Grafting of 4-(2,4,6-Trimethylphenoxy)benzoyl onto Single-Walled Carbon Nanotubes in Poly(phosphoric acid) via Amide Function

Single-walled carbon nanotubes (SWCNTs), which were commercial grade containing 60–70 wt% impurity, were treated in a mild poly(phosphoric acid) (PPA). The purity of PPA treated SWCNTs was greatly improved with or without little damage to SWCNTs framework and stable crystalline carbon particles. An amide model compound, 4-(2,4,6-trimethylphenoxy)benzamide (TMPBA), was reacted with SWCNTs in PPA with additional phosphorous pentoxide as “direct” Friedel–Crafts acylation reaction to afford TMPBA functionalized SWCNTs. All evidences obtained from Fourier-transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, scanning electron microcopy, and transmission electron microscopy strongly supported that the functionalization of SWCNTs with benzamide was indeed feasible

Effect of Substrate Morphology on Growth and Field Emission Properties of Carbon Nanotube Films

Carbon nanotube (CNT) films were grown by microwave plasma-enhanced chemical vapor deposition process on four types of Si substrates: (i) mirror polished, (ii) catalyst patterned, (iii) mechanically polished having pits of varying size and shape, and (iv) electrochemically etched. Iron thin film was used as catalytic material and acetylene and ammonia as the precursors. Morphological and structural characteristics of the films were investigated by scanning and transmission electron microscopes, respectively. CNT films of different morphology such as vertically aligned, randomly oriented flowers, or honey-comb like, depending on the morphology of the Si substrates, were obtained. CNTs had sharp tip and bamboo-like internal structure irrespective of growth morphology of the films. Comparative field emission measurements showed that patterned CNT films and that with randomly oriented morphology had superior emission characteristics with threshold field as low as ~2.0 V/μm. The defective (bamboo-structure) structures of CNTs have been suggested for the enhanced emission performance of randomly oriented nanotube samples