Papers by Keyword: Microstructured

Abstract: In this paper, polyaniline was successfully synthesized by soap-free emulsion polymerization with glycolic acid ethoxylate lauryl ether as dopant and characterized by particle size and distribution measurement, electron microprobe, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The particle size and distribution measurement indicated that the doped polyaniline is monodisperse and micro-structured. Electron microprobe results showed that its morphology is square slice with different square area and almost the same thickness of about 0.5μm. XRD result illustrated that the polymer possess high crystallinity of 31.43%. FT-IR spectrum revealed the chemical structure of the polyaniline doped with glycolic acid ethoxylate lauryl ether. TGA result showed its good thermal stability and purity.

Abstract: Within the project “Functional Surfaces via Micro- and Nanoscaled Structures” an investment casting process to produce 3-dimensional functional surfaces down to a structural size of 1µm on near-net-shape-casting parts will be developed. The common way to realise functional microscale features on metallic surfaces is to use laser ablation, electro discharge machining or micro milling. The handicap of these processes is their limited productivity. In order to raise the efficiency, microscale features will be replicated by use of the investment casting process. The main research objective deals with the investigation of the single process steps with regard to the moulding accuracy. Actual results concerning making of the wax pattern and the ceramic mould as well as the casting of an Aluminium alloy will be presented. By using the example of an intake manifold of a gasoline race car engine a technical shark skin surface was defined in order to reduce the drag of the in-coming air. Possible process stategies to realise microscale features on an inner surface of a casting part were developed.

Abstract: The majority of organismic surfaces, like the plant cuticle, is not smooth but micro-structured. Moreover, they are often covered with hydrophobic wax crystals, some hundred nm in size. The combination of micro- and nanostructures, together with a hydrophobic chemistry, generates the phenomenon of super-hydrophobicity: Water-droplets on such surfaces exhibit contact angles above 140°. Furthermore, dirt particles can barely adhere and are removed by running water only, hence they are called ‘self-cleaning’. The underlying physico-chemical principles were successfully applied to technical prototypes. This technical conversion was patented and the trade mark Lotus-Effect® was introduced in the mid 1990s. Since then several Lotus-Effect® products like a façade paint, a glass coating or a spray were introduced. Another area of application for which prototypes exist, are textiles for awnings, tents or other outdoor purposes. Recently a different aspect of such surfaces is investigated: structures retaining air under water. Several floating plants and semiaquatic animals show this ability. The aim of this project is to develop technical surfaces for long time application in ships and pipelines, as an air film between surface and liquid leads to drag reduction and thus savings of energy.