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A scalable strategy to fabricate thermally conductive but electrically insulating polymer composites was urgently required in various applications including heat exchangers and electronic packages. In this work, multilayered ultrahigh molecular weight polyethylene (UHMWPE)/natural graphite (NG)/boron nitride (BN) composites were prepared by hot compressing the UHMWPE/NG layers and UHMWPE/BN layers alternately. Taking advantage of the internal properties of NG and BN fillers, the UHMWPE/NG layers played a decisive role in enhancing thermal conductivity (TC), while the UHMWPE/BN layers effectively blocked the electrically conductive pathways without affecting the thermal conductive pathways. The in‐plane TC, electrical insulation, and heat spreading ability of multilayered UHMWPE/NG/BN composites increased with the increasing layer numbers. At the total fillers loading of 40 wt%, the in‐plane TC of multilayered UHMWPE/NG/BN composites with nine layers was markedly improved to 6.319 Wm−1 K−1, outperforming UHMWPE/BN (4.735 Wm−1 K−1) and pure UHMWPE (0.305 Wm−1 K−1) by 33.45% and 1971.80%, respectively. Meanwhile, the UHMWPE/NG/BN composites still maintained an excellent electrically insulating property (volume resistance~5.40×1014 Ω cm; breakdown voltage~1.52 kV/mm). Moreover, the multilayered UHMWPE/NG/BN composites also exhibited surpassing heat dissipation capability and mechanical properties. Our results provided an effective method to fabricate highly thermal conductive and electrical insulating composites. [ABSTRACT FROM AUTHOR]

Abstract: Highly anisotropic polyolefin elastomer (POE)/natural graphite (NG) composites with high through‐plane thermal conductivity and excellent mechanical properties, in which NG sheet perfectly aligns along one direction, are prepared by two‐roll milling, hot compression, and mechanical cutting. The through‐plane thermal conductivity coefficient of POE/NG composites is markedly improved to be 13.27 W m−1 K−1 at an NG loading of 49.30 vol%. When the composite is used as a thermal management material, it shows excellent heat dissipating capability in the through‐plane direction, which is very important for thermal management in electronic applications. This effective method is highly probable to be widely used for the facile fabrication of polymer‐based thermal management materials. [ABSTRACT FROM AUTHOR]

Thermoelectric generators (TEGs) are environmentally friendly energy harvesting technologies that hold great promise in the field of self-powered electronics and sensing. However, the current development of thermoelectric (TE) devices has largely lagged behind the development of thermoelectric materials, especially in the preparation of thermoelectric components with customizable shapes and excellent properties, which largely limits their practical applications. These issues can be effectively addressed by using 3D printing technology. Here, we print multiple p-type thermoelectric legs (pins) consecutively with this simple technique, and the printed TEGs have excellent thermal potential (288 μV K -1 at room temperature) and excellent temperature response properties, which exhibited an output voltage of 127.94 mV at a temperature difference (Δ T ) of 40 K. The 3D-printed thermoelectric generator enables the collection of thermal energy. In addition, the device has excellent temperature sensing characteristics, and this temperature signal to electrical signal conversion is very rapid, which enables temperature sensing alarms in a wide temperature domain. Combining these features, an energy harvesting and electrical alarm concept for home-scale applications is proposed, which is expected to provide a diverse research idea for the application of next-generation thermoelectric devices.