We present a detailed study of the influence of carbon nanotube (CNT) characteristics on the electrical conductivity of polystyrene nanocomposites produced using a latex‐based approach. We processed both industrially‐produced multi‐wall CNT (MWCNT) powders and MWCNTs from vertically‐aligned films made in‐house, and demonstrate that while the raw CNTs are individualized and dispersed comparably within the polymer matrix, the electrical conductivity of the final nanocomposites differs significantly due to the intrinsic characteristics of the CNTs. Owing to their longer length after dispersion, the percolation threshold observed using MWCNTs from vertically‐aligned films is five times lower than the value for industrially‐produced MWCNT powders. Further, owing to the high structural quality of the CNTs from vertically‐aligned films, the resulting composite films exhibit electrical conductivity of 103 S m−1 at 2 wt% CNTs. On the contrary, composites made using the industrially‐produced CNTs exhibit conductivity of only tens of S m−1. To our knowledge, the measured electrical conductivity for CNT/PS composites using CNTs from vertically‐aligned films is by far the highest value yet reported for CNT/PS nanocomposites at this loading.

Fruits of the forest: A desktop reactor rapidly grows forests of aligned carbon nanotubes (CNTs) to heights of many millimeters by atmospheric‐pressure chemical vapor deposition (see picture). This low‐cost apparatus achieves the reaction temperature by resistive heating of a suspended silicon platform, and achieves a 20‐fold increase in CNT growth rate by thermal pretreatment of the reactant mixture. The film thickness is monitored in situ.

Rapid continuous thermal control of chemical reactions such as those for chemical vapor deposition (CVD) growth of nanotubes and nanowires cannot be studied using traditional reactors such as tube furnaces, which have large thermal masses. We present the design, modeling, and verification of a simple, low-cost reactor based on resistive heating of a suspended silicon platform. This system achieves slew rates exceeding 100 degrees C/s, enabling studies of rapid heating and thermal cycling. Moreover, the reaction surface is available for optical monitoring. A first-generation CVD apparatus encapsulates the heated silicon platform inside a sealed quartz tube, and initial experiments demonstrate growth of films of tangled single-wall and aligned multiwall carbon nanotubes using this system. The reactor can be straightforwardly scaled to larger or smaller substrate sizes and may be extended for a wide variety of reactions, for performing in situ reaction diagnostics, for chip-scale growth of nanostructures, and for rapid thermal processing of microelectronic and micromechanical devices.

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