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Klaus Tauer

Publications and source records attributed to Klaus Tauer.

4 recordsLinked to original sources
PubMed2007

Ion distribution around electrostatically stabilized polystyrene latex particles studied by ellipsometric light scattering.

The ion distribution around electrostatically stabilized polystyrene latex spheres for different ionic strengths is investigated by ellipsometric light scattering. This method is sensitive to the refractive index profile around colloidal particles, which is affected by the local salt content. At an average salt concentration of c* = 10(-4) mol L(-1), the ion concentration at the particle interface increases discontinuously, and a layer of high salt content with 20-30 nm thickness is built up. The observation cannot be explained within the framework of the Poisson-Boltzmann equation; it rather resembles a prewetting transition. Interactions that could possibly lead to a stabilization of the observed layer of high salt content are discussed.

Journal Article↗
PubMed2006

Ellipsometric light scattering for the characterization of thin layers on dispersed colloidal particles.

The thin interface layer on colloids in a liquid can be characterized by applying nulling ellipsometry to a scattering experiment. Close to 90 degrees scattering angle the ellipsometric quantities tan(Psi) and Delta of particles smaller than the wavelength behave like at the Brewster angle of reflection ellipsometry. The minimum of tan(Psi) and the slope of Delta depend on thickness and refractive index of the layer, while the location of the minimum is sensitive to the refractive index of the particle. As an example, the swelling of a thermosensitive layer on colloidal particles has been determined from measurements at two wavelengths.

Journal Article↗
PubMed2004

Tectonic arrangement of BaCO3 nanocrystals into helices induced by a racemic block copolymer.

Morphosynthesis strategies inspired by biomineralization processes gives access to a wide range of fascinating and useful crystalline mesostructures. Biomimetic synthesis of inorganic materials with complex shapes can now be used to control the nucleation, tensorial growth, and alignment of inorganic crystals in a way previously not practicable. Double hydrophilic block copolymers (DHBCs) consisting of a hydrophilic block strongly interacting with inorganic minerals, and a non-interacting hydrophilic block, were recently introduced for the control of mineralization reactions. DHBCs are 'improved versions' of the previously used polyelectrolytes or amphiphiles and are extraordinarily effective in crystallization control. Here, we report on the formation of helices of achiral BaCO(3) nanocrystals in the presence of a racemic DHBC suggesting that a helical alignment can be induced by racemic polymers through selective adsorption on the (110) face of nanocrystals. This mechanism is the key for a better understanding of the self-assembly of chiral organic-inorganic superstructures that don't follow a direct template route.

Barium Compounds↗