Orthogonal Carbon Nanofibers by Template‐Mediated Assembly of Discotic Mesophase Pitch

Abstract

view ( Fig. 5a) ordered periodic arrays composed of gold and nickel cylinders are seen throughout the sample. The period and size of the array of nickel and gold cylinders obtained were 200 nm and 100 nm, respectively. The height of the cylinders was determined to be 2 lm from cross-sectional SEM observation. The shape of the cylinders corresponded precisely to that of the anodic porous alumina used as the host material. The enlarged view in Figure 5b revealed that the shape of the gold cylinders formed at unimprinted sites was circular, whereas the shape of the nickel cylinders at the imprinted sites was strained-triangular. The shapes of the cylinders corresponded to those of the pores of the anodic porous alumina shown in Figure 3c.In conclusion, ordered mosaic nanocomposites composed of gold and nickel cylinders were obtained using a sequence of selective penetration of the barrier layer and subsequent metal deposition. In the present process, a large number of variations of the ordered mosaic composite structures are possible by changing the pattern used for imprinting the aluminum. The first deposition process of the guest material can be applied to control the arrangement and density of the deposits in the composites. For example, selective deposition in anodic porous alumina can be used for doping in two-dimensional photonic crystals. [15,16] Selective deposition is also useful for controlling the density of electron emitters using anodic porous alumina templates, where a controlled interval and density are essential for performing effective field emission. [17,18]

Structure of the carbon nanofilaments formed by liquid phase carbonization in porous anodic alumina template

“…During solidification and carbonization by further heating, the orientation is preserved to form finally well-developed platelet structure carbon nanofilaments. This is essentially similar to the carbon nanofilaments formed from mesophase pitch in porous alumina template [18,20]. generates corrosive hydrogen chloride gas, and it is likely that aluminum oxide is etched by such an aggressive gas.…”

“…Jian et al have used mesophase pitch as a carbon precursor [18], while some of the present authors have utilized poly(vinyl)chloride (PVC) and poly(vinyl)alcohol (PVA) [19], both of which form pitch-like liquefied intermediate during thermal decomposition of the polymers. The template materials play an important role on orientation of graphene layers in carbon nanofilaments.…”

Nanotube Surface Arrays: Weaving, Bending, and Assembling on Patterned Silicon

“…The unique shape of the carbon nanotubes and their bundles with the aspect ratio exceeding 1 :10 4 are exploited for the fabrication of one-dimensional nanostructures such as randomly oriented monolayer films [2], oriented nematic arrays [3], arrays on patterned surface areas [4], precisely positioned individual nanotubes [5], and interelectrode functional networks [6]. The ordered growth of vertically oriented densely packed nanotubes on patterned surfaces has been observed [7,8].…”

Liquid crystal engineering of carbon nanofibers and nanotubes

“…Here our goal is to use nanochannels not only for shape control, but also to direct the molecular structure of the material through polyaromatic/alumina surface interactions. We have previously used the discotic naphthalene polymer, AR mesophase, in combination with nanochannel alumina templates to produce unique carbon nanofibers, whose graphene layers lie perpendicular to the fiber axis 14 . This structure reflects the original (uncarbonized) discotic assembly 14 , which is the only one that achieves the desired edge-on molecular anchoring on the inner alumina surfaces while also avoiding elastic director strain 14 .…”