Scientists from Japan have developed a flexible nanocomposite film with a cellulose nanofiber matrix that can be equipped with thin-film devices for effective dissipation of heat
The development in the electronics industry is by fabricating powerful, thinner, lightweight, and flexible devices, but as these devices become thin, the space for accommodating inner working components is reduced. Traditional heat sinks materials are large and are difficult to be incorporated into thin-film electronics which results in a major issue of heat dissipation that is essential for protecting electronic gadgets. Numerous substrate materials can work as heat diffusers in the form of thin films, but the majority of them diffuse heat in the in-plane direction isotropically. Hence, Dr. Uetani and his team, including Assistant Professor Shota Tsuneyasu from the National Institute of Technology, Oita College, and Prof. Toshifumi Satoh from Tokyo Polytechnic University, both in Japan, have developed a nanocomposite film composed of cellulose nanofibers and carbon fiber-fillers that displayed superior in-plane anisotropic thermal conductivity.
“For a substrate on which multiple devices are mounted in high density, it is necessary to control the direction of thermal diffusion and find an effective heat removal path while thermally insulating between the devices. The development of substrate films with high anisotropy in in-plane thermal conductivity is, therefore, an important target,” says Kojiro Uetani, Junior Associate Professor, Tokyo University of Science
Numerous thermally conductive fillers have been suggested to improve thermal conductivity. Fibrous fillers like carbon fibers (CF), on the other hand, can deliver in-plane anisotropy in two-dimensional (2D) materials due to their structural anisotropy. It is important to choose a matrix with high thermal conductivity. Cellulose nanofibers (CNFs) derived from the mantle of ascidians are claimed to possess higher thermal conductivity (approximately 2.5 W/mK) than traditional polymers, making them ideal for application as a heat-dissipating material. Researchers developed an aqueous suspension of CFs and CNFs and then implemented a method known as liquid 3D patterning. The process resulted in a nanocomposite that had a cellulose matrix with uniaxially aligned carbon fibers. To verify the films’ thermal conductivity, the researchers used a laser-spot periodic heating radiation thermometry technique. In addition to this, the CF/CNF films can also be recycled. This enables scientists to derive the CFs by burning the cellulose matrix so that it could be reused. These outcomes can serve as a framework for engineering 2D films with unique heat dissipating patterns and also could boost sustainability in the process
“The waste that we humans generate has a huge environmental impact. Heat transfer fillers, in particular, are often specialized and expensive materials. As a result, we wanted to create a material that does not go to waste after usage but can be recovered and reused for further applications.” said Kojiro Uetani
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