107 research outputs found

    Directed Self-Assembly: Expectations and Achievements

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    Nanotechnology has been a revolutionary thrust in recent years of development of science and technology for its broad appeal for employing a novel idea for relevant technological applications in particular and for mass-scale production and marketing as common man commodity in general. An interesting aspect of this emergent technology is that it involves scientific research community and relevant industries alike. Top–down and bottom–up approaches are two broad division of production of nanoscale materials in general. However, both the approaches have their own limits as far as large-scale production and cost involved are concerned. Therefore, novel new techniques are desired to be developed to optimize production and cost. Directed self-assembly seems to be a promising technique in this regard; which can work as a bridge between the top–down and bottom–up approaches. This article reviews how directed self-assembly as a technique has grown up and outlines its future prospects

    A tool for studying contact electrification in systems comprising metals and insulating polymers

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    We describe an analytical system for in situ measurement of the charge that develops by contact electrification when a ferromagnetic sphere rolls on the surface of a polymer. Ibis system makes it possible to survey the ability of polymeric surfaces to charge by contact electrification. Because the measurement of charge using this tool does not require physical contact of the charged sphere with the measuring electrode, it also enables the kinetics of charging to be examined. The research has focused on the contact charging of spheres having a core-and-shell geometry (a common core of ferromagnetic steel, and a variable shell of thin films of metals, or metals with surface oxides) rolling on the surface of polymeric slabs; it has generated an internally consistent set of data that include the polarity and magnitude of charging for a homologous series of polymers that differ chemically in the pendant group on a polyethylene backbone

    Magnetic self-assembly of three-dimensional surfaces from planar sheets

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    This report describes the spontaneous folding of flat elastomeric sheets, patterned with magnetic dipoles, into free-standing, 3D objects that are the topological equivalents of spherical shells. The path of the self-assembly is determined by a competition between mechanical and magnetic interactions. The potential of this strategy for the fabrication of 3D electronic devices is demonstrated by generating a simple electrical circuit surrounding a spherical cavity
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