Directed assembly of carbon nanocones into wires with an epoxy coating in thin films by a combination of electric field alignment and subsequent pyrolysis

We report on a nanoparticle manipulation method for assembling carbon nanocones and disks (CNCs) into molecular wires that create a regular two-dimensional network inside thin films. This technique includes electric field induced assembly and electric field orientation (dielectrophoresis), curing and pyrolysis. First, CNCs are dispersed near to the individual particle scale in a two component epoxy adhesive containing phenolic resin. Second, a thin layer (⩽10 μm) of this dispersion is spread onto interdigitated metal electrodes (spacing between 10 and 100 μm) on a glass substrate (area of several cm2). CNC wires are assembled and aligned by an alternating electric field (∼1 kHz, ∼1 kV/cm) yielding an epoxy film with uniaxially aligned CNC pathways (diameter 1–5 μm) in-plane. Third, the aligned film is cured by heating, which leads to a solid film where the wire alignment is maintained within the cross-linked polymer matrix. Finally, most of the cured epoxy is removed from in between the CNC wires by further heating (pyrolysis), which results in a network of aligned, separated wires with a CNC interior and polymer covering. This procedure provides a general concept for forming aligned and stable networks of CNC wires over large surfaces.