Room-Temperature Dielectric Switchable Nanocomposites.

Room-temperature switchable dielectric materials are of interest for many applications, including solar energy storage, smart switches, automatic filters, and next-generation sensors. Here, a temperature-triggered dielectric switchable nanocomposite by dispersing octadecylamine-grafted multiwalled carbon nanotubes (ODA-MWCNTs, for short) into hexadecane is reported. The composite has low permittivity at molten state and high permittivity at frozen state, and the permittivity switch is triggered around 18 °C. The highest permittivity contrast ratio reaches 106.4 at 2.0% CNT volume fraction. The composite shows frequency-sensitive and temperature-ramping-rate-sensitive properties. Further investigation indicates that the permittivity switch is caused by the change of the ODA-MWCNT percolating networks during phase transition. [ABSTRACT FROM AUTHOR]