Due to the continuous development of high-density power transmission, architectural complexity, miniaturization, functionalization and new technology applications, heat dissipation has become a bottleneck in the development of high-performance computing and electronic equipment. Therefore, it is of great significance to develop innovative high thermal conductivity materials to solve this problem. Common thermal conductive fillers such as aluminum oxide, boron nitride, aluminum nitride, silicon nitride, diamond, graphite, metal particles, and carbon nanotubes (CNTs) , graphene, etc., have been widely used to prepare polymer composites to achieve desired properties.

Among them, carbon nanotubes have a larger aspect ratio and flexibility than metal nanofillers, and can be better integrated into the polymer matrix to meet thermal management requirements. The thermal conductivity of multi-walled carbon nanotubes (MWCNT) is 2586 ~ 3075 W/(mK). However, in previous studies, the addition of carbon nanotubes to polymer composites had limited effects on enhancing thermal conductivity or heat transfer capabilities. Therefore, developing a method that enables ordered arrangement of carbon nanotubes in the preferred direction of the latent channel for phonon transmission, as well as tuning the required filling position in the composite material, is indispensable to achieve the urgent need of rapid thermal conduction. .

3D printing, also known as additive manufacturing, is a process of joining materials layer by layer to create objects from 3D model data. Among them, direct ink writing (DIW) and fused deposition modeling (FDM) are becoming the most successful and widely used processes for manufacturing polymer nanocomposites. Among them, the FDM method is a simple method that can manufacture geometrically complex three-dimensional structures and programmable macro and micro structures. High-aspect-ratio materials for 3D printing can give printed structures special multifunctionality, including those needed in applications such as electrical and thermal management, energy harvesting, energy storage, and sensing.

The combination of 3D printing and carbon nanotubes can provide endless possibilities for programming hierarchically arranged structures. In order to obtain polymer nanocomposites with high thermal conductivity, what is most needed is to add a large amount of fillers to the polymer matrix and control the orientation and position of the fillers. 3D printing has the ability to distribute fillers in specific locations with desired orientations in the composite, helping to create thermal paths and increase thermal conductivity in preferred directions.

Carbon-Nanotube-Filled Polymer Nanocomposites for Scalable Thermal Management ”为题发表于《ACS Applied Nano Materials》。

Recently, Professor Ni Chaoying from the Department of Materials Science and Engineering at the University of Delaware used 3D printing to verify the impact of this process on the thermal conductivity of polymers. The team used 3D printing methods to prepare MWCNTt-filled polylactic acid (PLA) nanocomposites. During the printing process, MWCNTs spontaneously form aligned structures along the printing direction due to the shear force between the MWCNT/PLA composite filament and the nozzle wall. XRD results confirmed the alignment of MWCNTs. Aligned high filler loading not only significantly improves heat transfer but also helps maintain structural integrity when heated. The in-plane thermal conductivity of the vertically aligned 20 wt % MWCNT/PLA nanocomposite at 35°C is 0.575 W/(mK), which is approximately 2.64 times that of the horizontally aligned structure (~ 0.218 W/(mK)) at the same temperature The value is approximately 5.87 times that of pure PLA (0.098 W/(mK)). Infrared thermography performed on the heat sink verified the superior performance of the nanocomposite compared to the matrix polymer. In this study, we achieved additive manufacturing of MWCNT/PLA with both high filling ratio and significant thermal conductivity improvement. This work presents new ideas for the development of 3D printed carbon filler reinforced polymer composites for thermal management related applications such as heat sinks or thermal radiators. The research results were published in ACS Applied Nano Materials under the title "Thermally Conductive 3D-Printed Carbon-Nanotube-Filled Polymer Nanocomposites for Scalable Thermal Management".