Ultrafast and Highly Localized Microwave Heating in Carbon Nanotube Multilayer Thin Films

Carbon nanotubes have emerged as highly effective materials for microwave absorbing applications due to their high electrical conductivity, large aspect ratio, and high temperature stability against oxidation and corrosion. Ultrathin films are fabricated through layer-by-layer deposition of carbon nanotubes and poly(diallyldimethyl ammonium chloride) from aqueous suspensions under ambient conditions. The number of immersion cycles controls the assembled thickness of these coatings, which provides an effective means of precisely tailoring their electrical properties and thermal response to microwaves. Films of thickness below 200 nm are capable of heating to high temperatures when irradiated with low microwave power, reaching over 130 °C in 30 s, at less than 10 W forward power, and rapidly cooling when the power is removed. In contrast to metal thin films, the multilayer carbon nanotube films are active microwave absorbers over a wide range of thickness, making them interesting for applications such as electromagnetic interference shielding and microwave welding.