Electroconductive cotton textile has been prepared by a simple dipping-drying coating technique using safely functionalized multiwalled carbon nanotubes (f-MWCNTs). Owing to the surface functional groups, thef-MWCNTs become strongly attached with the cotton fibers forming network armors on their surfaces. As a result, the textile exhibits enhanced electrical properties with improved thermal conductivity and therefore is demonstrated as a flexible electrothermal heating element. The fabricatedf-MWCNTs/cotton textile can be heated uniformly from room temperature toca. 100°C within few minutes depending on the applied voltage. The textile shows good thermal stability and repeatability during a long-term heating test.

A new and safe method has been developed to functionalize multiwalled carbon nanotubes (MWCNTs) with fewer surface defects, which significantly increases their dispersibility in water. MWCNTs are pretreated in pure ethanol by a supersonic homogenizer. Then, the mixture is dried and soaked in weak citric acid solution. Finally, the MWCNTs in the citric acid solution are treated with radio frequency (13.56 MHz) oxygen plasma. As a result, many carboxyl functional groups are attached onto the MWCNT surfaces and stable dispersion of the MWCNTs in water is obtained. The treatment conditions are optimized in this study.

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Single-walled carbon nanotubes (SWNTs) are synthesized by the arc discharge method in He gas, where three directions of discharge current relative to gravity are selected and their production rates are compared. The soot production rate for the upward discharge current is larger than those for the horizontal and downward discharge currents. Also, the qualities of the produced SWNTs for the three cases are almost the same. The effect of a steady magnetic field (3.0 mT) perpendicular to the discharge current direction (J × B arc discharge) is also examined. This magnetic field increases the soot production rate for all three discharge current directions. The estimated ratio of the number of SWNT bundles to the number of carbon particles is higher for the upward discharge current in the case of B = 0. This ratio increases significantly for the horizontal and downward discharge currents when a magnetic field is applied.