Synthesis of an organic conductive porous material using starch aerogels as template for chronic invasive electrodes.

We report the development of an organic conducting mesoporous material, as coat for invasive electrodes, by a novel methodology based on the use of starch aerogel as template. The poly(3,4-ethylenedioxythiophene) (PEDOT) aerogel was synthesized by polymerization of 3,4-ethylenedioxythiophene within a saturated starch aerogel with iron (III) p-toluenesulfonate (oxidizing agent) and subsequent removal of the polysaccharide template, followed by supercritical CO2 drying. The chemical structure and oxidation state of the resulting material were studied by Raman spectroscopy. The morphology and surface properties of the obtained nanoporous material were investigated by scanning electron microscopy (SEM), micro computed tomography (µCT) and nitrogen adsorption-desorption techniques. The composition and thermal behaviour were evaluated by energy dispersive spectroscopy (EDS) and thermogravimetric analysis (TGA) respectively. A preliminary biocompatibility test verified the non-cytotoxic effects of the PEDOT aerogel. The large surface area and wide pore size distribution of the PEDOT conductive aerogel, along with its electrical properties, enable it to be used as extracellular matrix scaffold for biomedical applications.

Flame aerosol deposition of Y2O3:Eu nanophosphor screens and their photoluminescent performance.

Screens of Y(2)O(3):Eu(3+)-nanophosphor (d(BET) = 24 nm) with coating densities in the range 0.23-3.8 mg cm(-2) were obtained by flame aerosol deposition (FAD) from nitrate-based precursors. The average deposition rate was 0.22 mg cm(-2) min(-1). Porosity of the obtained deposits was 0.973 +/- 0.004. Light scattering of the coatings in the visible range showed a Rayleigh-like dependence on wavelength and, in comparison to the screens made of the commercial micrometer-sized phosphor powder (d(SEM) = 4 microm), was reduced by up to two orders of magnitude. As a result, the nanophosphor coatings maintained nearly constant brightness in a very wide range of coating densities. Furthermore, it should be expected that a substantially improved screen resolution can be achieved with such screens. For excitation at a wavelength of 254 nm, the maximum brightness of the FAD-deposited (Y(0.92)Eu(0.08))(2)O(3) phosphor screens in the transmission mode was nearly one third of that of the screens made of the commercial phosphor. It was demonstrated that light reflection from the supporting substrate and porosity of the coating significantly influence its photoluminescent performance.

On the influence of nanotube properties, processing conditions and shear forces on the electrical conductivity of carbon nanotube epoxy composites.

We analyse statistical and kinetic percolation thresholds and maximum electrical conductivities of carbon nanotube epoxy composites as a function of shear forces, processing conditions, nanotube type and dimensions. Entangled and non-entangled nanotubes of different lengths (15-100 microm) and thicknesses (12-80 nm) have been obtained with three different synthesis methods based on catalytic or plasma enhanced chemical vapour deposition. The dispersions were processed either solely with a dissolver disk or additionally with a three roll calender. Care was taken to prevent unintentional shearing (e.g. through convection) in all samples that were not subject to deliberate shearing. It was found that shear forces have a similar influence on kinetic percolation thresholds and composite conductivities independent of nanotube types and dimensions.