[24p-F407-1~17] 22.1 Joint Session M "Phonon Engineering"

▼ [24p-F407-1] Enhancement in Thermal Conductivity of CNT/Polymer Composite Ribbons via Optimization of Casting Conditions and Post-treatment

〇(P)Nikita Kumari¹, Ryo Abe¹, Naofumi Okamoto¹, Manish Pandey¹, Masakazu Nakamura¹ (1.NAIST)

Keywords:Carbon nanotube, Orientation, Thermal conductivity

We have recently established a new orientation technique to fabricate scalable films of CNT/polymer composite through a programmable robotic dispenser. Using this technique, ribbon-like films are obtained on the desired substrates by drawing the CNT/polymer composite ink, which is extruded through a narrow needle. Moreover, CNT orientation can also be optimized by tuning the casting parameters, wettability of the ink to the substrate, and ink composition. In this work, CNT/polymer composite films were fabricated using the robotic dispenser and CNT-orientation intensity of films was estimated by the mapping of G-band intensity ratio. For the oriented films, improvement in the corresponding thermal diffusivity and TC was also obtained. Moreover, it was found that the post-treatment, done for peeling the film off the substrate, also affected the TC which can be attributed to variation in the residual organic components in the peeled film. To probe it further, the film fabrication conditions and post-treatment conditions were varied and it was observed that the corresponding TC increased with decreasing cross-sectional area. Through optimized post-treatment of the oriented CNT/polymer composite ribbons, i.e., by varying the dipping time and temperature of the solvent bath, the in-plane TC of more than 200 W/mK was obtained, which is comparable to the state-of-the-art composite films fabricated with various type of oriented fillers. In the literature, increase in TC by increasing the filler loading is typically reported in the literature; however, often, there is a trade-off between film flexibility and the TC. Rather, the key advantages of the present technique, such as i) scalability, ii) cost-efficient processability, iii) orientation, iii) flexible and freestanding film, and iii) high TC, match the desired requirements for the commercialization.