TY  - JOUR
A1  - Koetz, Joachim
A1  - Bahnemann, Jennifa
A1  - Lucas, Gordon
A1  - Tiersch, Brigitte
A1  - Kosmella, Sabine
T1  - Polyelectrolyte-modified microemulsions as new templates for the formation of nanoparticles
N2  - The paper is focused on the formation and redispersion of monodisperse BaSO4 nanoparticles in polyelectrolyte- modified microemulsions. It is shown that a cationic polyelectrolyte of low molar mass, e.g. poly(dially1dimethylammonium chloride) (PDADMAC), can be incorporated into the individual inverse microemulsion droplets (L2 phase) consisting of heptanol, water, and an amphoteric surfactant with a sulfobetaine head group. These PDADMAC- filled microemulsion droplets can be successfully used as a template phase for the nanoparticle formation. The monodisperse BaSO4 nanoparticles are produced by a simple mixing procedure and can be redispersed after solvent evaporation without a change in particle dimensions. Dynamic and electrophoretical light scattering in combination with sedimentation experiments in the analytical Ultracentrifuge of the redispersed powder show polyelectrolyte-stabilized nanoparticles with diameters of about 6 nm. The polyelectrolyte shows a "size control effect", which can be explained by the polyelectrolyte-surfactant interactions in relation to the polyelectrolyte-nanoparticle interactions during the particle growth, solvent evaporation and redispersion process. However, the approach used here opens away to produce different types of polyelectrolyte-stabilized nanoparticles (including rare metals, semiconductors, carbonates or oxides) of very small dimensions. (C) 2004 Elsevier B.V. All rights reserved
Y1  - 2004
SN  - 0927-7757
ER  - 
TY  - JOUR
A1  - Robertson, Daniela
A1  - Hellweg, Thomas
A1  - Tiersch, Brigitte
A1  - Koetz, Joachim
T1  - Polymer-induced structural changes in lecithin/sodium dodecyl sulfate-based multilamellar vesicles
N2  - Aqueous concentrated lecithin mixtures (asolectin from soybean) show typical lamellar liquid crystalline behavior and the individual lamellae tend to form spherical supramolecular structures, i.e., multilamellar vesicles. When part of the lecithin is replaced by the anionic surfactant sodium dodecyl sulfate (SIDS), the compact multilamellar vesicles disappear and the viscosity decreases. By adding oly(diallyldimethylammonium chloride) (PDADMAC) to the lecithin/SDS system, the formation of multilamellar vesicles can be induced again and the viscosity increases. However, one characteristic feature of these polymer-modified systems is a temperature-dependent phase transition from a compact multilamellar vesicle phase to a more swollen liquid crystalline phase. The polymer-modified multilamellar compact vesicles are of interest for utilization as new thermosensitive drug delivery systems. (C) 2003 Elsevier Inc. All rights reserved
Y1  - 2004
SN  - 0021-9797
ER  - 
TY  - JOUR
A1  - Koetz, Joachim
A1  - Bahnemann, Jennifa
A1  - Kosmella, Sabine
T1  - The influence of a cationic polyelectrolyte on the inverse micellar region of the ternary system sulfobetaine/ water/alcohol
Y1  - 2004
UR  - http://www3.interscience.wiley.com/cgi-bin/fulltext/106577728/PDFSTART
SN  - 0887-624X -
ER  - 
TY  - JOUR
A1  - Koetz, Joachim
A1  - Günther, Claudia
A1  - Kosmella, Sabine
A1  - Kleinpeter, Erich
A1  - Wolf, Gunter
T1  - Polyelectrolyte induced structural changes in the isotropic phase of the system sulfobetaine/pentanol/toluene/ water
Y1  - 2004
ER  - 
TY  - JOUR
A1  - Robertson, Daniela
A1  - Hellweg, Thomas
A1  - Tiersch, Brigitte
A1  - Koetz, Joachim
T1  - Polymer induced structural changes in lecithin/SDS-based multilamellar vesicles
Y1  - 2004
SN  - 0021-9797
ER  -