Production of CaCO3/hyperbranched polyglycidol hybrid films using spray-coating technique.

Biomineralizing organisms employ macromolecules and cellular processing strategies in order to produce highly complex composite materials such as nacre. Bionic approaches translating this knowledge into viable technical production schemes for a large-scale production of biomimetic hybrid materials have met with limited success so far. Investigations presented here thus focus on the production of CaCO(3)/polymer hybrid coatings that can be applied to huge surface areas via reactive spray-coating.

Characterizing dispersion and fragmentation of fractal, pyrogenic silica nanoagglomerates by small-angle X-ray scattering.

Typical characterization of nanoparticle dispersion and compounding processes by dynamic light scattering (DLS) and TEM lack quantitative information on fractal structure, aggregation number, and specific surface area. In this work a synchrotron ultra-small-angle X-ray scattering (USAXS) investigation on diffusion flame and 'Aerosil' silica powders, as well as on their desagglomeration by high-pressure liquid dispersion (200-1400 bar) is presented. Primary particle size, polydispersity, and specific surface area are measured for powders, stirred-in dispersions, and after high-pressure processing with identical results, showing the in-situ applicability of USAXS.

Turbulent hydrodynamic stress induced dispersion and fragmentation of nanoscale agglomerates.

High pressure dispersion nozzles of 2.5-10 mm length and 125 microm diameter have been characterized in terms of fluid dynamics and dispersion experiments at 100-1400 bar. Elongational stresses at the nozzle entry (5 x 10(5) Pa) and turbulent stresses up to 10(5) Pa at a Reynolds number of 25,000 in turbulent channel flow are identified crucial for desagglomeration and aggregate fragmentation.

High-pressure liquid dispersion and fragmentation of flame-made silica agglomerates.

The influence of primary particle diameter and the degree of agglomeration of flame-made silica agglomerate suspensions in aqueous solutions is studied by high-pressure dispersion (up to 1500 bar) through a nozzle with a 125 microm inner diameter. These particles were produced (4-15 g/h) by oxidation of hexamethyldisiloxane (HMDSO) in a coflow diffusion flame reactor. Their average primary particle size (10-50 nm) and degree of agglomeration were controlled by varying the oxygen and precursor flow rates.