by polymer surfactants, and stabilization of dispersions. Moreover, the use of block copolymers in nanosciences is presented, for instance as a tool for nanomaterial fabrication, or for biomedical and cosmetic applications in bio-nanotechnology. Finally, self-assembly and applications of some newly developed "exotic" amphiphilic block copolymer structures as new surface-active materials will be highlighted Y1 - 2006 UR - http://www.tsdjournal.com/ SN - 0932-3414 ER - TY - JOUR A1 - Garnier, Sebastien A1 - Laschewsky, Andre T1 - Non-ionic amphiphilic block copolymers by RAFT-polymerization and their self-organization JF - Colloid and polymer science : official journal of the Kolloid-Gesellschaft N2 - Water-soluble, amphiphilic diblock copolymers were synthesized by reversible addition fragmentation chain transfer polymerization. They consist of poly(butyl acrylate) as hydrophobic block with a low glass transition temperature and three different nonionic water-soluble blocks, namely, the classical hydrophilic block poly(dimethylacrylamide), the strongly hydrophilic poly(acryloyloxyethyl methylsulfoxide), and the thermally sensitive poly(N-acryloylpyrrolidine). Aqueous micellar solutions of the block copolymers were prepared and characterized by static and dynamic light scattering analysis (DLS and SLS). No critical micelle concentration could be detected. The micellization was thermodynamically favored, although kinetically slow, exhibiting a marked dependence on the preparation conditions. The polymers formed micelles with a hydrodynamic diameter from 20 to 100 nm, which were stable upon dilution. The micellar size was correlated with the composition of the block copolymers and their overall molar mass. The micelles formed with the two most hydrophilic blocks were particularly stable upon temperature cycles, whereas the thermally sensitive poly(N-acryloylpyrrolidine) block showed a temperature-induced precipitation. According to combined SLS and DLS analysis, the micelles exhibited an elongated shape such as rods or worms. It should be noted that the block copolymers with the most hydrophilic poly(sulfoxide) block formed inverse micelles in certain organic solvents. KW - macrosurfactants KW - block copolymers KW - micelles KW - inverse micelles KW - sulfoxide Y1 - 2006 U6 - https://doi.org/10.1007/s00396-006-1484-9 SN - 0303-402X VL - 284 SP - 1243 EP - 1254 PB - Springer CY - Berlin ER - TY - JOUR A1 - Garnier, Sebastien A1 - Laschewsky, André T1 - New amphiphilic diblock copolymers : surfactant properties and solubilization in their micelles N2 - Several series of amphiphilic diblock copolymers are investigated as macrosurfactants in comparison to reference low-molar-mass and polymeric surfactants. The various copolymers share poly(butyl acrylate) as a common hydrophobic block but are distinguished by six different hydrophilic blocks (one anionic, one cationic, and four nonionic hydrophilic blocks) with various compositions. Dynamic light scattering experiments indicate the presence of micelles over the whole concentration range from 10(-4) to 10 g(.)L(-1). Accordingly, the critical micellization concentrations are very low. Still, the surface tension of aqueous solutions of block copolymers decreases slowly but continuously with increasing concentration, without exhibiting a plateau. The longer the hydrophobic block, the shorter the hydrophilic block, and the less hydrophilic the monomer of the hydrophilic block is, the lower the surface tension is. However, the effects are small, and the copolymers reduce the surface tension much less than standard low-molar-mass surfactants. Also, the copolymers foam much less and even act as anti-foaming agents in classical foaming systems composed of standard surfactants. The copolymers stabilize O/W emulsions made of methyl palmitate as equally well as standard surfactants but are less efficient for O/W emulsions made of tributyrine. However, the copolymer micelles exhibit a high solubilization power for hydrophobic dyes, probably at their core-corona interface, in dependence on the initial geometry of the micelles and the composition of the block copolymers. Whereas micelles of copolymers with strongly hydrophilic blocks are stable upon solubilization, solubilization-induced micellar growth is observed for copolymers with moderately hydrophilic blocks Y1 - 2006 UR - http://pubs.acs.org/journal/langd5 U6 - https://doi.org/10.1021/La0600595 SN - 0743-7463 ER - TY - JOUR A1 - Ortmann, Thomas A1 - Ahrens, Heiko A1 - Milewski, Sven A1 - Lawrenz, Frank A1 - Groening, Andreas A1 - Laschewsky, André A1 - Garnier, Sebastien A1 - Helm, Christiane A. T1 - Lipid monolayers with adsorbed oppositely charged polyelectrolytes: Influence of reduced charge densities JF - Polymers N2 - Polyelectrolytes in dilute solutions (0.01 mmol/L) adsorb in a two-dimensional lamellar phase to oppositely charged lipid monolayers at the air/water interface. The interchain separation is monitored by Grazing Incidence X-ray Diffraction. On monolayer compression, the interchain separation decreases to a factor of two. To investigate the influence of the electrostatic interaction, either the line charge density of the polymer is reduced (a statistic copolymer with 90% and 50% charged monomers) or mixtures between charged and uncharged lipids are used (dipalmitoylphosphatidylcholine (DPPC)/dioctadecyldimethylammonium bromide (DODAB)) On decrease of the surface charge density, the interchain separation increases, while on decrease of the linear charge density, the interchain separation decreases. The ratio between charged monomers and charged lipid molecules is fairly constant; it decreases up to 30% when the lipids are in the fluid phase. With decreasing surface charge or linear charge density, the correlation length of the lamellar order decreases. KW - lipid monolayer KW - polyelectrolyte adsorption KW - statistical copolymer KW - two-dimensional phases KW - surface charge KW - nematic phase KW - grazing incidence X-ray diffraction Y1 - 2014 U6 - https://doi.org/10.3390/polym6071999 SN - 2073-4360 VL - 6 IS - 7 SP - 1999 EP - 2017 PB - MDPI CY - Basel ER - TY - JOUR A1 - Laschewsky, André A1 - Garnier, Sebastien A1 - Kirsten, Juliane A1 - Mertoglu, Murat A1 - Skrabania, Katja A1 - Lutz, Jean-Francois T1 - Comb-like polymeric surfactants by combining block and graft copolymer architectures Y1 - 2006 SN - 0065-7727 ER -