@article{NoteKoetzKosmella2006,
  author    = {Note, Carine and Koetz, Joachim and Kosmella, Sabine},
  title     = {Structural changes in poly(ethyleneimine) modified microemulsion},
  series = {Journal of colloid and interface science},
  volume    = {302},
  journal   = {Journal of colloid and interface science},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0021-9797},
  doi       = {10.1016/j.jcis.2006.06.071},
  pages     = {662 -- 668},
  year      = {2006},
  abstract  = {The influence of branched poly(ethyleneimine) on the phase behavior of the system sodium dodecylsulfate/toluene-pentanol (1:1)/water has been studied. The isotropic microemulsions still exist when water is replaced with aqueous solutions of PEI (up to 30\% in weight), but their stability is significantly influenced. From a polymer concentration of 20 wt\%, the polymer enhances the solubilization of water in oil, changes the sign of the spontaneous curvature of the surfactant film, and induces an inversion of the microemulsion type from water-in-oil (L-2) to oil-in-water (L-1), by the formation of a bicontinuous channel. Further investigations show that the addition of polymer in the L-2 phase changes the droplet-droplet interactions as the conductivity drops and the percolation disappears. In the bicontinuous channel, higher viscosities can be detected, as well as a weak percolation followed by a steep increase of the conductivity, which can be related to evident structural changes in the system. DSC measurements allow then to follow the changes of the water properties in the system, from interfacial-water in the L-2 phase to free-water in the sponge-like phase. Finally, all the measurements performed permit to characterize the structural transitions in the system and to understand the role of the added polymer.},
  language  = {en}
}
@article{NoteKosmellaKoetz2006,
  author    = {Note, Carine and Kosmella, Sabine and Koetz, Joachim},
  title     = {Poly(ethyleneimine) as reducing and stabilizing agent for the formation of gold nanoparticles in w/o microemulsions},
  series = {Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects},
  volume    = {290},
  journal   = {Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects},
  number    = {1-3},
  publisher = {Elsevier},
  address   = {Amsterdam},
  issn      = {0927-7757},
  doi       = {10.1016/j.colsurfa.2006.05.018},
  pages     = {150 -- 156},
  year      = {2006},
  abstract  = {This paper is focused on the use of branched poly(ethyleneimine) (PEI) as reducing as well as stabilizing agent for the formation of gold nanoparticles in different media. The process of nanoparticle formation was investigated, in the absence of any other reducing agents, in microemulsion template phase in comparison to the nucleation process in aqueous polymer solution. On the one hand, it was shown that the polyelectrolyte can be used for the controlled single-step synthesis and stabilization of gold nanoparticles via a nucleation reaction and particles with an average diameter of 7.1 nm can be produced. On the other hand, it was demonstrated that the polymer can also act as reducing and stabilizing agent in much more complex systems, i.e. in water-in-oil (w/o) microemulsion droplets. The reverse microemulsion droplets of the quaternary system sodium dodecylsulfate (SDS)/toluene-pentanol (1:1)/water were successfully used for the synthesis of gold nanoparticles. The polymer, incorporated in the droplets, exhibits reducing properties, adsorbs on the surface of the nanoparticles and prevents their aggregation. Consequently, nanoparticles of 8.6 nm can be redispersed after solvent evaporation without a change of their size. Nevertheless, the polymer acts already as a "template" during the formation of the nanoparticles in water and in microemulsion, so that an additional template effect of the microemulsion is not observed. The particle formation for both methods is checked by means of UV-vis spectroscopy and the particle size and size distribution are investigated via dynamic light scattering and transmission electron microscopy (TEM). (c) 2006 Elsevier B.V. All rights reserved.},
  language  = {en}
}
@phdthesis{Note2006,
  author    = {Note, Carine},
  title     = {Influence of hydrophobically modified polyelectrolytes on nanoparticle synthesis in self-organized systems and in water},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-11670},
  school      = {Universit{\"a}t Potsdam},
  year      = {2006},
  abstract  = {The formation of colloids by the controlled reduction, nucleation, and growth of inorganic precursor salts in different media has been investigated for more than a century. Recently, the preparation of ultrafine particles has received much attention since they can offer highly promising and novel options for a wide range of technical applications (nanotechnology, electrooptical devices, pharmaceutics, etc). The interest derives from the well-known fact that properties of advanced materials are critically dependent on the microstructure of the sample. Control of size, size distribution and morphology of the individual grains or crystallites is of the utmost importance in order to obtain the material characteristics desired. Several methods can be employed for the synthesis of nanoparticles. On the one hand, the reduction can occur in diluted aqueous or alcoholic solutions. On the other hand, the reduction process can be realized in a template phase, e.g. in well-defined microemulsion droplets. However, the stability of the nanoparticles formed mainly depends on their surface charge and it can be influenced with some added protective components. Quite different types of polymers, including polyelectrolytes and amphiphilic block copolymers, can for instance be used as protecting agents. The reduction and stabilization of metal colloids in aqueous solution by adding self-synthesized hydrophobically modified polyelectrolytes were studied in much more details. The polymers used are hydrophobically modified derivatives of poly(sodium acrylate) and of maleamic acid copolymers as well as the commercially available branched poly(ethyleneimine). The first notable result is that the polyelectrolytes used can act alone as both reducing and stabilizing agent for the preparation of gold nanoparticles. The investigation was then focused on the influence of the hydrophobic substitution of the polymer backbone on the reduction and stabilization processes. First of all, the polymers were added at room temperature and the reduction process was investigated over a longer time period (up to 8 days). In comparison, the reduction process was realized faster at higher temperature, i.e. 100°C. In both cases metal nanoparticles of colloidal dimensions can be produced. However, the size and shape of the individual nanoparticles mainly depends on the polymer added and the temperature procedure used. In a second part, the influence of the prior mentioned polyelectrolytes was investigated on the phase behaviour as well as on the properties of the inverse micellar region (L2 phase) of quaternary systems consisting of a surfactant, toluene-pentanol (1:1) and water. The majority of the present work has been made with the anionic surfactant sodium dodecylsulfate (SDS) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) since they can interact with the oppositely charged polyelectrolytes and the microemulsions formed using these surfactants present a large water-in-oil region. Subsequently, the polymer-modified microemulsions were used as new templates for the synthesis of inorganic particles, ranging from metals to complex crystallites, of very small size. The water droplets can indeed act as nanoreactors for the nucleation and growth of the particles, and the added polymer can influence the droplet size, the droplet-droplet interactions, as well as the stability of the surfactant film by the formation of polymer-surfactant complexes. One further advantage of the polymer-modified microemulsions is the possibility to stabilize the primary formed nanoparticles via a polymer adsorption (steric and/or electrostatic stabilization). Thus, the polyelectrolyte-modified nanoparticles formed can be redispersed without flocculation after solvent evaporation.},
  subject      = {Mikroemulsion},
  language  = {en}
}