Carbon Nanotube/Alkane Composites for Efficient Room-Temperature Electrical Switching in Temperature Sensors and Controllers

The electrical switch response is very desirable for developing temperature sensors and controllers. However, current switchable materials based on oxides and ceramics are limited by high transition temperature, low switch ratio, and expensive manufacturing cost for room-temperature electrical regulation applications. Herein, we investigate the processing optimization of carbon nanotubes (CNTs)/alkane switchable composites and present an effective strategy to boost the switch properties. After optimal chemical oxidation and 1-hexadecanol modification, CNTs can be dispersed into hexadecane with remarkable stability and durability. The switch ratio (sigma(solid)/sigma(liquid)) of electrical conductivity in composites could be regulated to more than 6 orders of magnitude. The electrical switch is highly reversible and repeatable during temperature cycles. Further investigation indicates that the switch ratio is affected by molecular chain length of the alkane matrix. It is found that the chain length influences the crystallization morphology of the alkane matrix, which has a significant impact on electrical behavior of the CNT percolation network.