TY  - JOUR
A1  - Zehm, Daniel
A1  - Laschewsky, André
A1  - Heunemann, Peggy
A1  - Gradzielski, Michael
A1  - Prevost, Sylvain
A1  - Liang, Hua
A1  - Rabe, Jürgen P.
A1  - Lutz, Jean-Francois
T1  - Synthesis and self-assembly of amphiphilic semi-brush and dual brush block copolymers in solution and on surfaces
JF  - Polymer Chemistry
N2  - The combination of two techniques of controlled free radical polymerization, namely the reversible addition fragmentation chain transfer (RAFT) and the atom transfer radical polymerization (ATRP) techniques, together with the use of a macromonomer allowed the synthesis of symmetrical triblock copolymers, designed as amphiphilic dual brushes. One type of brush was made of poly(n-butyl acrylate) as soft hydrophobic block, i.e. characterized by a low glass transition temperature, while the other one was made of hydrophilic poly(ethylene glycol) (PEG). The new triblock polymers represent "giant surfactants" according to their molecular architecture. The hydrophobic and hydrophilic blocks microphase separate in the bulk. In aqueous solution, they aggregate into globular micellar aggregates, their size being determined by the length of the stretched polymer molecules. As determined by the combination of various scattering techniques for the dual brush copolymer, a rather compact structure is formed, which is dominated by the large hydrophobic poly(n-butyl acrylate) block. The aggregation number for the dual brush is about 10 times larger than for the "semi-brush" precursor copolymer, due to the packing requirements for the much bulkier hydrophobic core. On mica surfaces the triblock copolymers adsorb with worm-like backbones and stretched out side chains.
Y1  - 2011
U6  - https://doi.org/10.1039/c0py00200c
SN  - 1759-9954
VL  - 2
IS  - 1
SP  - 137
EP  - 147
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Prevost, Sylvain
A1  - Wattebled, Laurent
A1  - Laschewsky, André
A1  - Gradzielski, Michael
T1  - Formation of monodisperse charged vesicles in mixtures of cationic gemini surfactants and anionic SDS
JF  - Langmuir
N2  - The aggregation behavior of catanionics formed by the mixture of cationic geminis derived from dodecyltrimethylammonium chloride (DTAC) and anionic sodium dodecylsulfate (SDS) was studied by means of phase studies and comprehensive small-angle neutron scattering (SANS) experiments at 25 degrees C and 50 mM overall concentration. The results are compared to those for the previously studied SDS + DTAC system. Various gemini spacers of different natures and geometries were used, but all of them had similar lengths: an ethoxy bridge, a double bond, and an aromatic ring binding the two DTACs in three different substitutions (ortho, meta, and para). SANS and SAXS data analysis indicates that the spacer has no large effect on the spheroidal micelles of pure surfactants formed at low concentration in water; however, specific effects appear with the addition of electrolytes. Microstructures formed in the catanionic mixtures are rather strongly dependent on the nature of the spacer. The most important finding is that for the hydrophilic, flexible ethoxy bridge, monodisperse vesicles with a fixed anionic/cationic charge ratio (depending only on the surfactant in excess) are formed. Furthermore, the composition of these vesicles shows that strongly charged aggregates are formed. This study therefore provides new opportunities for developing tailor-made gemini surfactants that allow for the fine tuning of catanionic structures.
Y1  - 2011
U6  - https://doi.org/10.1021/la103976p
SN  - 0743-7463
VL  - 27
IS  - 2
SP  - 582
EP  - 591
PB  - American Chemical Society
CY  - Washington
ER  -