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Phase change materials (PCMs) have been widely used in passive thermal management and energy storage due to their high latent heat capacity. However, the low thermal conductivity and leakage problems of PCMs are two bottlenecks for its application in the field of heat-related applications. Although many present studies can tackle one or two of these problems by preparing phase change composites (PCCs), it is still a challenge to achieve high performance PCCs with excellent thermal, mechanical, and phase change properties simultaneously. In this work, we report a spatial confining forced network assembly (SCFNA) method to efficiently prepare the thermal conductive, flexible, leak-proof hexagonal boron nitride/paraffin wax/ polydimethylsiloxane (hBN/PW/PDMS) PCCs by constructing hBN and PW thermal conductive networks as the functional matrix of PCCs. In the hBN/PW/PDMS PCCs, PW is served as the PCM, a dense hBN network provides the high thermal conductivity, and the mechanical properties and shape stability are provided by PDMS. The hBN/PW/PDMS PCCs as thermal interface materials reduce the LED chips surface temperature and exhibit efficient and reliable thermal management performance. Our work provides an efficient and economical method for the preparation of PCCs with outstanding thermal management capability. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) printing is a layered additive manufacturing technology. In common 3D printing methods, direct ink writing (DIW) and fused deposition modeling (FDM) are new extrusion-based technologies. FDM works by melting a hot-melt material and squeezing it out through a tiny nozzle. Conversely, DIW, accurately deposit accurate amount of paste at different distances through the conveying system (extruder). As a unique approach, this technology introduces design freedom, versatility and stability into the printing structure at the same time. In addition, DIW technology is suitable for thermoset 3D printing. The influences of filler orientation in polymer matrix and printing paths on the thermal conductivity (λ) of thermoset 3D printing products are worth studying. Therefore, we built a thermoset 3D printer, and optimized the structure of the nozzle device, effectively improved the printing accuracy. Polydimethylsiloxane (PDMS) and hexagonal boron nitride (h BN) are selected as polymer matrix and thermally conductive filler, respectively. Compared with pure PDMS, the λ value of h BN/PDMS composites increases obviously with increasing h BN content. Meanwhile, the mechanical properties of composites with different printing paths are systematically studied. This designable orientation provides opportunities and challenges for other functional structure design such as hollow structure. [Display omitted] [ABSTRACT FROM AUTHOR]