Three-dimensional printing of boron nitride platelets/polylactic acid composites: Achieving enhanced through plane thermal conductivity and decent mechanical properties

Abstract

Thermally conductive polymer composites (TPMCs) hold immense potential, particularly in modern microelectronics thermal management. However, their practical enhancement in thermal performance, in particular the thermal conductivity (TC) in the through plane (κ⊥), often lags behind theoretical predictions attributable to thermal resistance at the interface and the pivotal dependence of anisotropic filler orientation on thermal conductivity. To harness the full capabilities of TPMCs and overcome thermal management challenges, we developed an innovative strategy focused on achieving optimal filler orientation. Employing 3D printing (FDM) technology, we constructed highly vertically oriented hexagonal boron nitride/Polylactic acid composites by layer-by-layer deposition, thereby maximizing the inherent high κ⊥ of hBN. This innovative composite with highly vertically oriented hBN exhibits significantly enhanced κ⊥ up to 3.04 Wm−1 K−1, which is 1348% and 420% enhanced compared to the polylactic acid (PLA) and paralleled counterparts. Scanning electron microscopy and x-ray diffraction show orientation of hBN in PLA matrix, due to the shearing and squeezing effects of FDM when melting and depositing. Additionally, the tensile strength exhibited by polymer composites is commendable, with all values exceeding 22 MPa. Along with extraordinary thermal management performances and mechanical strength, and the customizability using FDM technology, paves the way for TPMCs to revolutionize thermal management applications. Highlights: Constructed the vertically oriented hexagonal boron nitride within the matrix. Dramatically boosted through-plane TC in the composite. FDM enables the customization of diverse and intricate shapes. Implemented a simple strategy for optimizing composite properties. Achieving balance between thermal conductivity and mechanical properties.